No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Notes on the breeding behavior of the Bumblebee Hummingbird (Atthis heloisa), an endemic species of Mexico: Nest, courtship displays, and altitudinal movements
Abstract and Figures
The Bumblebee Hummingbird (Atthis heloisa) is an endemic bird to Mexico. Its natural history is poorly known, particularly its breeding biology. We provide novel and complementary information that enriches the biological knowledge on the species. We describe a nest of the Bumblebee Hummingbird found in Northern Oaxaca and
characterize the nest site. The nest was mainly assembled with mosses and lichens; however, we recorded females transporting hairs of the invasive fern Pteridium sp. and seeds of the bromeliad Catopsis sp. for nest construction. Males were noisy and conspicuous while females were secretive; thus, we suggest considering differences in
detectability among sexes when studying the species. Males exhibited courtship displays that consisted of several vertical movements over females while adopting a horizontal posture, erecting the tail, emitting a bee-like sound, and fanning out the feathers of the throat toward the females. The Bumblebee Hummingbird is considered a sedentary species, but we suspect it performs altitudinal movements in search of cloud forests during spring and summer and humid pine-oak forests during winter and autumn. Although the literature indicates that this hummingbird reaches breeding conditions between April and July, we recorded intense breeding activity only during January and February. It is not clear if such variation is regional or if the species could breed multiple times during the year.
Figures - uploaded by Rubén Ortega-Álvarez
Author content
All figure content in this area was uploaded by Rubén Ortega-Álvarez
Content may be subject to copyright.
... However, we observed that urban-cropfield areas favored feeding of nectarivores during summer. During this season, most hummingbirds do not breed (Binford, 1989;Ortega-Álvarez et al., 2018b), so they do not depend on nesting sites and materials exclusively provided by forests. Instead, this group of birds appears to have adjusted in this region to exploit the surplus of feeding resources provided by urban settlements (e.g. ...
(https://authors.elsevier.com/c/1cr80cUG5L3~v)
<<Use the previous link for free download before May 22, 2021>>
Evaluating the impact of anthropogenic habitats on wildlife has been a major topic of research and conservation concern. However, most knowledge relies on incidence data, masking some of the effects that human land uses have on animal behavior. We explored the use of avian behaviors for measuring the impact of an indigenous working landscape on biodiversity. Specifically, we examined how land uses (i.e. conservation forests, selective forestry management plots, forests sanitation areas, urban-cropfield sites) in a Neotropical working landscape affect bird behaviors (i.e. feeding, perching, preening, fighting, breeding). We estimated and compared the proportion of times that we recorded birds performing each behavior across land uses, seasons, and avian groups. Moreover, we estimated species richness for our focal bird assemblages and land uses, which we compared with the behavioral patterns. Results revealed that species richness and behaviors provide different pieces of information. According to our estimates of species richness, urban-cropfield areas harbored the greatest number of species during both winter and summer for most of the avian groups, including forest birds. However, behavioral analyses showed that forestry plots are particularly important for resident forest birds, frugivores, and insectivores since these bird groups exhibited high frequencies of feeding, perching, and breeding behaviors at these sites. Urban-cropfield specialists and migrants showed low frequencies of behaviors in all forested sites. Urban-cropfield areas benefited granivores and nectarivores, a pattern that was likely driven by increased availability of grains and nectar. Our results support the use of behavior for evaluating the impact of anthropogenic habitats on animals, identifying supplementary habitats for wildlife, and assessing the sustainability of working landscapes.
