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The hummingbird tongue is a fluid trap, not a capillary tube
... While the tongue moves through the air during protrusion, the elastic energy loaded into the groove walls during the flattening is conserved by a remaining layer of liquid inside the grooves acting as an adhesive [45]. When the tongue touches the nectar, the fringed tip opens up [48] and the supply of fluid allows the release of the elastic energy which expands the grooves and pulls the nectar to fill the entire tongue grooves [45]. The tongue is then retracted, the fringes at the tip capture fluid via a natural origami self-folding trap [48], and the tongue, now sealed at the tip and completely filled with nectar, is quickly brought inside the oral cavity while the bill tips are kept separated. ...
... When the tongue touches the nectar, the fringed tip opens up [48] and the supply of fluid allows the release of the elastic energy which expands the grooves and pulls the nectar to fill the entire tongue grooves [45]. The tongue is then retracted, the fringes at the tip capture fluid via a natural origami self-folding trap [48], and the tongue, now sealed at the tip and completely filled with nectar, is quickly brought inside the oral cavity while the bill tips are kept separated. As soon as the tongue is inside the bill, the bill tips close leaving only a small gap through which the tongue grooves are extruded through, wringing the nectar inside the oral cavity near the bill tip, flattening the tongue, and starting the process again with the next cycle [45], with a frequency of around 15Hz [31]. ...
... Zusi [16] therefore concluded that most species of hummingbirds were proximally rhynchokinetic, and a few actually prokinetic, meaning that any dorsally directed bending of the upper jaw would be restricted to the base of the bill. However, Zusi [17] later acknowledged the slight bending of the tip of the upper jaw of hummingbirds observed in videos by Rico-Guevara and Rubega [48] and concluded that distal rhynchokinesis was not only possible but could even facilitate nectar consumption [17]. Furthermore, Zusi [17] underscored the need for "precise measurements of cranial kinesis of live hummingbirds and knowledge of the physical properties of the structural components of the prepalatal upper jaw." ...
Observations of maxillary (upper bill) bending in hummingbirds have been considered an optical illusion, yet a recent description of out-of-phase opening and closing between their bill base and tip suggests a genuine capacity for bill bending. We investigate bill kinematics during nectar feeding in six species of hummingbirds. We employed geometric morphometrics to identify bending zones and combined these data with measurements of bill flexural rigidity from microCT scans to better understand the flexing mechanism. We found that the mandible remains in place throughout the licking cycle, while the maxilla undergoes significant shape deformation, such that the distal portion of the upper bill bends upwards. We propose that bill bending is a key component of the drinking mechanism in hummingbirds, allowing the coordination of bill function (distal wringing and basal expansion) and tongue function (raking/squeegeeing) during intraoral transport. We present a fluid analysis that reveals a combination of pressure-driven (Poiseuille) and boundary-driven (Couette) flows, which have previously been thought to represent alternative drinking mechanisms. Bill bending allows for separation of the bill tips while maintaining a tightly closed middle section of the bill, enabling nectar exploitation in long and narrow flowers that can exclude less efficient pollinators.
... extracting liquid derive from the material properties and structural configuration of the tongue tip and grooves (Rico-Guevara and Rubega 2011;Vogel 2011;Rico-Guevara 2017). Other aspects of the feeding process await further explanation (see Rico-Guevara and Rubega 2017), and patterns of mechanistic variation across hummingbird species (with consequent ecological implications) remain to be described. ...
... Because capillarity models do not explain observed features of nectar intake in hummingbird tongues (Rico-Guevara and Rubega 2011;, the associated equations that have been used for decades (e.g., Heyneman 1983;Kingsolver and Daniel 1983;Kim et al. 2011Kim et al. , 2012 to calculate rates of energy intake while consuming nectar (as well as estimates of optimal floral nectar concentration in hummingbird-pollinated plants; Nicolson and Fleming 2003) are neither accurate nor appropriate. Given that energy content of nectar increases with sugar concentration, but that flow rate concurrently decreases due to elevated dynamic viscosity, "capillary feeders" would optimize rates of energy intake at intermediate nectar concentrations (Baker 1975;Heyneman 1983;Kingsolver and Daniel 1983;Nicolson and Thornburg 2007;Kim et al. 2011Kim et al. , 2012. ...
... Furthermore, the tongue when functioning as an elastic micropump fills an order of magnitude faster than would be expected under capillarity (Rico-Guevara and Rubega 2012; , and thus allows for higher energy intake via elevated licking rates and complete tongue filling. The absence of a strong gravitational effect for the tongue-filling mechanism is also better explained by the fluid trapping and elastic pumping models (see Rico-Guevara and Rubega 2011;. Furthermore, fluid collection by the tongue is only the first step in a chain of intricate processes that have to work in concert to achieve actual nectar feeding (Rico-Guevara 2014). ...
As functional morphologists, we aim to connect structures, mechanisms, and emergent higher-scale phenomena (e.g., behavior), with the ulterior motive of addressing evolutionary patterns. The fit between flowers and hummingbird bills has long been used as an example of impressive co-evolution, and hence hummingbirds’ foraging behavior and ecological associations have been the subject of intense study. To date, models of hummingbird foraging have been based on the almost two-centuries-old assumption that capillary rise loads nectar into hummingbird tongue grooves. Furthermore, the role of the bill in the drinking process has been overlooked, instead considering it as the mere vehicle with which to traverse the corolla and access the nectar chamber. As a scientific community, we have been making incorrect assumptions about the basic aspects of how hummingbirds extract nectar from flowers. In this article, we summarize recent advances on drinking biomechanics, morphological and ecological patterns, and selective forces involved in the shaping of the hummingbird feeding apparatus, and also address its modifications in a previously unexpected context, namely conspecific and heterospecific fighting. We explore questions such as: how do the mechanics of feeding define the limits and adaptive consequences of foraging behaviors? Which are the selective forces that drive bill and tongue shape, and associated sexually dimorphic traits? And finally, what are the proximate and ultimate causes of their foraging strategies, including exploitative and interference competition? Increasing our knowledge of morphology, mechanics, and diversity of hummingbird feeding structures will have implications for understanding the ecology and evolution of these remarkable animals.
... For instance, when the ISW is a direct modification of the feeding apparatus, it will be advantageous for mating but may be disadvantageous for feeding [e.g. spiders (Pollard, 1994); salmon (Darwin, 1859;Witten & Hall, 2002); hummingbirds (Rico-Guevara & Rubega, 2011]. In nectar-feeding birds, ISWs come as modifications of the bill tips to stab and pluck feathers (e.g. ...
... In nectar-feeding birds, ISWs come as modifications of the bill tips to stab and pluck feathers (e.g. Rico-Guevara & Araya-Salas, 2015;Rico-Guevara & Rubega, 2017; A. Rico-Guevara, personal observations), however, bill tip shape is finely tuned to interact with the tongue in order to optimize nectar extraction efficiency (Rico-Guevara & Rubega, 2011;Rico-Guevara, Fan & Rubega, 2015;Rico-Guevara, 2017). Hence, even ISWs that are not exaggerated structures (such as in spiders and salmon) can have an impact on the naturally selected function of the modified trait. ...
... In nectar-feeding birds, ISWs come as modifications of the bill tips to stab and pluck feathers (e.g. Rico-Guevara & Araya-Salas, 2015;Rico-Guevara & Rubega, 2017; A. Rico-Guevara, personal observations), however, bill tip shape is finely tuned to interact with the tongue in order to optimize nectar extraction efficiency (Rico-Guevara & Rubega, 2011;Rico-Guevara, Fan & Rubega, 2015;Rico-Guevara, 2017). Hence, even ISWs that are not exaggerated structures (such as in spiders and salmon) can have an impact on the naturally selected function of the modified trait. ...
We propose a practical concept that distinguishes the particular kind of weaponry that has evolved to be used in combat between individuals of the same species and sex, which we term intrasexually selected weapons (ISWs). We present a treatise of ISWs in nature, aiming to understand their distinction and evolution from other secondary sex traits, including from ‘sexually selected weapons’, and from sexually dimorphic and monomorphic weaponry. We focus on the subset of secondary sex traits that are the result of same‐sex combat, defined here as ISWs, provide not previously reported evolutionary patterns, and offer hypotheses to answer questions such as: why have only some species evolved weapons to fight for the opposite sex or breeding resources? We examined traits that seem to have evolved as ISWs in the entire animal phylogeny, restricting the classification of ISW to traits that are only present or enlarged in adults of one of the sexes, and are used as weapons during intrasexual fights. Because of the absence of behavioural data and, in many cases, lack of sexually discriminated series from juveniles to adults, we exclude the fossil record from this review. We merge morphological, ontogenetic, and behavioural information, and for the first time thoroughly review the tree of life to identify separate evolution of ISWs. We found that ISWs are only found in bilateral animals, appearing independently in nematodes, various groups of arthropods, and vertebrates. Our review sets a reference point to explore other taxa that we identify with potential ISWs for which behavioural or morphological studies are warranted. We establish that most ISWs come in pairs, are located in or near the head, are endo‐ or exoskeletal modifications, are overdeveloped structures compared with those found in females, are modified feeding structures and/or locomotor appendages, are most common in terrestrial taxa, are frequently used to guard females, territories, or both, and are also used in signalling displays to deter rivals and/or attract females. We also found that most taxa lack ISWs, that females of only a few species possess better‐developed weapons than males, that the cases of independent evolution of ISWs are not evenly distributed across the phylogeny, and that animals possessing the most developed ISWs have non‐hunting habits (e.g. herbivores) or are faunivores that prey on very small prey relative to their body size (e.g. insectivores). Bringing together perspectives from studies on a variety of taxa, we conceptualize that there are five ways in which a sexually dimorphic trait, apart from the primary sex traits, can be fixed: sexual selection, fecundity selection, parental role division, differential niche occupation between the sexes, and interference competition. We discuss these trends and the factors involved in the evolution of intrasexually selected weaponry in nature.
... We focused our filming along the distal region of the hummingbird bills, until we found the precise point at which the tomia (cutting edges of the beak) and the tongue interact during the extrusion process. In addition, to test if the tongue was being extruded, and to obtain an estimate of the tongue compression, we measured the tongue thickness and bill aperture employing flat-sided, transparent feeders (e.g., Rico-Guevara and Rubega, 2011). In this case we used a macro lens (Nikon 105 mm f/2.8 VR) coupled to the same highspeed camera noted above, which allowed a larger field of view that encompassed both bill tips and tongue tips . ...
... In this case we used a macro lens (Nikon 105 mm f/2.8 VR) coupled to the same highspeed camera noted above, which allowed a larger field of view that encompassed both bill tips and tongue tips . We opportunistically filmed free-living hummingbirds at private field sites, with existing feeders, in seven countries throughout the Americas (see Rico-Guevara and Rubega, 2011;. We measured 105 foraging bouts of 35 focal birds belonging to 20 species from seven out of the nine hummingbird clades (see Table S1 in the supplementary online Appendix). ...
... In order to understand to which degree optimal foraging (MacArthur and Pianka, 1966;Emlen, 1966) determines hummingbird decisions (Pyke, 1978(Pyke, , 1981(Pyke, , 2016 and observed ecological patterns (bird-plant associations; Maglianesi et al. 2014;Pyke, 2016) we need to develop new nectar intake models (replacing the capillarity model; Rico-Guevara, 2014;. These models need to include both the recent findings on tongue loading (Rico-Guevara and Rubega, 2011;, the nectar off-loading process influenced by the wringer presented in the present paper, and the intraoral transport component. The hidden structures described here are important clues to advance our understanding of hummingbird feeding mechanisms. ...
Nectarivores are animals that have evolved adaptations to efficiently exploit floral nectar as the main source of energy in their diet. It is well known that hummingbirds can extract nectar with impressive speed from flowers. However, despite decades of study on nectar intake rates, the mechanism by which feeding is ultimately achieved − the release of nectar from the tongue so that it can pass into the throat and be ingested − has not been elucidated. By using microCT scanning and macro high-speed videography we scrutinized the morphology and function of hummingbird bill tips, looking for answers about the nectar offloading process. We found near the bill tip, in an area of strong lateral compression of internal mandibular width, that the tomia (cutting edges of the bill) are thinner, partially inrolled, and hold forward-directed serrations. Aligned with these structures, a prominent pronglike structure projects upward and forward from the internal mandibular keel. Distal to this mandibular prong, another smaller maxillary prong protrudes downwards from the keel of the palate. Four shallow basins occur at the base of the mandibular prong on the mandibular floor. Of these, two are small basins located proximally and at the sides of the mandibular prong. A third, slightly larger basin is positioned distally to the first two and directly under the maxillary prong. And the fourth basin, the largest, is found more proximally where the bill becomes thicker, as seen from the side. We documented that this group of structures is integrated into the area of the bill where tongue extrusion occurs, and we hypothesize that they function to enhance the nectar release at each lick. We suggest that this “wringer”, operated by bill and tongue movements, helps to move nectar towards the throat.
... 2.5.2). In some birds (e.g., passerine birds, hummingbirds, toucans, woodpeckers), the lingual nail is elongated beyond the fleshy lingual tip and forms a narrow, stiff brush (e.g., Bock 1972Bock , 1985aRico-Guevara and Rubega 2011;Rico-Guevara 2014;Rico-Guevara et al. 2015). The lingual tip of seed-eating passerine birds is reinforced and thickened by the underlying neomorphic bone, fat bodies, and hydraulic tissues and can be changed from flat to spoon-shaped ( Bock and Morony 1978;Ziswiler 1979). ...
... A pair of hyoid horns articulate with the lateral sides of basihyal-urohyal and are invested in connective tissue sheaths, the hyoid sheaths, which are attached to the fasciae of the jaw muscles or throat ( Figs. 2.5 and 2.6). This hyoid suspension construction enables some birds to protract their tongues far beyond the tip of the beak, as in lorikeets ( Homberger 1980), woodpeckers ( Leiber 1907;Bock 1999a), and hummingbirds (Rico Guevara and Rubega 2011;Rico-Guevara 2014;Rico-Guevara et al. 2015). The hyoid skeleton is suspended between the mandibular rami by fasciae and extrinsic muscles. ...
... Liquid foods (e.g., nectar) and food items that are suspended in water require specialized feeding mechanisms, such as nectar feeding by hummingbirds ( Ewald and Williams 1982;Rico-Guevara and Rubega 2011;Rico-Guevara 2014;Rico-Guevara et al. 2015), lorikeets ( Homberger 1980), and a sandpiper ( Burle et al. 2013); filter feeding by ducks ( Zweers et al. 1977Zweers et al. , 1994van der Leeuw et al. 2003;Skieresz-Szewczyk and Jackowiak 2016) and flamingos ( Zweers et al. 1995); or suspension feeding in phalaropes ( Rubega and Obst 1993). Except for the detailed motion analysis of the beak, tongue, and hyoid in the beak after it was shaken off and re-caught with the beak. ...
The lingual and laryngeal apparatus are the mobile and active organs within the oral cavity, which serves as a gateway to the respiratory and alimentary systems in terrestrial vertebrates. Both organs play multiple roles in alimentation and vocalization besides respiration, but their structures and functions differ fundamentally in birds and mammals, just as the skull and jaws differ fundamentally in these two vertebrate classes. Furthermore, the movements of the lingual and laryngeal apparatus are interdependent with each other and with the movements of the jaw apparatus in complex and little-understood ways. Therefore, rather than updating the existing numerous reviews of the diversity in lingual morphology of birds, this chapter will concentrate on the functional-morphological interdependences and interactions of the lingual and laryngeal apparatus with each other and with the skull and jaw apparatus. It will:1.
