Article

Finding food in the open ocean: foraging strategies in Humboldt Penguins

Article

Finding food in the open ocean: foraging strategies in Humboldt Penguins

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Abstract

Penguins are excellent "model" organisms allowing us to study the behaviour of marine homeotherms at sea. Penguins regularly return to their breeding colonies, enabling biologists to equip them with remote sensing devices such as physiological or behavioural data-loggers, radio- or satellite transmitters. Foraging trips at sea can last from days to weeks and after return of the birds to their breeding sites, the devices can easily be removed for analysis of on-board stored data, yielding a wealth of information. Investigation of penguin behaviour at sea becomes particularly revealing when other sources of information can be matched to the data set, such as satellite data on wind, temperature, ice cover, and chlorophyll-a concentrations. Penguins and other marine homeotherms are true inhabitants of the high seas. Depending on the season, the marine behaviour varies: during reproduction, penguins are central-place foragers, and must return regularly to their nest to feed their chicks. During the remainder of the year, there are no constraints and the birds travel large distances at sea. Breeding Humboldt penguins react to climatic change by varying their daily foraging range and dive duration. Similar to other representatives of the family Spheniscidae, Humboldt penguins avoid food shortages by migrating into more productive marine areas. Navigational clues such as daylength, sea surface temperature, local wind direction and olfaction might provide important aids in finding patchily distributed prey in the open ocean. DMS, a chemical compound produced by decaying algae, seems to be a further clue that indirectly points the way to feeding areas.