Los monitores comunitarios (MC) participan de forma estratégica en proyectos de investigación como actores no científicos, por pertenecer a comunidades locales del área de estudio y conocer su biodiversidad; sin embargo, existe poca información respecto a su impacto, quehacer y contribución. El objetivo del presente trabajo fue determinar la colaboración de los MC en tres áreas naturales protegidas (ANP) de México (Tamaulipas y Veracruz). Mediante entrevistas semi-estructuradas se estableció el tipo de interacciones existentes entre los MC, investigadores responsables de proyectos, miembros de entidades públicas que otorgan financiamiento y el representante de una organización no gubernamental. Se revisaron 31 reportes finales de 15 investigadores que trabajaron con MC para corroborar el registro de la contribución. Su actividad se registró desde 2002, principalmente en monitoreo de aves (35.48 %), recolectando muestras, datos, información y recursos, ayudando a interpretar resultados y extraer conclusiones. Los beneficios percibidos de su participación
como MC los reflejaron en el ámbito personal, local, institucional y de conservación. Los proyectos fueron su principal fuente de aprendizaje, otorgándoles experiencia, capacitación y conocimientos, que les permitió incorporarse a nuevos proyectos y mejorar su trabajo como guías de turistas, su otra fuente de ingresos. Manifestaron falta de valoración y certificación de sus conocimientos como MC, limitando su desarrollo y situación económica. Se localizaron 12 productos académicos, que incluían
a 2 MC como autores, y que fueron generados por 2 investigadores de los 15 que participaron en este estudio, lo que indica su exclusión y falta de reconocimiento. Se requieren acciones que permitan certificar su conocimiento como MC, para facilitar su desarrollo y mejorar su situación económica. Esto evitaría poner en riesgo su contribución, de vasta experiencia empírica-técnica que ha obtenido con su labor a lo largo del tiempo.
The loss of interactions and ecosystem functions is a concerning by‐product of pervasive Anthropocene species decline and extinction. Ecological interactions between species sustain the provision of ecosystem processes, especially those mediated by trophic relationships such as pollination and predation. At the local habitat scale, the diversity of natural food sources may increase the diversity of interactions, thus enhancing the stability of local communities and ecosystem functioning. Here I discuss the importance of bromeliads as a potential provider of additional trophic interactions with birds, a key animal group in the Neotropics. Based on 88 studies published between 1965 and 2020 across the Neotropical region, I observed that bromeliads act as ‘wildlife restaurants’ by providing an additional food source throughout the year in almost all Neotropical ecosystems for at least 162 bird species (mostly hummingbirds). These plants (both epiphytic and terrestrial forms) can provide nectar, flowers, water for drinking, invertebrates, small vertebrates, seeds, and fruits, as well as nest materials and substrates. Given these trophic relationships between bromeliads and birds, actions to restore the richness and abundance of these plants in changed habitats would potentially enhance the local diversity of birds. I discuss and recommend the use of bromeliad transplantations as a relevant conservation tool for birds and some implications for the maintenance of species and interaction diversity in natural and agricultural habitats.
Assessing the impact of working landscapes on biodiversity and defining locally contextualized management guidelines for productive activities are key for sustainability. Occupancy dynamics provide information about sites in the landscape that are either avoided or preferred by populations through the estimation of extinction and colonization probabilities, respectively. We identified the habitat traits that affected colonization and extinction probabilities of target birds (forest‐dependent, endemic, or conservation concern species) within a Neotropical working landscape by using multi‐season occupancy models to point count data collected through a participatory monitoring approach and considering our imperfect detectability of species in the field. We provided colonization and extinction scenarios according to local land uses (forestry plots, urban‐cropfield areas, and conservation forests) to recommend management activities that could have a positive impact on bird conservation. Shrub cover was key for local colonization of most of our focal species. Increasing values of tree size and tree species richness can enhance microhabitat complexity, which in turn promotes the presence of arboreal birds. Selective forestry management, in which only the largest individuals of a few tree species are extracted, promoted high colonization rates of birds because the structure of the vegetation remains relatively unaffected. In contrast, intensive forestry management plots, in which most trees are removed, resulted detrimental for bird occupancy. Local management guidelines should pay special attention to maintaining shrub cover, tree size, and tree species richness above critical values (>50%, >30 cm, >7 tree species, respectively) to promote habitat use by birds in this type of working landscapes.
Abstract in Spanish is available with online material.
We report the finding of a White-eared Hummingbird (Basilinna leucotis) nest during the winter. The observation took place on 9 February 2019 in San José del Pacífico, Oaxaca, Mexico, in the Sierra Madre del Sur. The hummingbird nest was located in the understory, 115 cm above the ground. The nest was placed within a plot of a pine-oak forest at 2,857 m a.s.l. and had 2 nestlings with complete juvenile plumage. Floral phenology is known to be a key factor that determines the biological cycles of hummingbirds, which rely heavily on nectar resources to fulfill their nutritional needs in the breeding season. Around the nest, we observed Salvia punicans Epling, a plant that blossoms during the winter months in the Mexican mountains and is visited by White-eared Hummingbirds. Previous winter nest records in Southern Oaxaca date from more than 50 year ago. We briefly discuss the implications of winter reproduction for the species and the potential commonness of this event.