Briefly review the salient features of the mammalian head as a baseline against which to understand the uniqueness of the avian head
2.
Describe general morphological features of the lingual and laryngeal apparatus within the context of the skull and jaw apparatus
3.
Contrast some fundamental functional-morphological differences that exist among the jaw, lingual and laryngeal apparatus of birds
4.
Provide models of the movements of the various parts of the lingual and laryngeal apparatus based on biomechanical analyses
5.
Integrate these models with behaviors in thermoregulation, feeding, drinking, and vocalization
6.
Briefly demonstrate how detailed morphological and functional analyses can be tested and expanded by using 3D visualization and animation
7.
Place the provided data in an evolutionary framework
... For instance, handling time increases when the nectar is located deep inside the corolla, while more easily accessible shallower flowers usually have smaller rewards (10,11). Thus, assessments of the importance of feeding mechanisms should consider both ingestion efficiency and reward accessibility, especially in the context of explicit fluid-mouthparts interactions within the nectar reservoir (11)(12)(13)(14)(15)(16). These interactions are crucial for our understanding of the links between physical principles and the adaptations of both plants and pollinators that shape ecological communities. ...
... The microscopic high-speed videos unravel four stages for the lapping process: 1) tongue protrusion, 2) hairs unfolding to load nectar, 3) tongue retraction into the proboscis tube, and 4) offloading the nectar and swallowing. We define T i (i = 14) as the time elapsed in each phase (Fig. 3 A and B and Movie S6). Notably, during the loading process, the hairs unfolded asynchronously along the tongue. ...
The feeding mechanisms of animals constrain the spectrum of resources that they can exploit profitably. For floral nectar eaters, both corolla depth and nectar properties have marked influence on foraging choices. We report the multiple strategies used by honey bees to efficiently extract nectar at the range of sugar concentrations and corolla depths they face in nature. Honey bees can collect nectar by dipping their hairy tongues or capillary loading when lapping it, or they can attach the tongue to the wall of long corollas and directly suck the nectar along the tongue sides. The honey bee feeding apparatus is unveiled as a multifunctional tool that can switch between lapping and sucking nectar according to the instantaneous ingesting efficiency, which is determined by the interplay of nectar-mouth distance and sugar concentration. These versatile feeding mechanisms allow honey bees to extract nectar efficiently from a wider range of floral resources than previously appreciated and endow them with remarkable adaptability to diverse foraging environments.
... Biological kingdom offers the strategies of liquid dynamics that adapt to the natural environment 1-8 , e.g., fog water collection controlled on biological surfaces such as spider silk 1 , beetle back 2 , plant leaf 3 , etc. in mist. They help researchers to understand the liquid behaviors 1,4,[8][9][10][11][12][13][14][15][16][17][18] , and offers theories to design materials used for droplet transport including surfaces with asymmetric structure 1,3,4,7 , gradient wettability 5 and additive energy to the systems 9,10 , etc. Up to now, varieties of materials and theories have been investigated to solve the problems in water acquiring task 9,19-25 . Cactuses are famous for their abilities to live in the desert where drought is normal and water evaporates so quickly. ...
... Scientific RepoRts | 5:17757 | DOI: 10.1038/srep17757 fan out with the maximum radius (R c ) of ~20 μ m (Fig. 1e) at the opens of scales and the minimum radius (r c ) of ~8 μ m at the ends of scales (Fig. 1f). ...
We report that the fast droplet transport without additional energy expenditure can be achieved on the spine of cactus (Gymnocalycium baldianum) with the assistance of its special surface structure: the cactus spine exhibits a cone-like structure covered with tilted scales. A single scale and the spine surface under it cooperatively construct a splayed capillary tube. The arrays of capillary tube formed by the overlapping scales build up the out layer of the spine. The serial drops would be driven by the asymmetric structure resulted from tilt-up scales-by-scales on the cone-shaped spine, and move directionally toward the bottom from top of spine, by means of the Laplace pressure in differences. In addition, after the past of the first droplet, thin liquid film of drop is trapped in the splayed capillary micro-tube on the surface of spine, which greatly reduces the friction of subsequential droplet transport in efficiency. This finding provides a new biological model which could be used to transport droplet spontaneously and directionally. Also this work offers a way to reduce the surface adhesion by constructing liquid film on the surface, which has great significance in prompting droplet transport efficiency.
... The outline of the tongue is basically triangular, and the tongue fits perfectly on the lower beak, in galliform and passerine birds (Iwasaki and Kobayashi, 1986;Homberger and Meyers, 1989;Dehkordi et al., 2010;Jackowiak et al., 2010;Parchami et al., 2010a;Erdogan and Alan, 2012;Erdogan et al., 2012a,b). The tongue is elongated and oval, with many projections, in lamellirostrate birds (King and McLelland, 1984;Iwasaki et al., 1997;Hassan et al., 2010;Jackowiak et al., 2011); lance-shaped in near-passerine birds, such as woodpeckers and sapsuckers (Goodge, 1972;Bock, 1999;Emura et al., 2009a); tassled, fringe-shaped or brush-like in nectarivorous birds (Rand, 1961(Rand, , 1967Paton and Collins, 1989;Wiens, 1992;Downs, 2004;Rico-Guevara and Rubega, 2011); elongated and bulky in birds of prey (Jackowiak and Godynicki, 2005;Emura et al., 2008a,b;Erdogan et al., 2012a); mushroom-like in cormorants (Jackowiak et al., 2006); rasp-like, with enormous projections or a barbed appearance, in penguins (Samar et al., 1995;Kobayashi et al., 1998); and relatively small with no functional projections, in ratite birds (Jackowiak and Ludwig, 2008;Soley, 2009a,b, 2010;Guimarães et al., 2009;Santos et al., 2011;Tivane et al., 2011) (Fig. 1). ...
... The tongue has a brush-like appearance with a groove along its entire length (Downs, 2004). By contrast, hummingbirds, the most highly specialized nectar-feeding/sucking vertebrates, have evolved a specialized tongue that serves as a highly efficient liquid-extraction system (Fleming and Muchhala, 2008;Rico-Guevara and Rubega, 2011) (Table 1). It was assumed that the hummingbird tongue is loaded with nectar via capillary action only, but recent work (Rico-Guevara and Rubega, 2011) has demonstrated that the tip of the hummingbird tongue trap nectar dynamically by rapidly changing its shape during feeding. ...
... flight and specialized tongue and bill movements [9][10][11][12][13] . In contrast, songbirds like finches use a flapbounding flight style and employ their bill primarily for foraging and manipulation (Fig. 1B). ...
Somatosensation allows animals to perceive the external world through touch, providing critical information about physical contact, temperature, pain, and body position. Somatosensory pathways, particularly those related to the rodent vibrissae, have been well-studied in mammals, illuminating principles of cortical organization and sensory processing 1,2. However, comparative studies across diverse vertebrate species are imperative to understand how somatosensory systems are shaped by evolutionary pressures and specialized ecological needs.
Birds provide an excellent model for studying the evolution of somatosensation, as they exhibit remarkable diversity in body plans, sensory capabilities, and behavior. Prior work in pigeons3-6, parrots7, and finches8 have identified general tactile-responsive regions within the avian telencephalon. Yet how somatosensory maps and response properties vary across key avian groups remains unclear. Here, we aimed to elucidate somatotopic organization and neural coding in the telencephalon of Anna's hummingbirds (Calypte anna) and zebra finches (Taeniopygia guttata).
Using in vivo extracellular electrophysiological techniques, we recorded single and multi-unit activity in telencephalic regions of anesthetized hummingbirds and finches. We stimulated the beak, face, trunk, wings, and hindlimbs with controlled tactile stimuli and mapped somatosensory receptive fields. We found distinct representations of body regions distributed across multiple somatosensory zones, with surprising differences in relative areas devoted to key body surfaces, potentially as related to behavioral significance.
... For permissions, please e-mail: journals.permissions@oup.com 2 A. E. Hewes et al. which are the dominant forces during capillarity, are the ones expected to be the main drivers of the tongue filling mechanism. Extensive high-speed videography work with hummingbirds has demonstrated that their tongue does not act as a capillary tube during typical feeding conditions, but instead it uses dynamic filling mechanisms (Rico-Guevara and Rubega 2011;Rico-Guevara et al. 2015). Using high-speed videography at up to 2400 frames per second, it has been demonstrated that the tongue tip acts as a dynamic fluid trap (Rico-Guevara and Rubega 2011). ...
Synopsis
We investigated the kinematics and biomechanics of nectar feeding in five species of honeyeater (Phylidonyris novaehollandiae, Acanthagenys rufogularis, Ptilotula penicillata, Certhionyx variegatus, Manorina flavigula). There is abundant information on honeyeater foraging behaviors and ecological relationships with plants, but there has never been an examination of their nectar-feeding from kinematic and biomechanical perspectives. We analyzed high-speed video of feeding in captive individuals to describe the kinematics of their nectar feeding, with specific focus on describing tongue movements and bill-tongue coordination, and to characterize the mechanism of nectar uptake in the tongue. We found clear interspecific variation in kinematics and tongue filling mechanics. Species varied in lick frequency, tongue velocity, and protrusion and retraction duration, which, in some cases, are relevant for differences in tongue filling mechanisms. We found support for the use of capillary filling in Certhionyx variegatus only. By contrast, Phylidonyris novaehollandiae, Acanthagenys rufogularis, Ptilotula penicillata, and Manorina flavigula employed a modified version of the expansive filling mechanism seen in hummingbirds, as there was dorsoventral expansion of the tongue body, even the portions that remain outside the nectar, once the tongue tip entered the nectar. All species use fluid trapping in the distal fimbriated portion of the tongue, which supports previous hypotheses describing the honeyeater tongue as a “paintbrush.”
... Certainly, some key features are universal in the family and known in no other birds, including their remarkable adaptations for prolonged hovering (Altshuler and Dudley 2002) and nectar extraction (Rico-Guevara et al. 2019;Rico-Guevara and Rubega 2011). In contrast, differences among species in bill length and shape have long been rightly viewed as adaptive, co-evolved responses to-or causes of-the morphology of the flowers they visit for nectar (Maglianesi et al. 2015;Stiles 1981;Temeles and Kress 2003;Weinstein and Graham 2017). ...
Differences among hummingbird species in bill length and shape have rightly been viewed as adaptive in relation to the morphology of the flowers they visit for nectar. In this study we examine functional variation in a behaviorally related but neglected feature: hummingbird feet. We gathered records of hummingbirds clinging by their feet to feed legitimately as pollinators or illegitimately as nectar robbers-"unorthodox" feeding behaviors. We measured key features of bills and feet for 220 species of hummingbirds and compared the 66 known "clinger" species (covering virtually the entire scope of hummingbird body size) with the 144 presumed "non-clinger" species. Once the effects of phylogenetic signal, body size, and elevation above sea level are accounted for statistically, hummingbirds display a surprising but functionally interpretable negative correlation. Clingers with short bills and long hallux (hind-toe) claws have evolved-independently-more than 20 times and in every major clade. Their biomechanically enhanced feet allow them to save energy by clinging to feed legitimately on short-corolla flowers and by stealing nectar from long-corolla flowers. In contrast, long-billed species have shorter hallux claws, as plant species with long-corolla flowers enforce hovering to feed, simply by the way they present their flowers.
... The driving force is not composed of just the capillary force; it is assisted by the pumping force resulting from the change in water evaporation pressure. Figure 11(d) illustrates the water drinking process through the beak of the hummingbird [202][203][204]. Water transport via hummingbird beak is based on a combination of beak macrostructure (Figure 8(b)) and microscale flexible lamella structure. ...
The transport of liquid droplets plays an essential role in various applications. Modulating the wettability of the material surface is crucial in transporting droplets without external energy, adhesion loss, or intense controllability requirements. Although several studies have investigated droplet manipulation, its design principles have not been categorized considering the mechanical perspective. This review categorizes liquid droplet transport strategies based on wettability modulation into those involving (i) application of driving force to a droplet on non-sticking surfaces, (ii) formation of gradient surface chemistry/structure, and (iii) formation of anisotropic surface chemistry/structure. Accordingly, reported biological and artificial examples, cutting-edge applications, and future perspectives are summarized.
... (B) Plant-hummingbird visitation network from the Munchique Natural National Park in western Colombia, reproduced from Ramírez-Burbano et al. paradox' has invited numerous explanatory hypotheses, and no one hypothesis has emerged as a leading explanation (reviewed by Nicolson, 2007b). That said, an accumulation of evidence over the past decade has revealed that hummingbird tongues do not rely on capillary action for nectar uptake (Rico-Guevara & Rubega, 2011;Rico-Guevara, Fan & Rubega, 2015;Rico-Guevara et al., 2019), weakening the argument that the viscosity of highly concentrated nectars limits hummingbird feeding efficiency (Baker, 1975). ...
The ecological co-dependency between plants and hummingbirds is a classic example of a mutualistic interaction: hummingbirds rely on floral nectar to fuel their rapid metabolisms, and more than 7000 plant species rely on hummingbirds for pollination. However, threats to hummingbirds are mounting, with 10% of 366 species considered globally threatened and 60% in decline. Despite the important ecological implications of these population declines, no recent review has examined plant–hummingbird interactions in the wider context of their evolution, ecology, and conservation. To provide this overview, we (i) assess the extent to which plants and hummingbirds have coevolved over millions of years, (ii) examine the mechanisms underlying plant–hummingbird interaction frequencies and hummingbird specialization, (iii) explore the factors driving the decline of hummingbird populations, and (iv) map out directions for future research and conservation. We find that, despite close associations between plants and hummingbirds, acquiring evidence for coevolution (versus one-sided adaptation) is difficult because data on fitness outcomes for both partners are required. Thus, linking plant–hummingbird interactions to plant reproduction is not only a major avenue for future coevolutionary work, but also for studies of interaction networks, which rarely incorporate pollinator effectiveness. Nevertheless, over the past decade, a growing body of literature on plant–hummingbird networks suggests that hummingbirds form relationships with plants primarily based on overlapping phenologies and trait-matching between bill length and flower length. On the other hand, species-level specialization appears to depend primarily on local community context, such as hummingbird abundance and nectar availability. Finally, although hummingbirds are commonly viewed as resilient opportunists that thrive in brushy habitats, we find that range size and forest dependency are key predictors of hummingbird extinction risk. A critical direction for future research is to examine how potential stressors – such as habitat loss and fragmentation, climate change, and introduction of non-native plants – may interact to affect hummingbirds and the plants they pollinate.
... High speed videography has repeatedly overturned assumptions of lingual control in bats, hummingbirds, chameleons and cats (26)(27)(28)(29). By combining kilohertz frame-rate imaging and deep learning based machine vision methods, we tracked the rodent tongue in 3D for the first time and discovered that licks cannot be explained by open loop central pattern generators that drive simple binary ballistic events. ...