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... Original observations by Culik et al. (2000) on Humboldt penguins Spheniscus humboldti first suggested a role for olfaction in penguin foraging, as birds appeared to use winds to find food during an El Niño event. Later, Culik (2001) confirmed that captive Humboldt penguins could detect DMS. Cunningham et al. (2008) showed DMS sensitivities in wild African penguins S. demersus by placing the odourant along walkways in their colony on Robben Island, South Africa and with captive penguins using a Y-maze. ...
... Sensitivity to DMS has now been shown in four species of penguin: African (Cunningham et al. 2008, Wright et al. 2011, Humboldt (Culik 2001), chinstrap (Amo et al. 2013), and king (this study). Given the close evolutionary relationship between penguins and procellariiforms (Ksepka et al. 2006, Hackett et al. 2008, the sensitivity to this odourant by penguins is not surprising. ...
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Increasing evidence suggests that penguins are sensitive to dimethyl sulphide (DMS), a scented airborne compound that a variety of marine animals use to find productive areas of the ocean where prey is likely to be found. Here we present data showing that king penguins Aptenodytes patagonicus are also sensitive to DMS. We deployed DMS on a lake near a king penguin colony at Ratmanoff beach in the Kerguelen archipelago. We also presented DMS to 'sleeping' adults on the beach. On the lake, penguins responded to the DMS deployments by swimming more, while on the beach, penguins twitched their heads and woke up more for the DMS than for the control presentations. Interestingly, penguins did not respond to cod liver oil deployments on the lake; mirroring at-sea studies of other penguins. Although at-sea studies are needed to confirm that king penguins use DMS as a surface cue that informs them of productivity under the water, this study is an important first step in understanding how these birds locate prey over significant distances.
... Numerous studies have confirmed this, as procellariiforms are attracted to a variety of prey-related odours at sea such as fishy smelling compounds and the scent of krill (Nevitt, 1999b). By contrast, it is typically thought that penguins are primarily visual hunters (Wilson et al., 1993;Wilson and Wilson, 1995;Ryan et al., 2007), and the potential use of olfactory cues by penguins for foraging has largely been ignored (but see Culik et al., 2000;Culik, 2001). ...
... (short/long) and 1.4/6.7 days, respectively (Chaurand and Weimerskirch, 1994;Duriez et al., 2000). This is the first study to clearly demonstrate, by way of experimentation, that a penguin is able to detect an odour (see also Culik et al., 2000;Culik, 2001). Although the present study does not directly test DMS as a foraging cue, it does implicate the use of odours by penguins while hunting. ...
Article
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Although it is well established that certain procellariiform seabirds use odour cues to find prey, it is not clear whether penguins use olfactory cues to forage. It is commonly assumed that penguins lack a sense of smell, yet they are closely related to procellariiforms and forage on similar types of prey in similar areas to many procellariiforms. Such regions are characterized by having high levels of dimethyl sulphide (DMS) a scented compound that many marine animals use to locate foraging grounds. If penguins can smell, DMS may be a biologically relevant scented compound that they may be sensitive to in nature. To test this hypothesis, we investigated whether adult African penguins (Spheniscus demersus) could detect DMS using two separate experiments. We tested wild penguins on Robben Island, South Africa, by deploying mumolar DMS solutions in the colonies, and found that birds slowed down their walking speeds. We also tested captive penguins in a Y-maze. In both cases, our data convincingly demonstrate that African penguins have a functioning sense of smell and are attracted to DMS. The implication of this work is that the detection of changes in the odour landscape (DMS) may assist penguins in identifying productive areas of the ocean for foraging. At-sea studies are needed to investigate this issue further.
... Numerous studies have confirmed this, as procellariiforms are attracted to a variety of prey-related odours at sea such as fishy smelling compounds and the scent of krill (Nevitt, 1999b). By contrast, it is typically thought that penguins are primarily visual hunters (Wilson et al., 1993;Wilson and Wilson, 1995;Ryan et al., 2007), and the potential use of olfactory cues by penguins for foraging has largely been ignored (but see Culik et al., 2000;Culik, 2001). ...
... (short/long) and 1.4/6.7 days, respectively (Chaurand and Weimerskirch, 1994;Duriez et al., 2000). This is the first study to clearly demonstrate, by way of experimentation, that a penguin is able to detect an odour (see also Culik et al., 2000;Culik, 2001). Although the present study does not directly test DMS as a foraging cue, it does implicate the use of odours by penguins while hunting. ...
... Procellariform seabirds, including storm petrels, prions, petrels, and albatross are all sensitive to DMS and use it as an indicator of their main source of food 56 . There is also evidence that Humboldt penguins can use DMS to track upwind plankton blooms over long distances 57 . ...
Article