Aim
Understanding patterns of endemism is a key to deciphering the history of biotas and setting conservation priorities, but resolving the complexity of distributional patterns quantitatively into areas of endemism is often a difficult task. We report here an analysis of a comprehensive biodiversity dataset for the study of endemism, including virtually all vouchered records available for resident land birds of Mexico (> 100,000 georeferenced data points for all 780 species).
Location
Mexico.
Methods
The dataset was analysed with methods that recover areas without assuming prior endemic status for any species. This grid‐based method for detecting areas of endemism considers co‐occurrence and exclusiveness of species in alternative sets of geographic cells at different spatial resolutions, and finds optimal sets using heuristic, computationally intensive searches.
Results
We provide the most detailed study of endemism in Mexico to date. Our analysis recovered 17 of 18 previously recognized areas of endemism for Mexican birds, plus many additional areas clearly supported by distributional data totalling 33 areas of endemism at different spatial scales. These areas cover 70% of the country's surface and form a network of nested and partially overlapping regions, some of which are also disjoint.
Main conclusions
This picture contrasts strongly with previous conceptions of areas of endemism as non‐overlapping and spatially simple in terms of scale. Our results reveal that endemism may be spatially complex and shed new light on its role as a key manifestation of biodiversity. Species identified as endemic to these areas comprise > 30% of the land birds of Mexico, with a disproportionately large fraction endangered according to IUCN or SEMARNAT .
We describe the relative abundance, plant species visited, and plant communities used by hummingbird species inhabiting the Tehuacán- Cuicatlán Biosphere Reserve, a semiarid area in South-central Mexico. We recorded 14 hummingbird species and 35 plant species distributed in 4 plant communities during our study. We found 86 different hummingbird-plant interactions. Amazilia violiceps and Cynanthus latirostris were the most common hummingbirds, while C. latirostris, A. violiceps, and Cynanthus sordidus were the hummingbirds that visited more plant species. Hummingbirds were distributed differentially between plant communities inside the reserve, with 12 species being present in the arboreal plant community of the lowlands, 11 both in cactus forest and perennial spine shrub plants, and 6 in perennial unarmed shrub plants. Cercidium praecox (Fabaceae) was the plant species with the highest number of visiting hummingbird species (10 species). Cactus forest and perennial spine shrub plants were the plant communities with largest number of possible interactions (57 and 51, respectively). The mean connectance value of the interaction matrix was similar between plant communities (near to 22%), but lower than those reported previously in other places. In the Tehuacán-Cuicatlán Biosphere Reserve the hummingbird-plant interaction system will be preserved if the hummingbirds C. latirostris, A. violiceps, C. sordidus, and L. clemenciae, and the plants C. praecox, I. arborescens, E. chiotilla, and TV. glauca, are protected.
Theory predicts low niche differentiation between species over evolutionary time scales, but little empirical evidence is available. Reciprocal geographic predictions based on ecological niche models of sister taxon pairs of birds, mammals, and butterflies in southern Mexico indicate niche conservatism over several million years of independent evolution (between putative sister taxon pairs) but little conservatism at the level of families. Niche conservatism over such time scales indicates that speciation takes place in geographic, not ecological, dimensions and that ecological differences evolve later.