Precise control of the tongue is necessary for drinking, eating, and vocalizing. Yet because tongue movements are fast and difficult to resolve, neural control of lingual kinematics remains poorly understood. We combine kilohertz frame-rate imaging and a deep-learning based artificial neural network to resolve 3D tongue kinematics in mice performing a cued lick task. Cue-evoked licks exhibit previously unobserved fine-scale movements which, like a hand searching for an unseen object, were produced after misses and were directionally biased towards remembered locations. Photoinhibition of anterolateral motor cortex (ALM) abolished these fine-scale adjustments, resulting in well-aimed but hypometric licks that missed the spout. Our results show that cortical activity is required for online corrections during licking and reveal novel, limb-like dynamics of the mouse tongue as it reaches for, and misses, targets.
... Paton and Collins 1989). Because feeding from floral corollae requires specific actions of lapping and pumping of sugar-rich viscous solutions, bill and tongue morphology are strongly influenced by the biomechanics of nectar extraction (Rico-Guevara and Rubega 2011;Rico-Guevara et al. 2015). Bill length and curvature are potentially variable according to specialization on particular flowers or plant groups, but dedicated nectar-feeders are easily recognized worldwide. ...
We start with a general description of the structure of the feeding apparatus in birds (Sect. 17.1), then we describe the biomechanics of those parts (Sect. 17.2), including a review of contemporary approaches to the study of bird feeding morphology and function. We establish explicit links between form and function, and consequent relations to foraging behaviors. In Sect. 17.3, we systematically explore the vast diversity of bird feeding environments by grouping foraging (searching) and feeding (handling—consumption) mechanisms that birds use on land, air, and water. Each one of these subsections addresses not only what birds eat, but also how they feed. We dedicate a separate Sect. (17.4) to drinking because most birds have to perform this process regardless of their diet, and often using different mechanisms than the ones they use to feed. We then discuss evolutionary forces and patterns in bird feeding (convergences, radiations, trade-offs, etc.), including functions different from handling and ingestion that also act to shape the feeding apparatus in birds (Sect. 17.5).
... This cycle is repeated about 15 times a second. Modified from Rico Rubega 2011 and permission from Proceedings of the Royal Society B. ...
... Maximizing net meal energy is a general demand of many animals, but how it is achieved may vary depending on the usage of different foraging techniques (Hainsworth et al. 1991;Paul and Roces 2003). Tongues of a variety of animals, which have dynamic surfaces, could reconfigure their surface profiles to improve the nectaruptake volume (Harper et al. 2013;Howell and Hodgkin 1976;Kim et al. 2012;Rico-Guevara and Rubega 2010). Erection of hair-like papillae in bats driven by blood flow produces rapid changes in tongue surface area during nectar lapping (Harper et al. 2013). ...
Most flower-visiting insects employ highly-evolved organs to feed themselves rapidly and efficiently on the floral nectar. A honey bee drives its segmented tongue (glossa) covered by dense hairs reciprocatingly to load nectar. A high-speed camera system ameliorated by a microscope revealed morphological changes in glossal surfaces during live honey bees’ nectar dipping and surface configurations through the stretching of postmortem honey bees’ glossae. Both the in vivo and postmortem observations reveal that shortening and lengthening of the glossal segments perform high concordance with the erection of glossal hairs, which aids in developing deformable gaps between rows of glossal hairs during nectar trapping. A model was proposed to evaluate the nectar-intake volume considering the experimentally-measured average erection angle and tongue elongation length during nectar feeding. The theoretical results fit the experimental data well and disclose that these two factors contribute to an augmentation of nectar-intake observably. We also theoretically present that the extendible and deformable glossae have advantages for the polylectic feeding behavior.
... ej. familias Accipitridae y Ramphastidae-(Proctor y Lynch 1993).La morfología, tamaño y demás estructuras del pico han sido asociadas al uso de recursos en numerosos estudios con aves neotropicales, así como a aspectos de selección sexual, ecología, espacio acústico y radiación adaptativa(Wolf et al. 1976, Miles y Ricklefs 1984, Grant y Grant 1997, Rico-Guevara 2008, Clark 2010, Rico-Guevara y Rubega 2011, Rico-Guevara 2014, Rico-Guevara y Araya-Salas 2015. Igualmente, en muchas especies de aves el tamaño y forma del pico se encuentran bajo una fuerte presión de selección en el contexto de forrajeo, manipulación de alimento y dispersión de semillas(Grant 1968, Grant y Grant 1972, Freed et al. 1987, Grant 2003, Grenier y Greenberg 2005, Herrel et al. 2005. ...
... ej. familias Accipitridae y Ramphastidae-(Proctor y Lynch 1993).La morfología, tamaño y demás estructuras del pico han sido asociadas al uso de recursos en numerosos estudios con aves neotropicales, así como a aspectos de selección sexual, ecología, espacio acústico y radiación adaptativa(Wolf et al. 1976, Miles y Ricklefs 1984, Grant y Grant 1997, Rico-Guevara 2008, Clark 2010, Rico-Guevara y Rubega 2011, Rico-Guevara 2014, Rico-Guevara y Araya-Salas 2015. Igualmente, en muchas especies de aves el tamaño y forma del pico se encuentran bajo una fuerte presión de selección en el contexto de forrajeo, manipulación de alimento y dispersión de semillas(Grant 1968, Grant y Grant 1972, Freed et al. 1987, Grant 2003, Grenier y Greenberg 2005, Herrel et al. 2005. ...
... ej. familias Accipitridae y Ramphastidae-(Proctor y Lynch 1993).La morfología, tamaño y demás estructuras del pico han sido asociadas al uso de recursos en numerosos estudios con aves neotropicales, así como a aspectos de selección sexual, ecología, espacio acústico y radiación adaptativa(Wolf et al. 1976, Miles y Ricklefs 1984, Grant y Grant 1997, Rico-Guevara 2008, Clark 2010, Rico-Guevara y Rubega 2011, Rico-Guevara 2014, Rico-Guevara y Araya-Salas 2015. Igualmente, en muchas especies de aves el tamaño y forma del pico se encuentran bajo una fuerte presión de selección en el contexto de forrajeo, manipulación de alimento y dispersión de semillas(Grant 1968, Grant y Grant 1972, Freed et al. 1987, Grant 2003, Grenier y Greenberg 2005, Herrel et al. 2005. ...
La ecología funcional provee una información clave para la evaluación del estado de vulnerabilidad o resiliencia de los sistemas biológicos y los servicios ecosistémicos asociados a estos. Esta consideración es importante
frente a los retos actuales de manejo integral del territorio que involucran la declaración de áreas protegidas,
la restauración de procesos ecológicos y el manejo de especies invasoras, entre otros. La consideración de la
diversidad de rasgos funcionales que sustentan, directa o indirectamente, diferentes servicios ecosistémicos
y las características espaciales de la distribución potencial de los mismos, permiten el mapeo de procesos que
pueden apoyar la oferta de servicios específicos. Su conocimiento e investigación es fundamental sobre todo en los países cuya diversidad biológica es un pilar para el desarrollo socioeconómico y el bienestar humano. El reto actual consiste en aumentar la información generada a partir de rasgos funcionales que sea puesta a disposición de la comunidad científica, también traducida e integrada en recomendaciones que disminuyan la pérdida de la función ecosistémica en el territorio.
... Archerfish adjust for index of refraction when shooting water jets through the interface to catch prey (1,2), some marine copepods leap into the air to avoid predation (3)(4)(5)(6), and lizards and frogs run or skip across the water surface to escape predators (7)(8)(9). However, almost all terrestrial animals interact regularly with the air-water interface when they drink or feed (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). These animals use a wide array of mechanisms to breach the interface and transport fluid into their bodies, including viscous dipping, capillary suction, viscous suction, licking, and lapping (17). ...
Significance
Cats and dogs are assumed to drink similarly, but little is known about the actual physical mechanisms that dogs use to transport fluids when lapping. We observed the drinking behavior of a wide range of dogs across breeds and body size, and used physical experiments to mimic the motion of a dog’s tongue as it exits the water. Dogs accelerate the tongue upward more quickly than do cats, and then time their bite to coincide with the pinch-off of the column. The everyday experience of dogs as messy drinkers results from the backward curl of the tongue, which increases the size of the water column and thus enables dogs to drink more per lap than with a straight tongue.
... The drinking mechanisms of many animals have been observed and analyzed (Rico-Guevara and Rubega, 2010;Kim et al., 2012). Some scholars consider animal tongues or tongue-like devices as rigid bodies while drinking, such as the tongue of butterflies (Lee et al., 2014), shorebirds (Prakash et al., 2008), cats (Reis et al., 2010), and dogs (Crompton and Musinsky, 2011). ...
... Additionally, this sexually dimorphic weapon in hummingbirds is a direct modification of the feeding apparatus; possessing a weapon is advantageous in the mating process but may be disadvantageous for feeding (e.g., salmon: Darwin 1859; Witten and Hall 2002). Hummingbirds feed on nectar by extruding the liquid from the tongue using their bill tips (Ewald and Williams 1982;Rico-Guevara and Rubega 2011), the bill tip modifications described in this paper would impose a functional trade-off between fighting ability and feeding performance. Comparative studies to understand and quantify the costs (or lack thereof e.g., beetles: McCullough and Emlen 2013) of sexually dimorphic weapons in nature, and studies on sexual differences in feeding efficiency in species with sexually dimorphic weapons (e.g., fiddler crabs: Weissburg 1993; Mokhlesi et al. 2011) are warranted. ...
One way in which secondary sexual traits can influence differential reproductive success is by playing a key role in the outcome
of direct physical contests for mates. Here we describe an undocumented trait in a species of hummingbird with a lek mating
system, the Long-billed hermit (LBH, Phaethornis longirostris). The trait under consideration is a dagger-like structure at the bill tip, which we hypothesize is a secondary sexual trait
that functions as a sexually dimorphic weapon. We tested our hypothesis by examining 5 leks during 4 consecutive years, and
by employing morphological analyses, performance experiments, and behavioral observations. We found that 1) adult male bill
tips were longer and pointier than their counterparts in females and juvenile males, 2) juvenile males acquired dagger-like
tips during their transition to adulthood, 3) variation in bill tip morphology reflected puncture capability, and 4) males
with larger and pointier bill tips were more successful in achieving lek territory tenure. Our study provides the first evidence
of sexually dimorphic weapons in bird bills and stands as one of the few examples of male weaponry in birds. Our results suggest
a role of sexual selection on the evolution of overall bill morphology, an alternative hypothesis to the prevailing “ecological
causation” explanation for bill sexual dimorphism in hummingbirds.
Observations of maxillary (upper bill) bending in hummingbirds have been considered an optical illusion, yet a recent description of out-of-phase opening and closing between their bill base and tip suggests a genuine capacity for bill bending. We investigate bill kinematics during nectar feeding in six species of hummingbirds. We employed geometric morphometrics to identify bending zones and combined these data with measurements of bill flexural rigidity from micro-computed tomography scans to better understand the flexing mechanism. We found that the mandible remains in place throughout the licking cycle, while the maxilla undergoes significant shape deformation, such that the distal portion of the upper bill bends upwards. We propose that bill bending is a key component of the drinking mechanism in hummingbirds, allowing the coordination of bill function (distal wringing and basal expansion) and tongue function (raking/squeegeeing) during intra-oral transport. We present a fluid analysis that reveals a combination of pressure-driven (Poiseuille) and boundary-driven (Couette) flows, which have previously been thought to represent alternative drinking mechanisms. Bill bending allows for separation of the bill tips while maintaining a tightly closed middle section of the bill, enabling nectar exploitation in long and narrow flowers that can exclude less efficient pollinators.
By studying both species the results showed that the average weights of adult birds were 1445 gm in ducks. the average rate of tongue’s weight was 8.87 gm, and a relative weight of 0.61 gm, while the average weights in geese were 2374 gm, 11.28 gm, and 0.47 gm, respectively. The dorsal surface of the apex of the tongue of ducks was spoon-shaped, while the apex of the tongue of geese was round. but the ventral surface was triangular with a white plate termed the nail of the tongue in both species. The caudal part of the duck tongue makes the tongue comb which is placed in front of the lingual elevation, whereas the caudal part of the goose tongue forms the median furrow which is located at the front border of the lingual elevation. The margins of the tongue of both animals include large and small conical mechanical papillae, in addition to filiform papillae. A significant difference has been noted in the thickness of the apex and the root of the tongue between the two birds. Also, there was a significant difference in the width of the lingual elevation and root between the two birds.
The present investigation represents the first morphological description of the oropharyngeal cavity of Eurasian common moorhen. Nine oropharyngeal cavities were examined grossly and by stereomicroscope and scanning electron microscopic (SEM) observations. The tongue had a rounded apex with multiple acicular processes on its rostral and lateral borders. The dorsal lingual surface of the apex and body had a median sulcus. The papillary crest carried four caudally directed triangular conical papillae on its median part and four triangular conical papillae on each lateral part. The filiform papillary system; small papillae on apex and long papillae on the rostral part of the body while broad papillae on the caudal part of the body. The lingual root had a special appearance by presence of three areas: mucosal fossa, two lateral ridges, and rhomboidal elevated central part. The caudal border of the mound carried heart-shaped pharyngeal papillae that possessed three papillary rows. The palate had a median palatine ridge rostrally that surrounded by two lateral palatine ridges. The choanae had two equal parts: rostral tapering and wide caudal. The rostral tapering choanal part was surrounded by two longitudinal rows of caudally directed conical papillae, one on each side. There was a single transverse row of conical papillae on each side of the caudal part of the rostral tapering choanal part. The caudal wide choanal part did not encircle by any papillae. Our conclusion exhibited unique structural and functional specifications of the oropharyngeal cavity with the tongue that evident with nutritional behavior.
The honey bee, Apis mellifera ligustica, uses the specialized tongue structured by ∼120 segmental units, coated by bushy hairs, to dip varying concentration nectar flexibly at small scales. While dipping, the segmental units elongate by 20%, coordinated with rhythmical erection of hairs, the pattern of which is demonstrated to be capable of both increasing nectar intake rate and saving energy. The compliance in the segmental units allows extension of the tongue, which however, challenges the structural stability while traveling through the viscous fluid. In this combined experimental and theoretical investigation, we apply scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), micro-computed tomography scanning (micro-CT), atomic force microscopy (AFM), and mechanical models to reveal the structural and material specialisations in a bee tongue for meeting the functionally contradictive demands. We find that each segmental unit is a complex structure, which is composed of an intersegmental membrane (ISM) and a ring-like hair base (RHB), with spatially distributed discrete changes in material properties. The combination of these two components makes the tongue multifunctional, in which the ISMs characterized by resilin-rich material make the segmental units compliant, while the RHBs with rigid sclerotized material provide stable supporting for hairs. Our study may enlighten deployable mechanisms with correlative functional components, especially the microscopic mechanisms applied in viscous fluid tranport.
Statement of significance
The honey bee tongue is a versatile tool that extends to probe into varying-shaped corollas, retracting with 3,000 glossal hairs staying erected to load nectar. The combined requirement of both deformability and structural stability imposes opposing demands on structural stiffness. Here we show that glossal hairs are supported by rigid continuum ring-like hair bases, embedded in the elastic resilient intersegmental membrane, making the whole tongue both flexible and rigid at the same time. Our findings extend our understanding of relationship between morphology, material composition and biomechanics of dynamic biological surfaces, which may inspire design paradigms of multifunctional deployable mechanisms coordinating deformability and structural stability.
One of the reasons why flowering plants became the most diverse group of land plants is their association with animals to reproduce. The earliest examples of this mutualism involved insects foraging for food from plants and, in the process, pollinating them. Vertebrates are latecomers to these mutualisms, but birds, in particular, present a wide variety of nectar-feeding clades that have adapted to solve similar challenges. Such challenges include surviving on small caloric rewards widely scattered across the landscape, matching their foraging strategy to nectar replenishment rate, and efficiently collecting this liquid food from well-protected chambers deep inside flowers. One particular set of convergent traits among plants and their bird pollinators has been especially well studied: the match between the shape and size of bird bills and ornithophilous flowers. Focusing on a highly specialized group, hummingbirds, we examine the expected benefits from bill-flower matching, with a strong focus on the benefits to the hummingbird and how to quantify them. Explanations for the coevolution of bill-flower matching include 1) that the evolution of traits by bird-pollinated plants, such as long and thin corollas, prevents less efficient pollinators (e.g., insects) from accessing the nectar, and 2) that increased matching, as a result of reciprocal adaptation, benefits both the bird (nectar extraction efficiency) and the plant (pollen transfer). In addition to nectar feeding, we discuss how interference and exploitative competition also play a significant role in the evolution and maintenance of trait matching. We present hummingbird-plant interactions as a model system to understand how trait matching evolves and how pollinator behavior can modify expectations based solely on morphological matching, and discuss the implications of this behavioral modulation for the maintenance of specialization. While this perspective piece directly concerns hummingbird-plant interactions, the implications are much broader. Functional trait matching is likely common in coevolutionary interactions (e.g., in predator-prey interactions), yet the physical mechanisms underlying trait matching are understudied and rarely quantified. We summarize existing methods and present novel approaches that can be used to quantify key benefits to interacting partners in a variety of ecological systems.
This study aimed to provide a full morphological description of the
oropharyngeal cavity in the domestic geese with gross examination,
morphometric analysis and scanning electron microscopy. Eight heads of adult healthy geese were used in this study. The oropharyngeal roof had a large rostral part with five palatine ridges; one median, two paramedian and two lateral longitudinal rows of blunt tubercles bounded laterally by transverse horny lamellae of the beak. The caudal papillary region exhibited choanal and infundibular clefts, surrounded by caudally directed conical papillae. In floor, an
elongated tongue had a rounded apex with lingual nail and carried filiform papillae on its lateral edges. Each side of the lingual body carried 9 small conical papillae on the anterior part and 6 giant conical papillae on middle and posterior parts. These conical papillae were distributed among the filiform and hair-like papillae. The Posterior part of lingual body was thickened forming the lingual prominence with a transverse row of caudally directed 8-10 conical papillae forming a papillary crest. Lingual root consisted of a triangular surface surrounded by spinated borders. Caudally, an ovoid laryngeal mound with glottis is located in the pharyngeal floor, with conical papillae on its borders and transverse rows of large-sized pharyngeal papillae arranged linearly as 4-5 papillae on posterior part of the laryngeal mound. Openings of the salivary glands were observed in their corresponding region. In conclusion, the morphological characteristics of the oropharyngeal structures in geese confirmed their adaptation to the feeding habits and type of available food particles.
The present study represents the first trial to characterize the ultrastructural of five ages of Coturnix coturnix. Lingual nail had membrane that differ in number among five studied ages. Filiform papillary system had four caudally directed papillae types; small (apex, rostral, and median part of body in 1 day, body in 10 and 20 days), long (apex and rostral part of body in 10 days, tip and two lateral area in 20, 30, 40‐days, lateral border in 1 and 10 days, two lateral area of body in 40 days), broad (median area of body in 20, 30, 40 days). Scales on the ventral surface of apex, mound. Lingual sulci on the apex and body without reaching tip in 10, 20, 30, 40‐days while, in 1 day the body had ridge caudally. Three papillae on posterior part of lateral border of body. W‐shape crest had papillae on its median part while, its lateral part had two giant papillae on each side. Dorsal giant papillae terminated caudally with six processes, while ventral papillae terminated caudally with three processes. The unique root appearance, at 1 day had four papillae while in 10‐day, it had one papilla however in 20, 30, 40 days, it had T‐shaped ridge. Mound had one longitudinal row on each side of cleft and two transverse papillary rows at its caudal border and additional row at 40‐days. Our findings exposed unique structural and functional characterizations of lingual and laryngeal entrance that reflected with feeding behavior.
Research on hummingbirds over the decades has provided insights into their evolution, migration, physiology, and numerous other areas, including conservation biology. Their small size, energy demands, and high metabolic rates are some of the challenges researchers face when obtaining research samples and biologic materials from live hummingbirds. This manuscript summarizes the established literature dealing with basic methods that scientists have used when capturing, handling, and otherwise researching hummingbirds. Based on the authors’ experience, best practices for working with live hummingbirds are presented, including permitting requirements for studying live hummingbirds, trapping and marking, handling techniques, safe collection of tissue samples, first-aid measures, and euthanasia of hummingbirds, as well as processing of hummingbird specimens (e.g., necropsy and preservation).
The effectiveness of marine protected areas (MPAs) on the general health and conservation of species, habitats, and community interactions is of great interest to researchers, managers, and recreationalists. However, the ecological and behavioral diversity of vertebrate predators of southern California kelp forests limits our ability to make general conclusions about MPA effectiveness across a variety of species. Identifying and studying species with extreme feeding habits or prey-capture strategies may offer greater insight into predator-prey relationships and reveal the trophic importance of an animal in the larger community. Moray eels (family Muraenidae) have been shown to have morphological and behavioral adaptations that allow them to consume large prey whole, identifying them as important predators. From 2015-2018, we studied the health and feeding behavior of a long-lived, elusive, and benthic kelp forest predator, the California moray eel (Gymnothorax mordax). We trapped eels inside and outside of Blue Cavern Onshore State Marine Conservation Area, an MPA on the northwest side of Santa Catalina Island, CA which prohibits the take of any species. Over four years, we captured 1,736 eels. Overall, we found that morays were longer, older, heavier, had higher body condition and were found in greater abundance within the MPA. Although fish comprised the majority of their summer diet, morays outside of the MPA were consuming a more diverse set of fish, while kelp bass comprised more than half of the diet for morays inhabiting the MPA. Additionally, we found that morays within the MPA had larger relative vertical gape distances and narrower heads. Our recapture data support the high site fidelity of morays, indicating that their diet and morphology are influenced by their local community. While the majority of morays are thriving in the MPA, as suggested by their robust sizes and longevity, high abundance appears to result in higher frequencies of cannibalism, the presence of an undescribed disease, and lower growth rates. Our results suggest that the MPA affects the life history of morays and may select for an alternative feeding strategy in which eels develop larger vertical gape distances, smaller adductor muscles, and a specialized diet which is presumably influenced by the local environment. In addition, observations of cannibalistic behavior and species-specific disease provide us with important insight into natural factors that may still regulate populations removed from anthropogenic disturbances such as fishing.
Surface tension force plays a vital role when the length scale of a
system is small (i.e., in the micro/nano meter range). In the case of compliant
structures and soft substrates, the competition between interfacial energy and
elastic strain energy in the bulk gives rise to many interesting phenomena.
Elastocapillarity refers to the study of the effects of deformation of flexible
structures or soft substrates under the action of capillary forces. In contrast to
rigid structures/substrates, the liquid surface tension force at the three-phase
contact line could deform compliant structures or soft solids, thus resulting in
interesting dynamics. The elastocapillary interaction between liquid and solid can
give rise to stiction in microstructures, wrapping of droplet by flexible
structures, buckling of fibres, and ridge formation at the contact line of a droplet
on a soft substrate. Besides, recent research has shown that elastocapillarity can
aid in the manipulation of liquid flow through flexible confinements and over soft
substrates. Here, we report an extensive review of the literature on
elastocapillarity mainly focusing on the elastocapillary-based liquid transport. The
research in the field has been broadly classified into three different categories:
liquid flow in compliant microchannels, liquid flow in flexible structures, and
transport of droplets over soft elastic substrates. In each of the above cases,
theoretical understanding of the mechanism responsible for liquid transport, and
experimental studies leading to interesting results and observations are presented
and discussed. Numerical modelling of elastocapillarity phenomena is also presented.
Finally, we discuss the research challenges and future directions in the field of
elastocapillarity-based transport of liquids.
The current work considers the first anatomical description of oropharyngeal cavity of Garganey, which was performed on eight heads with the help of scanning electron microscopy (SEM). The round apex of elongated tongue has anterior spatula‐like named lingual nail. SEM of dorsal surface of lingual nail carry microtubercles and micropores on its rostral part, while its caudal part carry numerous microridges and micropores, while lateral apical surface only without lingual nail carrying filiform papillae, but its ventral surface carry exfoliated scales‐like projections. Lateral lingual tip carries numerous laterally directed hairs‐like structures. Rostral part of body carry region of small conical papillae in between them small hairs‐like papillae on its lateral surface. Middle part of body carry lingual comb on its dorsal surface, while its lateral surfaces carry region of small conical papillae in between them hairs‐like papillae in addition to filiform papillae, and large conical with small filiform papillae begin to appear laterally to the heads of lingual comb. Lateral surface of lingual prominence carry region of large conical and small filiform papillae on its rostral part, while its caudal part occupied by laterally situated spinated border from the root. Lingual root has two triangular smooth middle and spinated lateral and caudal. Laryngeal entrance divided into papillary and nonpapillary regions. Roof of oropharyngeal cavity divided into lamellar and papillary regions. Choanal cleft divided into rostral narrow ¼ and wide caudal ¾ parts. In conclusion, feeding process depend on the filter feeding mechanism that performed by the help of lateral situated papillae with lingual prominence.
The focus of the present study is to provide a full morphological description of the oropharyngeal cavity of the house sparrow. The head of six birds was prepared for gross examination and by stereo and electron microscopy. The bifid lingual apex has multiple long, rostrally directed needle-like processes. The lateral border of the apex carries rostromedially directed needle-like processes. The dorsal lingual surface of the apex and body carries numerous caudomedially directed filiform papillae and many orifices of lingual salivary glands. The lingual body is divided into two parts: rostral and caudal. The caudal part is divided into two laterally elevated regions by a median groove, while the rostral part is bounded laterally by a rostrodorsally directed papillary row, which on SEM is formed from two rows. On SEM, the lingual root has many orifices of posterior salivary glands. The pharyngeal papillary row is located at the caudal border of the laryngeal mound, but this single papillary row is formed from two rows at SEM magnification. The laryngeal cleft continues caudally as a laryngeal fissure bounded by two longitudinal rows of caudally directed papillae; at high SEM magnification, this fissure is divided into two halves by a median ridge which carries caudally directed papillae on its posterior part. The choanal cleft proceeds rostrally by the median tubercle. There are a small number of orifices of palatine salivary glands. The morphological characters of the oropharyngeal cavity of the sparrow confirm its adaptation to surrounding environmental conditions and available food particles.
The major salivary glands of birds develop by branching or elongation of the epithelial cords. The development of the minor salivary glands in form of the lingual glands has never been described. Among birds, only Anatidae have three types of the lingual glands: rostral, caudo-lateral, and caudo-medial lingual glands. The study aims to characterize the manner and rate of the lingual glands development in the domestic duck and their topographical arrangement relative to the hyoid apparatus. The study reveals that all three types of the lingual glands develop by branching. We describe five stages of the lingual glands development in the domestic ducks: prebud, initial bud, pseudoglandular, canalicular, and terminal bud stage. The pattern of the lingual glands development in birds is similar to that described for mammals, with the exception, that the terminal buds are formed at the same time as the lumen of the glands. Generally, the rostral lingual gland starts to branch earlier than the caudal lingual glands. The 3D-reconstruction shows the location and direction of lingual gland development relative to the entoglossal cartilage and basibranchial bone. Light microscopy and scanning electron microscopy allow to characterize the histogenesis of the embryonic epithelium into glandular epithelium. At a time of hatching only secretory units of caudal lingual glands resemble the secretory units of the adult domestic duck. The rostral and caudo-lateral lingual glands are arranged on the sides of the entoglossal cartilage and basibranchial bone and caudo-madial lingual glands are located over the basibranchial bone. We suggest that such an arrangement of the lingual glands in the domestic duck is important during food intake and responsible for reduction of friction and formation of food bites.
Although negligible at large scales, capillary forces may become dominant for submillimetric objects. Surface tension is usually associated with the spherical shape of small droplets and bubbles, wetting phenomena, imbibition, or the motion of insects at the surface of water. However, beyond liquid interfaces, capillary forces can also deform solid bodies in their bulk, as observed in recent experiments with very soft gels. Capillary interactions, which are responsible for the cohesion of sandcastles, can also bend slender structures and induce the bundling of arrays of fibers. Thin sheets can spontaneously wrap liquid droplets within the limit of the constraints dictated by differential geometry. This review aims to describe the different scaling parameters and characteristic lengths involved in elastocapillarity. We focus on three main configurations, each characterized by a specific dimension: three-dimensional (3D), deformations induced in bulk solids; 1D, bending and bundling of rod-like structures; and 2D, bending and stretching of thin sheets. Although each configuration deserves a detailed review, we hope our broad description provides a general view of elastocapillarity.
In times of short product life cycles, unstable market demands and global competition, innovation management has become a crucial part of business today. New ways for generating ideas and thus innovations are constantly looked for in order to guarantee long term success. Generating innovations by using the results of 3.8 billion years of evolution, assuming that the implementation of those optimized biological structures into technology implies beneficial developments, is the main purpose of biomimetics also called bionics. Despite the various well known inventions and innovations generated by learning from biological models, biomimetics still seems like a relatively new topic in the context of innovation management and is employed very seldom by non-biologists like designers or engineers. One reason for this is the lack of detailed supporting contents and methods in present bionic approaches. The aim of this work is the improvement and completion of identified gaps in present bionic approaches. For this, a new, general bionic concept including a detailed guideline with appropriate methods and tools is provided and validated. As one important part the iSEE (iterative semantic examination) process was created, which supports the identification of biological models. Furthermore it is investigated, if it is possible to enable biomimetics in development processes for novices. A workshop with experts for innovations processes was carried out, focussing on a concrete topic to testify the concept in a realistic environment. The evaluation was carried out by a qualitative user survey whereby every process step and the concept in general has been assessed by provided questionnaires. Evaluation results show that the usability and usefulness of the developed concept could be validated and confirmed by experts. Several annotations are made for further improvements and the concept’s importance for development. Enabling biomimetics for common users can thus be realized in the future using the developed guideline. Further advancements including software supported completions are proposed for future research projects.
The study of animals in the wild offers opportunities to collect relevant information on their natural behavior and abilities to perform ecologically relevant tasks. However, it also poses challenges such as accounting for observer effects, human sensory limitations, and the time intensiveness of this type of research. To meet these challenges, field biologists have deployed camera traps to remotely record animal behavior in the wild. Despite their ubiquity in research, many commercial camera traps have limitations, and the species and behavior of interest may present unique challenges. For example, no camera traps support high-speed video recording. We present a new and inexpensive camera trap system that increases versatility by separating the camera from the triggering mechanism. Our system design can pair with virtually any camera and allows for independent positioning of a variety of sensors, all while being low-cost, lightweight, weatherproof, and energy efficient. By using our specialized trigger and customized sensor configurations, many limitations of commercial camera traps can be overcome. We use this system to study hummingbird feeding behavior using high-speed video cameras to capture fast movements and multiple sensors placed away from the camera to detect small body sizes. While designed for hummingbirds, our application can be extended to any system where specialized camera or sensor features are required, or commercial camera traps are cost-prohibitive, allowing camera trap use in more research avenues and by more researchers.