1. Flower nectar robbers which extract flower rewards to pollinators but do not pollinate, may reduce the fitness of the plant. In this study we combined field observations and experimental manipulations to assess the role of a primary nectar robber, the bird Diglossa baritula, on flower nectar secretion and reproductive output of two hummingbird-pollinated plant species with contrasting breeding systems. We used the hermaphroditic Salvia mexicana and the androdioecious Fuchsia microphylla. In addition, because the distinction between pollinators and robbers is not so sharp, we compared the pollination efficiencies of D. baritula and of five species of humming-birds visiting the flowers of the same plant species. 2. Flowers of the two plant species were frequently robbed (92 and 37% of the flowers in Salvia mexicana and Fuchsia microphylla respectively). For both species, field censuses of robbed and unrobbed flowers showed no differences in fruit set. Experimentally induced nectar robbery did not affect the cumulative production of nectar in both plant species. However, in S. mexicana, but not in F. microphylla, intact flowers produced more concentrated nectar. 3. The role of D. baritula and hummingbirds on seed production per flower, was assessed by exposing individual flowers to different schedules of visitation by caged flower visitors. In S. mexicana, the number of seeds produced by flowers visited by the robber only was similar to that of flowers visited by the least efficient pollinator but lower than that of those visited by the other pollinators. 4. In F. microphylla, seed production by flowers visited by the robber only was lower than that of flowers visited by all other pollinators. 5. For both plant species visitation by the robber plus hummingbirds yielded a similar number of seeds as flowers visited by the more effective pollinator. 6. There was no field evidence that nectar robbery by D. baritula damages nectaries or ovules and, since under natural conditions flower visitation by the robber only was very rare, we conclude that for these two plant species D. baritula may be regarded as a commensal or even a low-efficiency pollinator.
Acknowledgments: The late L. Richard Mewaldt was the first among,equals in setting high standards and maintenance of accurate records. His contributions are detailed by Ralph (1992). We take great pleasure in dedicating this handbook,to him. This handbook,is a direct outgrowth,of the landbird program,started more than 25 years ago at the Point Reyes Bird Observatory to monitor landbird populations in coastal California, and much of this handbook is the result of the methods developed and adapted there. Over this period, many people contributed to the development,of this landbird monitoring program. The handbook benefitted greatly from discussions and correspondence by Bruce Bingham, Grant Ballard, Danny Bystrak, Barbara Carlson, Brenda Dale, Sam Droege, John Faaborg, Kevin J. Gutzwiller, Denise Hardesty, Kimberly Hollinger, Bill Howe, David W. Johnston, Stephanie Jones, Cherry Keller, Kathy Klimkiewicz, Rolf R. Koford, Karin Kozie, Borja Milá, Sherri Miller, Michael Morrison, Barry
Spatial distribution of resources is known to govern animal distribution and behaviour. However, few
empirical studies have formally evaluated this relationship. Unlike previous studies in which a patch or gap of floral resources is defined a priori by the observer at a subjective perception scale, we used the Spatial Analysis by Distance IndicEs (SADIE) to assess the location, length and spatial co-occurrence of patches and gaps of Palicourea padifolia inflorescences and hummingbird activity (feeding, perching, vocalizing, flying past and agonistic behaviour) in a tropicalmontane cloud forest of central Veracruz,Mexico. Along a 1010-m transect, both resource and hummingbird activity had a distribution approximately200%moreaggregated than expected by chance, at a scale of tens to hundreds of metres in length. In addition, aggregation patterns of resource and overall and agonistic hummingbird activity were found to be positively associated in 2009 but negatively in 2010. Campylopterus curvipennis and Amazilia cyanocephala were the most frequent species involved in vocal and agonistic activity. The difference observed between the two years may be due to changes in the composition and dominance of hummingbird species with different foraging strategies. In both years, hummingbird overall activity was positively correlated to size of resource patches.
Nectar robbers are animals that extract the nectar produced by plants without effecting pollination. These animals can have negative, positive, or neutral effects on the interaction, depending on the direct and indirect effects of each participant in the system. The purpose of this work was to analyze the prevalence of nectar robbing and its temporal dynamics in a tropical highland forest in western Mexico. The system was studied in terms of the seasonal changes in (i) specific composition and abundance of hummingbird pollinators, their hosts, and the nectar robbers, (ii) use of resources by the nectarivorous birds and flowers, and (iii) prevalence of flower piercing by the cinnamon flowerpiercer, Diglossa baritula. The guild consisted of 17 species of hummingbirds, 2 species of nectar robbers, and 21 plant species that were visited by nectarivorous birds (robbers and pollinators). The relative abundance of birds and available flowers showed two peaks, one in winter and the other in the rainy season. Some plant species were used more than expected from their abundance. Overlap in the use of flowers among hummingbirds and also between hummingbirds and the nectar robbers was high. Nectar robbing was found to be widespread, occurring in almost all of the plants known to be hummingbird pollinated. The ratio of hummingbirds to nectar robbers was around 10 throughout the year.
A honeydew-producing scale insect, Stigmacoccus garmilleri (Margarodidae), is associated with oak trees (Quercus spp.) in highland forests of Mexico. Although feeding by ants on scale-insect honeydew is more frequently documented in the literature, the honeydew produced by feeding instars of S. garmilleri is sufficient to provide nourishment for birds. This study elucidates bird use of honeydew in the tropical montane forests near Chiconquiaco, Veracruz, Mexico, and uncovers patterns in honeydew foraging. Over a 2-mo period, 40 trees harbouring scale insects, located in both forest and pasture areas, were intensely studied (160 h of bird-foraging observations along with quantitative measurements of honeydew production). Fifteen resident bird species and 18 migrant species were observed visiting observation trees. Approximately 72% of the resident bird species and 83% of the migrant bird species observed were recorded to forage on scale-insect honeydew. Audubon's warbler (Dendroica coronata auduboni) was the most active consumer and defender of the resource. Of 118 aggressive chases observed, only 9.65% occurred in forest observation trees, and 90.3% in pasture trees. Audubon's warbler demonstrated preferential defence and territorial patrolling of scale-insect honeydew in scattered pasture trees.
The adaptiveness of distyly has been typically investigated in terms of its female function, specifically pollen receipt. However, pollen loads on stigmas can only provide moderate support for Darwin's hypothesis of the promotion of legitimate crosses. To determine the effectiveness of hummingbirds as pollen vectors between floral morphs and the consequences in terms of male (pollen transfer) and female function (pollen receipt) in Palicourea padifolia (Rubiaceae), floral visitors, their foraging modes, and temporal patterns of floral visitation were observed and documented. Differences in pollen and stigma morphology, pollen flow, rates of pollen deposition, and/or stigmatic pollen loads were then evaluated for their contribution toward differences in reproductive output between floral morphs. A pollination experiment with stuffed hummingbirds that varied in bill size was done to evaluate the contribution of bill variation toward differences between floral morphs in pollen receipt and pollen transfer and female reproductive output. Anthers of long-styled flowers contained significantly more and smaller pollen grains than those of short-styled flowers, independently of corolla and anther lengths. The shape and orientation of the stigma lobes differed between morphs and were significantly longer among short-styled flowers. Hummingbird visitation rates did not differ significantly between floral morphs, and foraging movements from focal plants towards neighboring plants were independent of floral morph. Stigmatic pollen loads under field conditions and those after controlled hummingbird visitation, along with rates of pollen accumulation through the day indicated that stigmas of short-styled flowers receive proportionately more legitimate (intermorph) pollen grains than did those of long-styled flowers. However, the species of hummingbird was marginally significant in explaining variation in pollen deposition on stigmas. Lastly, intermorph pollinations of P. padifolia resulted in significant differences in fruit production between floral morphs, independent of pollination treatment and pollinator species; short-styled flowers proportionately developed almost twice the number of fruits developed by long-styled flowers.
Spatial and temporal variation in interactions between hummingbirds and plants have often been examined, and hummingbirds and insects are known to indirectly interact in networks of nectar plants. In a highland temperate forest in Hidalgo, Mexico some oak trees were heavily infested by honeydew-producing insects (family Margarodidae, tribe Xylococcini, genus Strigmacoccus) and the honeydew was consumed by hummingbirds. Here using survival analysis we investigate how the honeydew produced by dense populations of these margarodids is temporally and spatially partitioned by hummingbirds. We also measured the availability and quality of honeydew exudates, and then we recorded the time until a bird visited and used such resources. Four hummingbird species consumed this resource (Atthis eloisa, Hylocharis leucotis, Colibri thalassinus and Eugenes fulgens). Data from 294 hours of observation on seven focal trees suggested temporal and spatial segregation among visiting birds according to body size and territorial behavior during the most honeydew-limited time. Hummingbird species differed in the daily times they foraged, as well as in the location where honeydew-producing insects were visited on the trees. Temporal and spatial segregation among hummingbird species is interpreted as an adaptation to reduce the risk of aggressive encounters. This may facilitate multispecies coexistence and allow these birds to exploit honeydew more effectively [Current Zoology 57 (1): 56–62, 2011].