The present study represents the first definitive anatomical description of the oropharyngeal cavity of the coot Fulica atra. For this purpose, the organs of six birds were prepared to examine grossly and by SEM and stereomicroscope. The oval lingual apex had multiple overlapping branched acicular processes on its anterior and lateral border. The lingual apex and body had multiple caudally directed filiform-like papillae. By stereomicroscopy, the lingual root had a characteristic appearance and consisted of four parts. The openings of the anterior glands were present on the dorsal lingual surface of the body, while the projected papillae with wide openings of the posterior glands were present on the dorsal surface of lingual root. There was a row of caudally directed pharyngeal papillae at the caudal border of the laryngeal mound. Grossly, the pharyngeal papillae arrangement took a W-shape, while by stereomicroscopy was observed to be heart shape. The palate was divided into two regions: a small rostral non-papillary and a large caudal papillary region, but the rostral region was characterized by the presence of three longitudinal ridges. The papillary crest had two paramedian longitudinal papillary rows, which continued caudally until the beginning of the third median row. The freely distributed papillae took a caudolateral direction, while the papillae encircling the rostral part of choanal cleft took a caudomedial direction. There was a transverse papillary row between the two parts of choanal cleft. There was a transverse papillary row between the caudal border of the infundibular cleft and oesophagus.
A complete understanding of the feeding structures is fundamental in order to study how animals survive. Some birds use long and protrusible tongues as the main tool to collect their central caloric source ( e.g. woodpeckers and nectarivores). Hummingbirds are the oldest and most diverse clade of nectarivorous vertebrates, being a perfect subject to study tongue specializations. Their tongue functions to intraorally transport arthropods through their long bills and enables them to exploit the nectarivorous niche by collecting small amounts of liquid, therefore it is of vital importance to study its anatomy and structure at various scales. I focused on the portions of the hummingbird tongue that have been shown to be key for understanding their feeding mechanisms. I used histology, transmission and scanning electron microscopy, microCT, and ex-vivo experiments in order to advance the comprehension of the morphology and functioning of the hummingbird feeding apparatus. I found that hummingbird tongues are composed mainly of thin cornified epithelium, lack papillae, and completely fill the internal cast of the rostral oropharyngeal cavity. Understanding this puzzle-piece match between bill and tongue will be essential for the study of intraoral transport of nectar. Likewise, I found that the structural composition and tissue architecture of the tongue groove walls provide the rostral portion of the tongue with elastic properties that are central to the study of tongue-nectar interactions during the feeding process. Detailed studies on hummingbirds set the basis for comparisons with other nectar-feeding birds and contribute to comprehend the natural solutions to collecting liquids in the most efficient way possible.
By specialising on specific resources, species evolve advantageous morphologies to increase the efficiency of nutrient acquisition. However, many specialists face variation in resource availability and composition. Whether specialists respond to these changes depends on the composition of the resource pulses, the cost of foraging on poorly matched resources, and the strength of interspecific competition. We studied hummingbird bill and plant corolla matching during seasonal variation in flower availability and morphology. Using a hierarchical Bayesian model, we accounted for the detectability and spatial overlap of hummingbird-plant interactions. We found that despite seasonal pulses of flowers with short-corollas, hummingbirds consistently foraged on well-matched flowers, leading to low niche overlap. This behaviour suggests that the costs of searching for rare and more specialised resources are lower than the benefit of switching to super-abundant resources. Our results highlight the trade-off between foraging efficiency and interspecific competition, and underline niche partitioning in maintaining tropical diversity.
My research aims to answer the questions: How do hummingbirds feed? And, how do the mechanics of feeding define the limits and adaptive values of feeding behaviors? I meticulously study every step of nectar capture and ingestion. My dissertation chapters are organized following a morpho-functional and feeding sequence approach: 1) Feeding Apparatus Morphology; with emphasis on the understudied morphology of the tongue grooves and bill tongue coupling. 2) Tongue Tip Dynamics; how hummingbird tongues entrap nectar. 3) Tongue Grooves Functioning: how the tongue acts as an elastic micropump while collecting nectar. 4) Bill Tip Mechanics; internal bill structures that aid in offloading nectar from the tongue. 5) Intraoral Transport: how the nectar flows inside the bill to the throat where it can finally be swallowed. My results demonstrate that capillarity equations are unsuitable to calculate energy intake rate, which is the building unit of foraging theories; therefore a development of a new theoretical framework to study hummingbird energetics and foraging ecology is needed. I describe previously unknown methods of tongue-based nectar collection, report undocumented tongue and bill structures, and offer the first test of intraoral transport hypotheses. I followed the scientific method cycle of deduction and induction. To understand the determinants of hummingbird feeding mechanics in an ecological context, I tested biophysical model predictions using data from wild birds. Elucidating the drinking mechanism of hummingbirds will facilitate downstream calculations of the rates at which birds can obtain nectar along several environmental axes (e.g. altitudinal and latitudinal ranges, migrations, corolla morphology, etc.). This will in turn inform how and where the limits of nectar uptake have shaped the distribution, ecology and evolution of hummingbirds. With their enchanting appeal and unique physical capabilities, hummingbirds captivate people of all ages. As such, they serve as ambassadors to the natural world, fostering public appreciation for scientific and conservation efforts aimed at preserving these fascinating birds, and the biodiversity upon which they depend.
The aim of this investigation was to describe the morphological characters of the tongue of two predatory birds with similar feeding preferences, i.e. the common kestrel and Hume's tawny owl. Descriptive information on the lingual morphology of these two birds, particularly Hume's tawny owl, is incomplete. We found that the lingual apex of the owl has an oval, concave, shovel-like form with a bifid lingual tip, while that of the kestrel has the shape of a horny tip-like spoon with a central process in addition to there being several filiform-like papillae on the dorsal surface of the apex and body. In the owl, the dorsal surface of the apex and body is subdivided into four U-shaped regions: lingual tip, two lateral regions and a median region. The two lateral regions are characterized by the presence of papillae and several openings of lingual glands, while the median region carries filiform-like papillae. In both birds, the papillary crest is located between the body and root. In the kestrel, there is an additional row of papillae rostral to crest, while in the owl there is a rostral lateral extension of papillae on the lateral lingual surface so the distribution pattern has a W-shape. In the kestrel, the posterior part of lingual body has several openings of glands, while the root lacks glands completely, although it has many taste buds. In the owl, the lingual root is folded and has a large number of gland openings. In the kestrel caudally to the glottis, there are two paramedian transverse rows of pharyngeal papillae with a pair of median huge papillae, while in the owl, there is only one transverse row of papillae. The dorsal and ventral lingual surfaces of both birds are lined with non-keratinized stratified squamous epithelium.
Various nectarivorous animals apply bushy-hair-equipped tongues to lap nectar from nectaries of flowers. A typical example is provided by the Italian honeybee (Apis mellifera ligustica), who protracts and retracts its tongue (glossa) through a temporary tube, and actively controls the erectable glossal hairs to load nectar. We first examined the microstructure of the honeybee’s glossal surface, recorded the kinematics of its glossal hairs during nectar feeding process and observed the rhythmical hair erection pattern clearly. Then we measured the wettability of the glossal surface under different erection angles (EA) in sugar water of the mass concentration from 25 to 45%, mimicked by elongating the glossa specimens. The results show that the EA in retraction approximately remains stable under different nectar concentrations. In a specific concentration (35, 45, or 55%), the contact angle decreases and glossal surface area increases while the EA of glossal hairs rises, the glossa therefore could dynamically alter the glossal surface and wettability in foraging activities, not only reducing the energy consumption for impelling the nectar during tongue protraction, but also improving the nectar-trapping volume for feeding during glossa retraction. The dynamic glossal surface with switchable wettability regulated by erectable hairs may reveal the effective adaptation of the honeybee to nectar intake activities.
Avian keratin disorder produces an abnormal beak growth. This disorder has been reported in several bird species in America and Europe, but there are no reports in hummingbirds. Here we report a White-eared Hummingbird affected by this disorder, which was captured in San Bernardino Lagunas, Vicente Guerrero, Puebla. It is possible that hummingbirds affected by this this disorder negatively affect feeding and pollination.
The honeybee's drinking process has generally been simplified because of its high speed and small scale. In this study, we clearly observed the drinking cycle of the Italian honeybee using a specially designed high-speed camera system. We analysed the pattern of glossal hair erection and the movement kinematics of the protracting tongue (glossa). Results showed that the honeybee used two special protraction strategies to save energy. First, the glossal hairs remain adpressed until the end of the protraction, which indicates that the hydraulic resistance is reduced to less than 1/3 of that in the case if the hairs remain erect. Second, the glossa protracts with a specific velocity profile and we quantitatively demonstrated that this moving strategy helps reduce the total energy needed for protraction compared with the typical form of protraction with constant acceleration and deceleration. These findings suggest effective methods to optimise the control policies employed by next-generation microfluidic pumps.
Pumping is a vital natural process, imitated by humans for thousands of years. We demonstrate that a hitherto undocumented mechanism of fluid transport pumps nectar onto the hummingbird tongue. Using high-speed cameras, we filmed the tongue-fluid interaction in 18 hummingbird species, from seven of the nine main hummingbird clades. During the offloading of the nectar inside the bill, hummingbirds compress their tongues upon extrusion; the compressed tongue remains flattened until it contacts the nectar. After contact with the nectar surface, the tongue reshapes filling entirely with nectar; we did not observe the formation of menisci required for the operation of capillarity during this process. We show that the tongue works as an elastic micropump; fluid at the tip is driven into the tongue's grooves by forces resulting from re-expansion of a collapsed section. This work falsifies the long-standing idea that capillarity is an important force filling hummingbird tongue grooves during nectar feeding. The expansive filling mechanism we report in this paper recruits elastic recovery properties of the groove walls to load nectar into the tongue an order of magnitude faster than capillarity could. Such fast filling allows hummingbirds to extract nectar at higher rates than predicted by capillarity-based foraging models, in agreement with their fast licking rates.
© 2015 The Author(s).
A new study shows that birds plucking anthers of the Melastome, Axinaea, demonstrate a novel bird pollination mechanism. Each stamen of Axinaea offers a nutrient-rich, berry-like food body that, when bitten, releases a puff of pollen allowing transfer to stigmas by wind or the pollen-dusted bird.
Sexual size dimorphism occurs throughout the animal kingdom, and its ecological and evolutionary causes and implications have been intensively studied. Sex-specific
differences in bill curvature are known in several species of birds, including some tropical hummingbirds. Despite the importance of bill shape for foraging, comparative studies of sexual dimorphism of bill shape are few. We quantified bill shape in two temperate hummingbird species, Black-chinned Hummingbird (Archilocus alexandri) and
Ruby-throated Hummingbird (A. colubris) and compared patterns of sexual shape dimorphism. Several commonly used bill-curvature indices yielded contrasting results; one found differences between species and sexes, a second identified no differences in curvature, and a circle-curvature approach revealed shape differences between species and between the sexes. By contrast, landmark-based geometric morphometric methods identified significant differences in sexual shape dimorphism and also revealed that Ruby-throated Hummingbirds exhibited significant sexual differences in shape, whereas Black-chinned Hummingbirds did not. Female Ruby-throated Hummingbirds exhibited relatively greater bill curvature than males, a pattern consistent with observations of some tropical
hummingbirds. Although the causes of differences in bill-shape dimorphism between Black-chinned and Ruby-throated hummingbirds remain unclear, we hypothesize that it may be attributable to differences in the structure of the community in which each species breeds and the interplay between inter- and intraspecific competition for resources in these communities. Finally, we recommend that future studies of bill shape include geometric morphometric approaches because they are better suited than univariate approaches for identifying more complex shape differences within and among species.
This two-year study seeks to quantify the relations of the breeding, molt, and population movements of hummingbirds, with the flowering seasons of their foodplants, at La Montura, a site in premontane rain forest at 1000 m on the Caribbean slope of Costa Rica. The community comprises 22 hummingbird species (9-10 residents, 5-6 regular seasonal visitors, the rest rare to accidental), that collectively visit at least 70 species of plants, ca. 50 of which they pollinate. Patterns of flower visitation by the birds allow partitioning of the community into subcommunities, each with its own seasonal rhythm. These are: (a) Lancebill Subcommunity: the Green-fronted Lancebill (Doryfera ludovicae) and five species of large shrubby epiphytes, and probaby several bromeliads. Morphologically, the bird's long, slender, nearly straight bill and the flowers' correspondingly shaped corolla tubes characterize this subcommunity. The five principal foodplants bloomed in a nearly perfectly staggered sequence through the study period; breeding in D. ludovicae coincided with periods of greatest flower abundance, molt with intermediate flower availability, (b) Hermit Subcommunity: chiefly the Green Hermit (Phaethornis guy) with its long, decurved bill, and 19 understory and subcanopy flowers with correspondingly shaped corollas. Flower availability is high during breeding, peaks during the period of molt-breeding overlap, and declines during molt and quiescent periods; the species of Heliconia appear to supply critical nectar resources for breeding. P. guy's foodplants show staggered blooming sequences when the bird's breeding and nonbreeding periods are analyzed separately. Also included here is the White-tipped Sicklebill (Eutoxeres aquila), whose visits to the study area are linked to the blooming of a single foodplant. (c) Heliodoxa-Marcgravia Subcommunity: the Green-fronted Brilliant (Heliodoxa jacula) and three species of sphingid- or bat-pollinated Marcgravia, about which the bird's breeding and molting cycles appear to be organized. The three Marcgravia species bloom in a staggered sequence that is exploited by H. jacula, but this cannot reflect a coevolutionary relationship as the hummingbird is a nectar thief, (d) "Generalized" Subcommunity: various small- to medium-sized, straight-billed hummingbirds, and flowers with straight, short- to medium-length corollas. Sufficient overlap in flower visitation exists within this assemblage to preclude further subdivision. The principal hummingbird species (Lampornis hemileucus, Eupherusa nigriventris, Elvira cupreiceps) breed in close association with the blooming of a series of canopy epiphytes, mostly in the family Ericaceae. Many individuals of the latter two species, plus Colibri delphinae, emigrate following breeding and at least the start of molt; their places are taken by several species of post- breeding seasonal visitors from other elevations, which mostly exploit the flowers of the abundant understory treelet Cephaelis elata. Most La Montura hummingbirds breed from the mid- to late wet season, through the early dry season, roughly October through March, and molt from March through June, into the early rainy season. Males of many species molt one to two months ahead of females. The cycle of H. jacula is displaced one to two months earlier than those of most species, while that of P. guy is nearly the opposite: breeding April-September, molting July-November. Differences in seasonality in other humming-bird-flower communities reflect different climatic regimes and taxonomic affinities-e.g., in all areas Ericaceae bloom mainly in the wet season, Heliconia mostly June-August. The various hummingbird-flower communities in the wet forests of Costa Rica show similar divisions into subcommunities, given different species richnesses and taxonomic affinities. In dry forest and second growth, most or all species pertain to the generalized subcommunity. The relation between plant-pollinator interactions and flowering seasons is reassessed in the light of changing nectar demands of the birds due to breeding and molt. It is concluded that competition for pollinators may be an important selective force in the spacing of flowering seasons, but that its intensity varies according to the annual cycles of the pollinators, and cannot be assessed properly without taking the pollinators' biology into account. Finally, based on ecological and biogeographical evidence, it is argued that many (but by no means all) of the bird-flower interactions in the La Montura community represent true coevolved mutualisms. /// Este estudio de dos años, pretende cuantificar la relación de la reproducción, muda y movimientos de poblaciones de colibríes con las épocas de floración de sus plantas alimenticias, en La Montura, un sitio de la selva lluviosa premontana a 1.000 m de altura en la ladera caribeña costarricense. La comunidad está compuesta por 22 especies de colibríes (9-10 residentes; 5-6 visitantes regulares estacionales y el resto raros o accidentales) que visitan en forma collectiva el menos 70 especies de plantas, de las cuales polinizan casi 50. Los patrones de las aves para visitar las flores, permiten dividir la comunidad en subcomunidades, cada una con su propio ritmo estacional. Estas son: a- Subco- munidad Pico de Lanza: el pico de lanza mayor (Doryfera ludovicae) y cinco especies de arbustos epífitos grandes y probablemente varias bromelias. Esta subcomunidad está caracterizada morfológicamente por el pico largo fino y casi recto, que corresponde con la forma del tubo de las corolas de las flores. Las cinco plantas principales de alimentación florecen en secuencia casi perfecta a lo largo del período de estudio; la temporada de reproducción de D. ludovicae coincide con la gran abundancia de flores; la muda con disponibilidad intermedia de flores. b- Subcomunidad Ermitaño: Comandada por el ermitaño verde (Phaethornis guy) con su pico largo, curvado hacia abajo y 19 flores con sus corolas de forma similar del sotobosque ("understory") y del subdosel bajo las copas de los árboles ("subcanopy"). La disponibilidad de flores es alta durante la reproducción, teniendo su pico máximo durante el período en que la muda y reproducción se superponen, y declina durante la muda y los períodos de poca actividad ("quiescent"); las especies Heliconia parecen proveer recursos de néctar críticos para reproducir. Las plantas de las cuales se alimenta P. guy florecen en secuencia una tras otra cuando se analizan separadamente los períodos de reproducción y no-reproducción del ave. También se incluye acá al Pico de hoz colioliva (Eutoxeres aquila) cuyas visitas al área de estudio entuvieron relacionadas al florecimineto de una sola planta de alimentación. c- Subcomunidad Heliodoxa-Marcgravia: el colibrí jacula (Heliodoxa jacula) y tres especies de Marcgravia, polinizadas por polillas de la familia Sphingidae o murciélagos, sobre las cuales parece estar basado el ciclo de reproducción y muda del ave. Las tres especies de Marcgravia florecen en una secuencia que es utilizada por H. jacula, pero esto no refleja una relación de coevolución, ya que el colibrí es un Iadrón de néctar, d- Subcomunidad "Generalizada": varios picaflores de tamaño pequeño a mediano, de pico recto y flores de corola recta corta o mediana. En este grupo existe suficiente superposición en las visitas a las flores, lo cual imposibilita mayores subdivisiones. Las principales especies de picaflores (Lampornis hemileucus, Eupherusa nigriventris, Elvira cupreiceps) reproducen en asociación íntima con una serie de epífitas de las copas de los árboles mayormente de la familia Ericaceae. Muchos individuos de estas dos últimas especies, además de Colibri delphinae emigran luego de la reproducción o como máximo cuando comienza la muda; sus lugares son ocupados por varias especies de vistantes post-reproductivos de otras elevaciones, que mayormente utilizan las flores abundantes del arbolito Cephaelis elata, del nivel de vegetación inferior. La mayoría de los picaflores de La Montura reproducen desde la mitad o final de la estación húmeda hasta el principio de la temporada seca, aproximadamente desde octubre hasta marzo y mudan desde marzo hasta junio, cuando comienza la estación de las lluvias. Machos de muchas especies mudan uno o dos meses antes que las hembras. El ciclo de H. jacula está desplazado de uno a dos meses antes que el de la mayoría de las especies, mientras que el de P. guy es casi lo opuesto: reproduce entre abril y septiembre y muda entre julio y noviembre. Las diferencias en las estaciones en otras comunidades de flores y picaflores refleja régimenes climáticos diferentes y afinidades taxonómicas por ejemplo en todas las áreas las Ericáceas florece mayormente en la estación húmeda y Heliconia de junio a agosto. Las diversas comunidades de flores y picaflores en los bosques húmedos de Costa Rica muestran divisiones en subcomunidades similares, habiendo diferentes riquezas de especies y afinidades taxonómicas. En bosque seco y vegetación secundaria, la mayoría o todas las especies pertenecen a la subcomunidad generalizada. La relación entre la interacción planta-polinizador y temporada de floración está reevaluada a la luz de los cambios en las demandas de néctar de las aves debido a la reproducción y muda. Se concluye que la competencia por polinizadores puede ser una fuerza selectiva de importancia en la temporada de estaciones de floración, pero cuya intensidad varía de acuerdo con el ciclo anual de los polinizadores, y no puede serpropiamente determinado sin tomar en cuenta la biologia de los polinizadores. Fi- nalmente basandose en evidencias ecol6gicas y biogeograficas, se discute que muchas (pero por cierto no todas) las interacciones ave-flor en la comunidad de La Montura representan verdaderos mutualismos coevolucionados.
Recognizes three distinct components of flower function: attraction, reward, and filtering mechanisms, and discusses their functioning in an ecological context, and as they relate to the genetic system or 'pollination unit' of the plant. Discusses nectar-feeding birds (not only morphological, but ecological and behavioral specializations to flowers as a food source). Different bird groups vary widely in their degrees of specialization for flower-feeding; bird-flower coevolution has followed very different courses, and has led to widely divergent ecological systems in different geographical areas. The hummingbirds are the most specialized avian nectarivores, although they are approached in this regard by some members of certain passerine groups, notably among the sunbirds. Several groups of passerine nectarivores also occur with the hummingbirds in many New World areas. Patterns of ornithophily and nectarivory are examined in detail for this area, concentrating on Southern Central America, especially Costa Rica. The altitudinal and geographical distributions of the two main groups of hummingbirds, the hermits and nonhermits, differ, as are the taxonomic and ecological affinities of their primary foodplants. Hermits are most numerous in wet lowlands and the adjacent foothills, and are primarily associated with large monocotyledonous herbs, notably Heliconia. Nonhermits reach their greatest taxonomic and ecological diversity in the lower middle elevations, and are the only group present at high elevations; they seem to have coevolved with the flowers of a variety of dicot families, and the bromeliads among the monocots. Passerine nectarivores occur primarily as parasites on the hummingbird-flower system (Coerebidae) and are important as pollinators only in seasonally dry areas when the hummingbirds are poorly represented.-from Author nectar feeding birds Costa Rica hummingbirds hermits Heliconia Coerebidae
Vertical jumps of fishing spiders (Dolomedes sp.) from the water surface have been pre- sumed to be evasive behaviors directed against predatory fish. We used high-speed videography to analyze the jumps of fishing spiders and then constructed a numerical model to assess the effectiveness of these jumps in evading predatory strikes by trout. Jump height (mean 5 3.7 cm) and duration (mean 5 0.17 sec) were similar across spider masses (0.05-0.66 g) but latency to jump increased significantly with mass. To accomplish jumps of similar height, more massive spiders had to generate more force during the propulsive phase of the jump than did smaller spiders; and the contribution of fluid drag to the total force used in jumping was substantially greater for large spiders than for smaller ones. Our model juxtaposing the jumps of spiders and the attacks of trout revealed that jump heights and durations were inadequate: only the most lethargic strikes by trout could be successfully evaded by jumping vertically from the water surface.
other species. I also present the results of ex- tensive field observations on flower choice by hummingbirds, and consider the taste and color stimuli presented by those flowers vis- ited by hummingbirds. Hopefully, compar- ing the results of field and laboratory studies will permit a more realistic evaluation of the role of taste and color preferences in food choice by hummingbirds, and a better under- standing of the coevolution of hummingbirds and the flowers they pollinate.
We present the results of a combined experimental and theoretical investigation of the dynamics of water-walking insects and spiders. Using high-speed videography, we describe their numerous gaits, some analogous to those of their terrestrial counterparts, others specialized for life at the interface. The critical role of the rough surface of these water walkers in both floatation and propulsion is demonstrated. Their waxy, hairy surface ensures that their legs remain in a water-repellent state, that the bulk of their leg is not wetted, but rather contact with the water arises exclusively through individual hairs. Maintaining this water-repellent state requires that the speed of their driving legs does not exceed a critical wetting speed. Flow visualization reveals that the wakes of most water walkers are characterized by a series of coherent subsurface vortices shed by the driving stroke. A theoretical framework is developed in order to describe the propulsion in terms of the transfer of forces and momentum between the creature and its environment. The application of the conservation of momentum to biolocomotion at the interface confirms that the propulsion of water walkers may be rationalized in terms of the subsurface flows generated by their driving stroke. The two principal modes of propulsion available to small water walkers are elucidated. At driving leg speeds in excess of the capillary wave speed, macroscopic curvature forces are generated by deforming the meniscus, and the surface behaves effectively as a trampoline. For slower speeds, the driving legs need not substantially deform the surface but may instead simply brush it: the resulting contact or viscous forces acting on the leg hairs crossing the interface serve to propel the creature forward.
Aim We review several aspects of the structure of regional and local assemblages of nectar‐feeding birds and bats and their relationships with food plants to determine the extent to which evolutionary convergence has or has not occurred in the New and Old World tropics.
Location Our review is pantropical in extent and also includes the subtropics of South Africa and eastern Australia. Within the tropics, it deals mostly with lowland forest habitats.
Methods An extensive literature review was conducted to compile data bases on the regional and local species richness of nectar‐feeding birds and bats, pollinator sizes, morphology, and diets. Coefficients of variation (CVs) were used to quantify the morphospace occupied by the various families of pollinators. The extent to which plants have become evolutionarily specialized for vertebrate pollination was explored using several criteria: number and diversity of growth forms of plant families providing food for all the considered pollinator families; the most common flower morphologies visited by all the considered pollinator families; and the number of plant families that contain genera with both bird‐ and bat‐specialized species.
Results Vertebrate pollinator assemblages in the New World tropics differ from those in the Old World in terms of their greater species richness, the greater morphological diversity of their most specialized taxa, and the greater degree of taxonomic and ecological diversity and morphological specialization of their food plants. Within the Old World tropics, Africa contains more specialized nectar‐feeding birds than Asia and Australasia; Old World nectar‐feeding bats are everywhere less specialized than their New World counterparts.
Main conclusions We propose that two factors – phylogenetic history and spatio‐temporal predictability (STP) of flower resources – largely account for hemispheric and regional differences in the structure of vertebrate pollinator assemblages. Greater resource diversity and resource STP in the New World have favoured the radiation of small, hovering nectar‐feeding birds and bats into a variety of relatively specialized feeding niches. In contrast, reduced resource diversity and STP in aseasonal parts of Asia as well as in Australasia have favoured the evolution of larger, non‐hovering birds and bats with relatively generalized feeding niches. Tropical Africa more closely resembles the Neotropics than Southeast Asia and Australasia in terms of resource STP and in the niche structure of its nectar‐feeding birds but not its flower‐visiting bats.
We examined whether sexual differences in trophic morphology are associated with sexual differences in foraging behavior through two laboratory experiments on rufous hummingbirds (Selasphorus rufus) designed to compare probing abilities (maximum extraction depths) and handling times of sexes at flowers. Bills of female S. rufus are about 10.5% longer than bills of males, and this difference was associated with sexual differences in foraging abilities. Maximum extraction depths of female S. rufus were significantly greater than those of males, and no overlap between the sexes was observed. Moreover, handling times of females were shorter than handling times of males at flowers having longer corollas (15 mm). Thus, because of their longer bills, female S. rufus have the potential to feed from longer flowers than males, and can do so more quickly. We suggest that no single mechanism is responsible for the evolution of sexual dimorphism in bill lengths of hummingbirds, but rather that the dimorphism probably reflects the combined effects of reproductive role division and intersexual food competition, and possibly, sexual selection.
In the context of a recently published phylogenetic estimate for 151 hummingbird species, we provide an expanded informal taxonomy, as well as a formal phylogenetic taxonomy for Trochilidae that follows the precepts of the PhyloCode, but remains consistent with the hierarchical nomenclature of the Linnaean system. We compare the recently published phylogenetic hypothesis with those of prior higher-level and more taxonomically circumscribed phylogenetic studies. We recommend the recognition of nine new clade names under the PhyloCode, eight of which are consistent with tribes and one with a subfamily under the Linnaean system.
In Costa Rica's humid, Caribbean lowlands, we used the doubly-labeled water (DLW) technique to measure field metabolic rate (FMR) and water influx of free-living Crowned Woodnymphs (Thalurania colombica) (mean mass = 4.90 g) and Bronze-tailed Plumeleteers (Chalybura urochrysia) (mean mass = 7.23 g). FMR averaged 37.9 kJ/day in woodnymphs (n = 9) and was 57.9 kJ/day in a single plumeleteer. The former value is 26% higher than expected from the birds' mass, based on other DLW studies. Water influx averaged 2,392 ml/(kg·day) in woodnymphs (n = 12) and 2,001 ml/(kg·day) in plumeleteers (n = 2). These are the highest water flux rates measured for any bird and are equivalent to turning over, respectively, 366% and 304% of the birds' total body water content each day.
Floral nectars of bird-pollinated plants are relatively dilute. One hypothesis proposed to explain this concerns the difficulty for birds of drinking nectar of high viscosity. We examined the effects of viscosity, separately from those of sugar concentration, on feeding by captive whitebellied sunbirds (Cinnyris talatala). Viscosities of artificial nectar (sucrose solutions ranging in concentration from 0.25 to 1.5 mol/l) were altered with Tylose, an inert polysaccharide. Food consumption was measured over 3 h, and lick frequency and duration were recorded using photodetection devices on feeding apertures too small for the bill but large enough for the extended tongue. Volumetric intake rates (ml/s) were inversely proportional to nectar viscosity, and were similar over the range of sucrose concentrations when viscosity was held constant. Sucrose intake rates (mg/s) remained the same on pure sucrose solutions, but they decreased with increasing viscosity at a constant sucrose concentration. Lick frequencies and tongue loads were reduced at high viscosities, and lick duration increased, which confirms that sunbirds take longer to ingest viscous solutions. Licking behavior was remarkably similar in birds feeding on different sucrose concentrations if viscosity was held constant. Nectar ingestion rate is determined by viscosity; however, total food intake is mainly modulated by sugar concentration. Similar effects of food viscosity have been observed in insects that suck nectar.