A comprehensive field guide to the hummingbirds of the United States and Canada, covering 31 North American species with more than 220 photographs and 34 color maps. Though the primary focus is on field identification, the guide includes chapters on the natural history of hummingbirds, ways to attract and feed them, and major hot spots for watching these birds.
Coexistence between ecologically similar species can promote competition for resources. Hummingbirds (Aves: Trochilidae) are nectarivorous birds that usually coexist in sympatry, and visit flowers using different foraging behaviors and levels of aggressiveness as a strategy to diminish resource competition. Here, we describe the dynamics in territorial and dominance behaviors in a hummingbird community inhabiting a highland during winter in Western Mexico. We explored in natural conditions how foraging strategies and dominance status of the hummingbirds was influenced by community species composition, sex, age and size of the individuals, floral abundance, and nectar resource availability. The community studied was composed of 11 species (four residents, three altitudinal migrants, three latitudinal migrants), and all possible combinations of dominance and territoriality were found. Differences in the dominance status and foraging behavior were related to the species, sex, age and body size of the individuals, as well as the number of flowers in the patches, and the abundance of the migratory species over time. The aggressive and territorial species preferred the places with more flowers, and started the majority of the interactions attacking even birds that did not visited the flowers. The subordinate non-territorial hummingbirds visited floral patches of different sizes, did not start aggressive interactions and when they were involved in one, this occurred during their visits to the territorial hummingbird's flowers. Hummingbird dominance changed during the winter and at the end of the season, when the latitudinal migrant species left our study site, the resident species were more abundant, dominant and territorial. Dominance status and foraging behavior, together with floral preferences and the spatial distribution of nectar resources, acted as mechanisms organizing this hummingbird community.
Motion-induced sound is an intrinsic byproduct of essentially all animal behavior. Locomotion-induced sounds that have evolved specialization for communication are termed sonations. The null hypothesis is that locomotion-induced sounds are noncommunicative (adventitious), produced by nonspecialized morphology, and are involuntary. A sound is a sonation if it is produced by specialized morphology, or is produced voluntarily. The production of locomotion-induced sound can be examined at two levels: the animal motions (kinematics) that lead to sound production and the physical acoustic mechanism(s) that generate(s) the sound itself. The physical acoustics of locomotion induced sound are diverse, with both aerodynamic and structural mechanisms, including aeroelastic flutter, percussion, stridulation, and presumably many other undescribed mechanisms. There is a direct sound–motion correspondence between aspects of an animal’s motions and ensuing locomotion-induced sounds, especially in the time domain. This correspondence has two implications. One is experimental: sound recordings are a useful and perhaps underutilized source of data about animal locomotion. The second is behavioral: locomotion-induced sounds intrinsically contain information about an animal’s motions (such as wingbeat frequencies) that may be of interest to other animals. Therefore, locomotion-induced sounds are intrinsically suited to be mechanisms by which animals directly evaluate the locomotor performance of other animals, such as during courtship. The sound–motion correspondence is also a constraint. Sonations seem less acoustically diverse than vocalizations. Because they require discrete behaviors to be produced, animals also have somewhat fewer opportunities to produce sonations strategically, and few sonations are frequency-modulated. Sound production mechanisms of sonations are external to the animal and therefore are easy to manipulate experimentally on wild animals, making sonations an ideal, underutilized system for testing hypotheses about acoustic function.
Species occurrence patterns, and related processes of persistence, colonization and turnover, are increasingly being used to infer habitat suitability, predict species distributions, and measure biodiversity potential. The majority of these studies do not account for observational error in their analyses despite growing evidence suggesting that the sampling process can significantly influence species detection and subsequently, estimates of occurrence. We examined the potential biases of species occurrence patterns that can result from differences in detectability across species and habitat types using hierarchical multispecies occupancy models applied to a tropical bird community in an agricultural fragmented landscape. Our results suggest that detection varies widely among species and habitat types. Not incorporating detectability severely biased occupancy dynamics for many species by overestimating turnover rates, producing misleading patterns of persistence and colonization of agricultural habitats, and misclassifying species into ecological categories (i.e., forest specialists and generalists). This is of serious concern, given that most research on the ability of agricultural lands to maintain current levels of biodiversity by and large does not correct for differences in detectability. We strongly urge researchers to apply an inferential framework which explicitly account for differences in detectability to fully characterize species-habitat relationships, correctly guide biodiversity conservation in human-modified landscapes, and generate more accurate predictions of species responses to future changes in environmental conditions.