This contribution aims at improving the understanding of sap flow measurements in trees. Infrared heat field images taken around heating needles in sap transporting tree trunks are characterized by isotherms of elliptic shape with the heating needle in the lower focus. Increasing sap flow increases the eccentricity of the elliptic heat field. This dynamics of ellipses provides a simplified experimental-mathematical approach for the understanding and evaluation of the otherwise very complicated heat transfer- and distribution-problem involved. The results obtained are used to discuss criteria for possible improved positioning patterns for needle sensors aimed for sap flow calculation using the dynamics of ellipses. Images infrarouges des champs de chaleur autour d'un radiateur linéaire dans les troncs des arbres : que peut-on apprendre au sujet de la mesure du flux de sève ?. Cet article vise à améliorer la compréhension des mesures du flux de sève dans les arbres. Des images infrarouges prises autour des aiguilles de chauffage dans les troncs transportant la sève ont été caractérisées par des isothermes de forme elliptique avec l'aiguille chauffante dans le foyer le plus bas. L'accroissement du flux de sève accroît l'excentricité du champ de chaleur elliptique. Ces dynamique des ellipses fournissent une approche expérimentale et mathématique simplifiée pour la compréhension et l'évaluation autrement très compliquée du problème du transfert de chaleur. Les résultats obtenus sont utilisés pour juger de l'exactitude de la dissipation de la chaleur (HD) et de la déformation du champ de chaleur (HDF), des mesures techniques et discuter des critères pour une possible amélioration des modèles de positionnement des aiguilles détecteurs visant à calculer le flux de sève en utilisant les dynamiques des ellipses.
Many biological surfaces in both the plant and animal kingdom possess unusual structural features at the micro- and nanometre-scale that control their interaction with water and hence wettability. An intriguing example is provided by desert beetles, which use micrometre-sized patterns of hydrophobic and hydrophilic regions on their backs to capture water from humid air. As anyone who has admired spider webs adorned with dew drops will appreciate, spider silk is also capable of efficiently collecting water from air. Here we show that the water-collecting ability of the capture silk of the cribellate spider Uloborus walckenaerius is the result of a unique fibre structure that forms after wetting, with the 'wet-rebuilt' fibres characterized by periodic spindle-knots made of random nanofibrils and separated by joints made of aligned nanofibrils. These structural features result in a surface energy gradient between the spindle-knots and the joints and also in a difference in Laplace pressure, with both factors acting together to achieve continuous condensation and directional collection of water drops around spindle-knots. Submillimetre-sized liquid drops have been driven by surface energy gradients or a difference in Laplace pressure, but until now neither force on its own has been used to overcome the larger hysteresis effects that make the movement of micrometre-sized drops more difficult. By tapping into both driving forces, spider silk achieves this task. Inspired by this finding, we designed artificial fibres that mimic the structural features of silk and exhibit its directional water-collecting ability.
Using kinematic and mechanical experiments, we have shown how fisher spiders, Dolomedes triton (Araneae, Pisauridae), can generate horizontal propulsive forces using their legs. This horizontal thrust is provided primarily by the drag of the leg and its associated dimple as both move across the water surface. Less important sources of resistance are surface tension and bow waves. The relative contributions of drag, surface tension and bow waves were examined in several different ways. In one experiment, we measured the forces acting on a leg segment as water flowed past it in non-turbulent flow; the bow wave was not present at leg relative velocities below 0.2ms-1 and thus cannot play a role in thrust production at low leg speeds. In a second experiment, we varied the surface tension by altering the concentration of ethanol from 0% to 9% in the experimental water tank. At a constant dimple depth, force varied little with changes in surface tension, a result consistent with the hypothesis that drag is the primary source of resistance. In addition, however, as surface tension decreased from 0.072 to 0.064Nm-1, the power exponent of the relationship between force and velocity (as measured by the exponent of the power function relating the two variables) increased; at lower surface tensions, down to 0.054Nm-1, the power exponent of the relationship between force and velocity decreased. These results suggest an influence of surface tension (albeit still secondary to drag) in generating horizontal resistance to leg movement. We also measured flow disturbance in the water downstream from a leg segment and confirmed that, even at velocities well below 0.2ms-1, the leg-cum-dimple transferred momentum to the water, which is a clear indication that drag is a contributor to the resistance encountered by a spider's leg. Finally, modeling the leg-cum-dimple as a circular cylinder generates values of drag that account for 7598% of the measured leg force when the dimple is 0 or 1mm deep. These results not only elucidate the primary mechanism of propulsion for D. triton and other similar-sized arthropods, such as adult water striders (Gerridae), but also suggest that the formerly enigmatic locomotion of very small water-walking organisms (e.g. first-instar water striders) can be understood in the same way.
Many nectar-feeding bird species decrease food intake when sugar concentration in food is increased. This feeding response can be explained by two alternative hypotheses: compensatory feeding and physiological constraint. The compensatory feeding hypothesis predicts that if birds vary intake to maintain a constant energy intake to match energy expenditures, then they should increase intake when expenditures are increased. Broad-tailed hummingbirds were presented with sucrose solutions at four concentrations (292, 584, 876, and 1,168 mmol L(-1)) and exposed to two environmental temperatures (10 degrees and 22 degrees C). Birds decreased volumetric food intake in response to sugar concentration. However, when they were exposed to a relatively sudden drop in environmental temperature and, hence, to an acute increase in thermoregulatory energy expenditures, they did not increase their rate of energy consumption and lost mass. These results support the existence of a physiological constraint on feeding intake. A simple chemical reactor model based on intestinal morphology and in vitro measurements of sucrose hydrolysis predicted observed intake rates closely. This model suggests that intestinal sucrose hydrolysis rates were near maximal and, thus, may have imposed limits to sugar assimilation. Although sugar assimilation was high (95%), the proportions of excreted sucrose, glucose, and fructose found in excreta differed significantly. The monosaccharides glucose and fructose were about eight and three times more abundant than sucrose, respectively. Broad-tailed hummingbirds are small high-altitude endotherms that face unpredictable weather and the energetic expense of premigratory fattening. Digestive processes have the potential to impose severe challenges to their energy budgets.
The transport system that drives sap ascent from soil to leaves is extraordinary and controversial. Like their animal counterparts, large multicellular plants need to supply all their cells with fuel and water.
We investigated why wet hair clumps into bundles by dunking a model brush of parallel elastic lamellae into a perfectly wetting liquid. As the brush is withdrawn, pairs of bundles aggregate successively, forming complex hierarchical patterns that depend on a balance between capillary forces and the elasticity of the lamellae. This capillary-driven self-assembly of flexible structures, which occurs in the tarsi of insects and in biomimetic adhesives but which can also damage micro-electromechanical structures or carbon nanotube 'carpets', represents a new type of coalescence process.
Water-walking insects and spiders rely on surface tension for static weight support and use a variety of means to propel themselves along the surface. To pass from the water surface to land, they must contend with the slippery slopes of the menisci that border the water's edge. The ability to climb menisci is a skill exploited by water-walking insects as they seek land in order to lay eggs or avoid predators; moreover, it was a necessary adaptation for their ancestors as they evolved from terrestrials to live exclusively on the water surface. Many millimetre-scale water-walking insects are unable to climb menisci using their traditional means of propulsion. Through a combined experimental and theoretical study, here we investigate the meniscus-climbing technique that such insects use. By assuming a fixed body posture, they deform the water surface in order to generate capillary forces: they thus propel themselves laterally without moving their appendages. We develop a theoretical model for this novel mode of propulsion and use it to rationalize the climbers' characteristic body postures and predict climbing trajectories consistent with those reported here and elsewhere.
The interaction between elasticity and capillarity is used to produce three
dimensional structures, through the wrapping of a liquid droplet by a planar
sheet. The final encapsulated 3D shape is controlled by tayloring the initial
geometry of the flat membrane. A 2D model shows the evolution of open sheets to
closed structures and predicts a critical length scale below which
encapsulation cannot occur, which is verified experimentally. This {\it
elastocapillary length} is found to depend on the thickness as , a
scaling favorable to miniaturization which suggests a new way of mass
production of 3D micro- or nano-scale objects.
Black-chinned Hummingbirds (Archilochus alexanderi) were offered combinations of sucrose and artificial sweeteners (saccharin, aspartame) at various concentrations and viscosity levels. Sucrose at 40% concentration was preferred over lower concentrations. Sucrose at 20% was preferred over artificial sweeteners, plain water, and low sucrose/high viscosity samples. Additions of artificial sweeteners to sucrose samples had no effect on nectar consumption and, therefore, were judged to be ineffective stimuli rather than aversive. Artificial increases in viscosity had no effects on the amount of nectar removed as long as a minimum of 15% sucrose was present. Hummingbirds responded to decreased sucrose concentrations by increasing sampling behavior at feeders; at increased sucrose levels, sampling behavior decreased. Chemosensory mechanisms rather than physical measures of viscosity are responsible for the sensory evaluation and the subsequent selection of sucrose nectars.
The development of a model simulating alternative hummingbird foraging strategies is described and predictions of the model are compared with foraging patterns recorded in the field. The hypotheses that: (1) natural foraging patterns more closely resembled systematic foraging than random foraging; and (2) systematic foragers were more efficient when resource distributions were clumped versus random were tested. Simulated foraging strategies included random, area-restricted, and directional foraging. The random strategy randomly selected the flowers a hummingbird visited. The area-restricted strategy allowed a hummingbird to visit any flower directly adjacent to the current flower, with an equal probability of visiting any adjacent flower. The directional strategy was based on the previous and current flowers visited, with a hummingbird following a straight path until it encountered an edge. At an edge, the hummingbird had an equal probability of turning and moving in any direction. A three-flower memory was incorporated into the strategies, so a simulated hummingbird could not revisit the last three flowers visited. During field trials and simulations, hummingbirds foraged in patches of 36 artificial flowers with uniform, clumped, and random nectar distributions. All the flowers in a uniform patch contained nectar. A clumped patch consisted of clumps of four rewarding flowers interspersed with clumps of four empty flowers. A random patch contained randomly distributed rewarding and empty flowers. Foraging efficiency for the field foraging patterns was measured and foraging strategies were simulated as microliters of nectar consumed per time step, assuming higher rates of consumption were more efficient than lower rates of consumption. In random patches, the field foraging patterns were more efficient than the simulated foraging strategies, whereas the field foraging patterns and area-restricted strategy were the most efficient in clumped patches. In the uniform patch, the directional strategy was the most efficient, followed by the field foraging patterns and random strategy. The random strategy was more efficient in patches with random versus clumped nectar distributions, whereas the area-restricted strategy was more efficient in clumped patches. No differences existed between clumped and random patches for the directional strategy or field foraging patterns. These results suggested the hummingbirds used different foraging rules in different patch types and incorporated information not included in the simulated strategies into their foraging patterns. This approach of replicating field experiments with a spatially explicit simulation model provides a valuable methodology for evaluating the effectiveness of different foraging strategies under different patterns of resource availability.
A survey of data from tropical and temperate regions confirms that nectars of hummingbird and honeyeater flowers are dilute, especially relative to nectars of bee flowers. These data are used, along with theoretical considerations, to examine three recently proposed hypotheses to explain low concentration of hummingbird nectars. None of the quantitative or qualitative predictions of these hypotheses appears to be upheld. -from Authors
Prediction on the deformation of a soft substrate induced by capillary force has been widely paid attention in the broad range of applications, such as metallurgy, material science, astronavigation, micro/nano-technology, etc., which is also a supplementary result to the classical Young's equation. We quantitatively analyzed the deformation of an elastic substrate under capillary force by means of the energy principle and the continuum mechanics method. The actual drop's morphology was investigated and was compared with that calculated based on the classical spherical shape assumption of the droplet. The displacement field of the substrate was obtained, especially, its singularity at the droplet edge was also discussed. The results are beneficial to engineering application and micro/nano-measurement.
Costa Rican hummingbirds and Australian honeyeaters respond to an increase in the volume of nectar made available in tubular flowers by increasing the duration of foraging bouts, the rate at which nectar is ingested, and the energetic efficiency of that process. Enhanced intake is the result of increased nectar capture by the tongue during each lick rather than of any significant change in licking rate. All species react to an increase in floral length by spending more time foraging and reducing nectar intake, short-billed species being most affected. Decreased nectar capture per lick, rather than a change in licking rate, is responsible for this response. Honeyeater foraging times increase and nectar-intake rates decrease when the curvature of flowers is increased, though all but one of the short-billed hummingbird species were relatively insensitive to this change. Hummingbirds harvest nectar with equal proficiency whether foraging at erect or at pendulous flowers, whereas the bouts of honeyeaters are longer, and their nectar-uptake rates lower, when they visit pendulous flowers. Overall nectar-extraction rates of hummingbirds, as measured in the laboratory, were greater than those of honeyeaters; values for both groups were generally higher than rates recorded in the field. Hummingbird and honeyeater tongues are equally adept at extracting nectar from tubular flowers, though my results suggest that honeyeater tongues would be more effective in situations where nectar is thinly and widely dispersed.
We present the results of a combined experimental and theoretical investigation of the motion of wetting droplets in tapered capillary tubes. We demonstrate that drops may move spontaneously towards the tapered end owing to the Laplace pressure gradient established along their length. The influence of gravity on this spontaneous motion is examined by studying drop motion along a tilted tube with its tapered end pointing upwards. Provided the tube taper varies, an equilibrium height may be achieved in which the capillary force is balanced by the drop's weight. We deduce the family of tube shapes that support a stable equilibrium.
Advantages of performing analytical and diagnostic tasks in microfluidic-based systems include small sample volume requirements, rapid transport times and the promise of compact, portable instrumentation. The application of such systems in home and point-of-care situations has been limited, however, because these devices typically require significant associated hardware to initiate and control fluid flow. Capillary-based pumping can address many of these deficiencies by taking advantage of surface tension to pull fluid through devices. The development of practical instrumentation however will rely upon the development of precision control schemes to complement capillary pumping. Here, we introduce a straightforward, robust approach that allows for reconfigurable fluid guidance through otherwise fixed capillary networks. This technique is based on the opening and closing of microfluidic channels cast in a flexible elastomer via automated or even manual mechanical actuation. This straightforward approach can completely and precisely control flows such as samples of complex fluids, including whole blood, at very high resolutions according to real-time user feedback. These results demonstrate the suitability of this technique for portable, microfluidic instruments in laboratory, field or clinical diagnostic applications.
Microfluidic systems are part of an emerging technology which deals with minute amounts of liquids (biological samples and reagents) on a small scale. They are fast, compact and can be made into a highly integrated system to deliver sample purification, separation, reaction, immobilization, labelling, as well as detection, thus are promising for applications such as lab-on-a-chip and handheld healthcare devices. Miniaturized micropumps typically consist of a moving-part component, such as a membrane structure, to deliver liquids, and are often unreliable, complicated in structure and difficult to be integrated with other control electronics circuits. The trend of new-generation micropumps is moving-part-free micropumps operated by advanced techniques, such as electrokinetic force, surface tension/energy, acoustic waves. This paper reviews the development and advances of relevant technologies, and introduces electrowetting-on-dielectrics and acoustic wave-based microfluidics. The programmable electrowetting micropump has been realized to dispense and manipulate droplets in 2D with up to 1000 addressable electrodes and electronics built underneath. The acoustic wave-based microfluidics can be used not only for pumping, mixing and droplet generation but also for biosensors, suitable for single-mechanism-based lab-on-a-chip applications.