Nectar robbers are animals that extract the nectar produced by plants without effecting pollination. These animals can have negative, positive, or neutral effects on the interaction, depending on the direct and indirect effects of each participant in the system. The purpose of this work was to analyze the prevalence of nectar robbing and its temporal dynamics in a tropical highland forest in western Mexico. The system was studied in terms of the seasonal changes in (i) specific composition and abundance of hummingbird pollinators, their hosts, and the nectar robbers, (ii) use of resources by the nectarivorous birds and flowers, and (iii) prevalence of flower piercing by the cinnamon flowerpiercer, Diglossa baritula. The guild consisted of 17 species of hummingbirds, 2 species of nectar robbers, and 21 plant species that were visited by nectarivorous birds (robbers and pollinators). The relative abundance of birds and available flowers showed two peaks, one in winter and the other in the rainy season. Some plant species were used more than expected from their abundance. Overlap in the use of flowers among hummingbirds and also between hummingbirds and the nectar robbers was high. Nectar robbing was found to be widespread, occurring in almost all of the plants known to be hummingbird pollinated. The ratio of hummingbirds to nectar robbers was around 10 throughout the year.
Seed morphology has been an important taxonomic character for the Bromeliaceae, with three distinct seed types, naked, winged, and plumose, corresponding to the traditionally recognized subfamilies, Bromelioideae, Pitcairnioideae, and Tillandsioideae, respectively. In Tillandsioideae, the type of plumose seed appendage is used, in conjunction with other characters, to help circumscribe genera. For example, Catopsis, a genus of approximately 20 species, is characterized by having an apical coma of hairs, in contrast to Guzmania, Vriesea, and Tillandsia where seeds have a basal coma of hairs. The individual hairs, apical or basal, that comprise the plumose coma of the Tillandsioideae seeds have been assumed to be homologous structures. Scanning electron and light microscopy were used to examine the details of seed hair development in representative species of Catopsis and Tillandsia. Observations made in this study confirm published details of the basal seed hair development for Tillandsia. The apical seed hairs characteristic for Catopsis are shown to have a distinctly different ontogeny, and are judged to be synapomorphic for the genus. The apical and basal plumose seed appendages diagnostic for subfamily Tillandsioideae are analogous, but are not homologous in the ontogenetic or positional sense.
Resource-selection probability functions and occupancy models are powerful methods of identifying areas within a landscape that are highly used by a species. One common design/analysis method for estimation of a resource-selection probability function is to classify a sample of units as used or unused and estimate the probability of use as a function of independent variables using, for example, logistic regression. This method requires that resource units are correctly classified as unused (i.e., the species is never undetected in a used unit), or that the probability of misclassification is the same for all units. In this paper, I explore these issues, illustrating how misclassifying units as unused may lead to incorrect conclusions about resource use. I also show how recently developed occupancy models can be utilized within the resource-selection context to improve conclusions by explicitly accounting for detection probability. These models require that multiple surveys be conducted at each of a sample of resource units within a relatively short timeframe, but given the growing evidence from simulation studies and field data, I recommend that such procedures should be incorporated into studies of resource use.
Neotropical migratory songbirds typically breed in temperate regions and then travel long distances to spend the majority of the annual cycle in tropical wintering areas. Using stable-isotope methodology, we provide quantitative evidence of dual breeding ranges for 5 species of Neotropical migrants. Each is well known to have a Neotropical winter range and a breeding range in the United States and Canada. However, after their first bout of breeding in the north, many individuals migrate hundreds to thousands of kilometers south in midsummer to breed a second time during the same summer in coastal west Mexico or Baja California Sur. They then migrate further south to their final wintering areas in the Neotropics. Our discovery of dual breeding ranges in Neotropical migrants reveals a hitherto unrealized flexibility in life-history strategies for these species and underscores that demographic models and conservation plans must consider dual breeding for these migrants.
Incluye bibliografía e índice v.1. Ostrich to ducks.-- v.2. New world vultures to guineafowl.-- v.3. Hoatzin to auks.-- v.4. Sandgrouse to Cuckoos.-- v.5. Barn-owls to hummingbirds.-- v.6. Mousebirds to hornbills / Luis Baptista ... [et al.]
Theory predicts low niche differentiation between species over evolutionary time scales, but little empirical evidence is available. Reciprocal geographic predictions based on ecological niche models of sister taxon pairs of birds, mammals, and butterflies in southern Mexico indicate niche conservatism over several million years of independent evolution (between putative sister taxon pairs) but little conservatism at the level of families. Niche conservatism over such time scales indicates that speciation takes place in geographic, not ecological, dimensions and that ecological differences evolve later.
The spatial distribution of a natural resource is an important consideration in designing an efficient survey or monitoring program for the resource. Generally, sample sites that are spatially balanced, that is, more or less evenly dispersed over the extent of the resource, are more efficient than simple random sampling. We review a unified strategy for selecting spatially balanced probability samples of natural resources. The technique is based on creating a function that maps two-dimensional space into one-dimensional space, thereby defining an ordered spatial address. We use a restricted randomization to randomly order the addresses, so that systematic sampling along the randomly ordered linear structure results in a spatially well-balanced random sample. Variable inclusion probability, proportional to an arbitrary positive ancillary variable, is easily accommodated. The basic technique selects points in a two-dimensional continuum, but is also applicable to sampling finite populations or one-dimensional continua embedded in two-dimensional space. An extension of the basic technique gives a way to order the sample points so that any set of consecutively numbered points is in itself a spatially well-balanced sample. This latter property is extremely useful in adjusting the sample for the frame imperfections common in environmental sampling.
Aves de México: lista actualizada de especies y nombres comunes [Birds of Mexico: updated checklist of species and common names
- H Berlanga-García
- H Gómez De Silva
- V M Vargas-Canales
- V Rodríguez-Contreras
- L A Sánchez-González
- Berlanga-García H.
Berlanga-García H, Gómez de Silva H, Vargas-Canales VM,
Rodríguez-Contreras V, Sánchez-González LA, et al.
2015. Aves de México: lista actualizada de especies y
nombres comunes [Birds of Mexico: updated checklist
of species and common names]. Mexico City (México):
CONABIO.
Mexican land birds reveal complexity in fine-scale patterns of endemism
- S Bertelli
- C Szumik
- P A Goloboff
- N P Giannini
- A G Navarrosigüenza
Bertelli S, Szumik C, Goloboff PA, Giannini NP, NavarroSigüenza AG, et al. 2017. Mexican land birds reveal
complexity in fine-scale patterns of endemism. Journal
of Biogeography. doi:10.1111/jbi.12987
A guide to the birds of Mexico and Northern Central America
- Sng Howell
- S Webb
Howell SNG, Webb S. 1995. A guide to the birds of Mexico
and Northern Central America. Oxford (UK): Oxford
University Press.
Food and feeding habits of Mexican hummingbirds
- H O Wagner
- Wagner H.O.
Wagner HO. 1946. Food and feeding habits of Mexican
hummingbirds. Wilson Bulletin. 58:69-93.
Courtship behavior, vocalizations, and species limits in Atthis hummingbirds
- K Zykowski
- Townsend Peterson
- A Kluza
- Zykowski K.
Zykowski K, Townsend Peterson A, Kluza DA. 1998.
Courtship behavior, vocalizations, and species limits in
Atthis hummingbirds. Bulletin of the British Ornithologists' Club. 118:82-90.
Courtship behavior, vocalizations, and species limits in hummingbirds
- K Zykowski
- Townsend Peterson
- A Kluza
Conservación de especies migratorias y poblaciones transfronterizas [Conservation of migratory species and transfrontier populations]
- R A Medellín
- A Abreu-Grobois
- M C Arizmendi
- E Mellink
- E Ruelas
- Medellín R.A.