The tongues of Australian honeyeaters (Meliphagidae) are broader and more fimbricated at the top than the bifurcated tongues of sunbirds (Nectariniidae) and hummingbirds (Trochilidae); the bills of hummingbirds are more uniformly narrow and taper less markedly towards their tips than those of sunbirds and honeyeaters; and bill curvatures are generally greater for sunbirds and honeycreepers than for hummingbirds. A variety of hummingbirds has straight or even slightly upturned bills; bills for all sunbirds, honeycreepers and honeyeaters are decurved to some extent. Hummingbirds, sunbirds and honeyeaters extract nectar at a similar range of rates, averaging c40 μL s-1 from feeders, and 1-15 μL s-1 from flowers. All tongues collect nectar by capillarity, with licking rates of 6-17 s-1. Bill lengths of nectarivorous birds are similar in all regions, though species of hummingbird have the shortest and longest bills. Rates of nectar extraction decline rapidly once the floral length exceeds bill length. Decurved bills may have evolved in honeyeaters and sunbirds to enable perching birds to reach flowers at the ends of branches more easily. Consistent differences in bill length between the sexes suggest that males and females may exploit different floral resources or different proportions of the same resources. For honeyeaters and sunbirds, males have longer bills than females, but the reverse is true for many hummingbirds. -from Authors
Surface tension prey transport is a feeding mechanism employing the surface tension of water surrounding prey to transport prey from bill tip to mouth. Previously, it has been demonstrated only in the Red-necked Phalarope Phalaropus lobatus. On the basis of a model of the bill morphology necessary for this method of prey transport, I suggest that many species of shorebird should be capable of surface tension feeding. Laboratory investigations of the feeding mechanics of Wilson's Phalarope Phalaropus tricolor, Western Sandpiper Calidris mauri and Least Sandpiper Calidris minutilla demonstrated that all three use surface tension transport of prey when feeding in water. I examined interspecific variation in the performance of this feeding mechanism with a high-speed video system and a customized motion analysis system. Exploratory analyses indicated significant interspecific variation in distance the prey is transported per cycle of mandibular spreading, gape increase per unit transport, speed of transport, total number of cycles necessary to complete transport and total time to complete transport. The calidrid sandpipers also occasionally used other feeding mechanisms in conjunction with surface tension transport of prey. The discovery that these sandpipers, which normally obtain prey by probing, are capable of surface tension transport of prey implies that the capacity to employ this feeding mechanism may be widespread in the Scolopacidae and may have been a significant factor in the evolutionary radiation of phalaropes into aquatic environments.
Superhydrophobic surfaces were obtained using a simple, cost-effective, and novel method on a biodegradable polymer. Different times of Ar-plasma treatment were used to increase the hydrophilicity of the samples and achieve controlled water contact angle (CAs) down to the superhydrophilic regime. A flat rigid poly(L-lactic acid) PLLA substrate was obtained by melting of PLLA powder over a glass slide, compression with another glass slide, and further cooling in water. During the evaporation period, partial dissolution into the interface of the rigid substrate occurs. During the phase separation of the solution, crystallization of PLLA takes place, resulting in solid liquid demixing accompanying the liquid liquid demixing. It is clear that besides the roughness at the micrometer level, the individual papilla-like structures exhibit a clear rough texture at the nanometer level. The results suggest that for the surfaces treated with Ar plasma for 50 s, the combination of roughness, surface chemistry, and wettability present the best environment for the cells.
To explore the mechanical determinants of feeding strategies for nectar feeders, we develop a fluid dynamical and behavioral model describing the mechanics and energetics of capillary feeding in hummingbirds. Behavioral and morphological data for Calypte and Archilochus are used to test and illustrate this model. We emphasize the important differences between capillary and suction mechanisms of fluid feeding. Model predictions of nectar intake rates and nectar volumes per lick are consistent with observed values for Calypte anna. The optimal nectar concentration maximizing rate of energy intake depends on tongue morphology and licking behavior. For hummingbirds exhibiting optimal licking behavior, the optimal nectar concentration is 35–40% sucrose for feeding on large nectar volumes. For small nectar volumes, the optimal concentration is 20–25%. The model also identifies certain tongue morphologies and licking frequencies maximizing energy intake, that are consistent with available observations on licking behavior and tongue design in nectar feeding birds. These predictions differ qualitatively from previous results for suction feeding in butterflies.
The model predicts that there is a critical food canal radius above which suction feeding is superior to capillary feeding in maximizing the rate of energy intake; the tongues of most hummingbirds and sunbirds fall above this critical radius. The development of suction feeding by nectarivorous birds may be constrained by the elastic properties of their flexible tongues. Our results show that, in terms of morphology, scaling, and energetics, different mechanisms of feeding on the same food resource can lead to qualitatively different predictions about optimal design and feeding strategies.
In a series of daul choice tests with large volume feeders, rufous hummingbirds preferred sucrose concentrations near those that maximized their instantaneous rates of energy intake. As predicted on theoretical grounds, energy intake rates increased with increasing sucrose concentration to a maximum then decreased above this maximum. Earlier experimental studies suggested that hummingbirds always prefer the highest available concentration. Our results are consistent with the data of these studies, but by using a wider range of concentrations than previous workers, we found that the hummingbirds discriminated against very concentrated solutions.
Handling times of hummingbirds (Amazilia rutila and Cynanthus latirostris) visiting artificial flowers were a positive function of corolla length, nectar volume and nectar concentration. Corolla angle had no consistent effects on handling times. A multiple regression model explained 83% of the variation in handling times for these two species. The model also closely fit independent data from another hummingbird, Archilochus colubris, suggesting that it is general enough to apply to other medium-sized, short-billed hummingbird species. When examined across the range of variation normally encountered by hummingbirds in nature, corolla length and nectar volume had the largest effect on nectar extraction rates. At corolla lengths longer than a hummingbird's bill handling time increases markedly. Hummingbirds maximize their net rate of energy intake by selecting flowers with the shortest corolla, the highest nectar concentrations and the highest nectar volume. Since there is a positive relation between bill length and nectar extraction rate, it is surprising that most hummingbirds have relatively short bills.
A model is developed to elucidate the determinants of sugar concentrations in flower nectars. This model analyses the efficiency of sugar intake, or energy flux, which for nectarivores closely approximates the rate of net energy gain. For both steady state and some non-steady flows of nectars, this energy flux is shown to be maximal at particular sugar concentrations referred to here as the maximum flux concentration. Higher concentrations actually yield lower energy intake rates because the concomitant rapid increase in viscosity sharply reduces the rate of fluid intake. For pure sucrose solutions, the maximum flux concentration is 22%. For flower nectars, which are chemically more complex, the maximum flux concentration is predicted to be closer to 26%, using the first viscosity measures obtained for flower nectars. This concentration is shown to be essentially independent of the pollinator's feeding organ morphology and of the type of potential inducing nectar flow. It is proposed that this concentration applies for virtually all pollinators that select nectars with maximal energy flux.
However not all pollinators are expected to select such nectars because this 26% concentration is not necessarily “optimal”. The model predicts that optimal sugar concentrations vary for particular pollinators as a function of two primary factors: (1) the energy flux derived from the nectar, as discussed above, as well as (2) the relative contribution of transit costs to overall foraging costs. Relatively “dilute” nectars, with sugar concentrations close to the maximal flux value, are predicted for flowers pollinated by organisms that minimize feeding time to reduce high feeding costs, such as that of hovering or of exposure to enhanced predation while feeding. More concentrated nectars are predicted for flowers pollinated by nectarivores that incur high foraging transit costs relative to feeding costs.
Flowers pollinated by hovering pollinators, including many hummingbirds, hawkmoths and bats, have nectars with mean sugar concentrations in close accord with the 26% maximum flux concentration predicted. Moreover, these nectars have relatively low concentrations of nonsugar constituents, which increase viscosity and thereby decrease sugar flux. Over 75% of the flowers examined in this study, which are pollinated primarily by territorial hummingbird species, provide nectars that allow sugar uptake with an efficiency of 90% or greater of the maximal value. According to the model, these data suggest that feeding costs of these pollinators far outweigh foraging transit costs. In contrast, the model suggests that flower nectars taken by traplining hummingbirds and by bees, with sugar concentrations significantly above the maximum flux value, reflect the higher costs of foraging flight relative to costs of feeding for these pollinators.
Increasing temperature decreases nectar viscosity, and thereby increases absolute nectar uptake rates sharply. This leads to a number of predictions regarding foraging behavior as well as flower location, orientation, and color. However, the maximum flux concentration is shown to be practically invariable over a wide range of temperatures-increasing by only 2% sugar from 10°C to 30°C. Thus, contrary to previous expectations, little change in average sugar concentrations of flowers pollinated by particular groups of nectarivores is expected from cooler to warmer regions.
Fabrication of 3D electronic structures in the micrometer-to-millimeter range is extremely challenging due to the inherently 2D nature of most conventional wafer-based fabrication methods. Self-assembly, and the related method of self-folding of planar patterned membranes, provide a promising means to solve this problem. Here, we investigate self-assembly processes driven by wetting interactions to shape the contour of a functional, nonplanar photovoltaic (PV) device. A mechanics model based on the theory of thin plates is developed to identify the critical conditions for self-folding of different 2D geometrical shapes. This strategy is demonstrated for specifically designed millimeter-scale silicon objects, which are self-assembled into spherical, and other 3D shapes and integrated into fully functional light-trapping PV devices. The resulting 3D devices offer a promising way to efficiently harvest solar energy in thin cells using concentrator microarrays that function without active light tracking systems.
We modeled hummingbird visits to flowers on three temporal scales: tongue loading, the licking cycle, and entire visits to flowers. The nectar concentration that maximizes energy intake rate increases with the temporal scale of integration; therefore, optimal nectar concentration for nectar volumes that require many licks is higher than predicted by models that assume single licks. Since birds must position, insert, and withdraw their bills in addition to licking nectar, the optimum at the scale of flower visits is even higher. This "overhead time cost" of handling flower morphology, for most nontraplining hummingbirds under most natural conditions, is as great as or greater than the cost of handling nectar. For these birds, the potential variation in the fine-scale factors that determine nectar intake rate during licking has little effect on flower-handling time and therefore is unlikely to determine optimal nectar concentration or the profitability of visiting flowers. The conclusion that energy intake rate and optimal nectar concentration are sensitive to temporal scale of integration applies at all scales in hummingbird foraging systems, and we suggest that it also generalizes across systems.
Hummingbirds are among the smallest endothermic vertebrates. Because they forage by energetically costly hovering, and because weight-specific basal metabolic rates increase with decreasing body size, their basal and active metabolic rates are among the highest recorded. Hummingbirds fuel these metabolic requirements mainly with highly concentrated sugar in nectar, which they extract rapidly and efficiently by an unknown mechanism. It is especially puzzling that, despite their high energy requirements, hummingbirds spend only approximately 20% of their waking hours feeding, but 75% perched and apparently doing nothing. Here we report the first measurement of nutrient absorption by hummingbird intestine and present a new method for measuring crop-emptying times. We find that hummingbird intestine has the highest active glucose transport rate and lowest passive glucose permeability reported for any vertebrate. Crop-emptying time may limit feeding-bout frequency and could largely account for the time spent perched.
1.1. Rate of intake of hummingbirds (3·1 and 7·9 g) visiting a feeder was greater for larger hummingbirds but was not dependent on sugar concentration up to 1 ·0 molar sucrose.2.2. Most flowers produce nectarwith concentrations (0·24-1·48 molar sucrose) that should not influence rate of nectar intake.3.3. Rate of tongue licking was independent of body size (2·6-3·8 licks/sec), but the larger hununingbird obtained more nectar per tongue lick.4.4. Morphological studies indicated that the grooves on the tongues of hummingbirds may play a minor role in determining rate of nectar intake at a feeder with large nectar volumes, but they could be important in emptying small nectar volumes from flowers.5.5. Adding a “corolla” to the feeder resulted in a linear decrease in rate of intake with increasing “corolla” length. However, corolla curvature, position and the volume of nectar in flowers are also important for determining rate of nectar extraction from flowers.
Some beetles in the Namib Desert collect drinking water from fog-laden wind on their backs. We show here that these large droplets form by virtue of the insect's bumpy surface, which consists of alternating hydrophobic, wax-coated and hydrophilic, non-waxy regions. The design of this fog-collecting structure can be reproduced cheaply on a commercial scale and may find application in water-trapping tent and building coverings, for example, or in water condensers and engines.
In the 19th century, Oscar Wilde stated "We live, I regret to say, in an age of surfaces". Today, we do so even more, and we do not regret it: key advances in the understanding and fabrication of surfaces with controlled wetting properties are about to make the dream of a contamination-free (or 'no-clean') surface come true. Two routes to self-cleaning are emerging, which work by the removal of dirt by either film or droplet flow. Although a detailed understanding of the mechanisms underlying the behaviour of liquids on such surfaces is still a basic research topic, the first commercial products in the household-commodity sector and for applications in biotechnology are coming within reach of the marketplace. This progress report describes the current status of understanding of the underlying mechanisms, the concepts for making such surfaces, and some of their first applications.
A core assumption implicit in economic models of animal choice is that subjects assign absolute utilities to options that are independent of the type and number of alternatives available. Humans sometimes appear to violate this assumption and employ relative, as opposed to absolute, currencies when making choices. Recent evidence suggests that animals too might sometimes employ relative choice mechanisms. We tested this idea by measuring the foraging preferences of rufous hummingbirds (Selasphorus rufus) faced with choices analogous to those in which human use of relative currencies is evident. The birds experienced three treatments: a binary choice between two artificial flower types designated concentration (20 microl, 40% sucrose solution) and volume (40 microl, 20%), and two trinary treatments in which a third decoy option (either concentration decoy: 10 microl, 30% or volume decoy: 30 microl, 10%) was added to the set. The birds' preferences differed significantly across the three treatments. In the trinary treatments, the effect of the decoy options was to increase the preference for the option that dominated the decoy. These results are similar to those reported in the human choice literature, and are compatible with the hummingbirds using a relative evaluation mechanism in decision making.
The development of a micromachined fluidic structure for the introduction of liquid samples into a chip-based sensor array composed of individually addressable polymeric microbeads is presented. The micromachined structure consists of micromachined storage cavities combined with a covering glass layer that confines the microbeads and fluidic channels. In our sensor array transduction occurs via optical (colorimetric and fluorescence) changes to receptors and indicator molecules that are covalently attached to termination sites on the polymeric microbeads. Spectral data are acquired for each of the individual microbeads using a charged-coupled device (CCD) allowing for the near-real-time analysis of liquid sample. Hence the micromachined fluidic structure must allow for both optical access to the microbeads and fluid flow through the micromachined cavities that serve as the microreactors/analysis chambers. One of the key parts of the structure is a passive fluid introduction system driven only by capillary force. This simple means of fluid introduction realizes a compact device. The capillary flow on the inlet channel has been studied, and the responses of the microbeads (alizarin complexone) to a liquid sample have been characterized. The test results show that this system is useful in a micro-total-analysis-system (mu-TAS) and biomedical applications.
The Naturalist's Library: A General History of Humming-Birds or the Trochilidae
- Wcl Martin
Martin WCL (1833) The Naturalist's Library: A General History of Humming-Birds or the
Trochilidae, ed W Jardine (H.G. Bohn, London), Vol 41, pp 65-68.