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Many bird species have the ability to navigate home after being brought to a remote, even unfamiliar location. Environmental odours have been demonstrated to be critical to homeward navigation in over 40 years of experiments, yet the chemical identity of the odours has remained unknown. In this study, we investigate potential chemical navigational cues by measuring volatile organic compounds (VOCs): at the birds' home-loft; in selected regional forest environments; and from an aircraft at 180 m. The measurements showed clear regional, horizontal and vertical spatial gradients that can form the basis of an olfactory map for marine emissions (dimethyl sulphide, DMS), biogenic compounds (terpenoids) and anthropogenic mixed air (aromatic compounds), and temporal changes consistent with a sea-breeze system. Air masses trajectories are used to examine GPS tracks from released birds, suggesting that local DMS concentrations alter their flight directions in predictable ways. This dataset reveals multiple regional-scale real-world chemical gradients that can form the basis of an olfactory map suitable for homing pigeons.
... Differences in the olfactory abilities among birds reflect diverse specialized functions, such as foraging, orientation/navigation, homing, nesting, activity pattern, and individual recognition (Cobb 1959;Cobb 1960;Bang 1965;Bang and Cobb 1968;Bang 1971;Bang and Wenzel 1985;Waldvogel 1989;Healy and Guilford 1990;Papi 1991;Culik 2001;Wallraff 2001;Bonadonna and Nevitt 2004;Van Buskirk and Nevitt 2008;Zelenitsky et al. 2011). These complex behaviors depend on multiple modes of perception, and the observed differences in OR subgenomes described here are possibly interrelated with other sensorial abilities, including vision and vocalizations (Martin et al. 2004;Nevitt et al. 2004;Partan and Marler 2005;Hagelin and Jones 2007). ...
Article
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Olfactory receptors (ORs) govern a prime sensory function. Extant birds have distinct olfactory abilities, but the molecular mechanisms underlining diversification and specialization remain mostly unknown. We explored OR diversity in 48 phylogenetic and ecologically diverse birds and 2 reptiles (alligator and green sea turtle). OR subgenomes showed species- and lineage-specific variation related with ecological requirements. Overall 1,953 OR genes were identified in reptiles and 16,503 in birds. The two reptiles had larger OR gene repertoires (989 and 964 genes, respectively) than birds (182-688 genes). Overall, birds had more pseudogenes (7,855) than intact genes (1,944). The alligator had significantly more functional genes than sea turtle, likely because of distinct foraging habits. We found rapid species-specific expansion and positive selection in OR14 (detects hydrophobic compounds) in birds and in OR51 and OR52 (detect hydrophilic compounds) in sea turtle, suggestive of terrestrial and aquatic adaptations, respectively. Ecological partitioning among birds of prey, water birds, land birds, and vocal learners showed that diverse ecological factors determined olfactory ability and influenced corresponding olfactory-receptor subgenome. OR5/8/9 was expanded in predatory birds and alligator, suggesting adaptive specialization for carnivory. OR families 2/13, 51, and 52 were correlated with aquatic adaptations (water birds), OR families 6 and 10 were more pronounced in vocal-learning birds, whereas most specialized land birds had an expanded OR family 14. Olfactory bulb ratio (OBR) and OR gene repertoire were correlated. Birds that forage for prey (carnivores/piscivores) had relatively complex OBR and OR gene repertoires compared with modern birds, including passerines, perhaps due to highly developed cognitive capacities facilitating foraging innovations.
... Cunningham and colleagues demonstrated through a series of land-based experiments that African penguins Spheniscus demersus Linnaeus respond to DMS at concentrations typical of those found in their natural foraging environment (Cunningham et al., 2008). The use of DMS for detecting prey patches has also been suggested for Humboldt penguins S. humboldti (Culik, 2001; Culik et al., 2000). However, at sea, experiments to demonstrate the reaction of penguins to odorants have not been attempted. ...
Article
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Breeding Spheniscus penguins are central place foragers that feed primarily on schooling pelagic fish. They are visual hunters, but it is unclear how they locate prey patches on a coarse scale. Many petrels and storm petrels (Procellariiformes), the penguins' closest relatives, use olfactory cues to locate prey concentrations at sea, but this has not been demonstrated for penguins. Procellariiforms are attracted to a variety of olfactory cues, including dimethyl sulphide (DMS), an organosulphur compound released when phytoplankton is grazed, as well as fish odorants such as cod liver oil. A recent study found that African penguins Spheniscus demersus react to DMS on land. We confirm this result and show that African penguins are also attracted by DMS at sea. DMS-scented oil slicks attracted 2-3 times more penguins than control slicks, whereas penguins showed no response to slicks containing cod liver oil. The number of penguins attracted to DMS increased for at least 30 min, suggesting penguins could travel up to 2 km to reach scent cues. Repeats of land-based trials confirmed previous results showing DMS sensitivity of penguins on land. Our results also support the hypothesis that African penguins use DMS as an olfactory cue to locate prey patches at sea from a distance, which is particularly important given their slow commuting speed relative to that of flying seabirds.
... Marine predators can cue in on signals emitted by prey to estimate the local densities or quality of prey. They rely on their sensory systems such as olfaction [12,13], echolocation [14] or, in most of the cases, vision [15,16] to detect these signals. Unlike odontocetes, pinnipeds do not echolocate to find their prey [17]. ...
Article
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How non-echolocating deep diving marine predators locate their prey while foraging remains mostly unknown. Female southern elephant seals (SES) (Mirounga leonina) have vision adapted to low intensity light with a peak sensitivity at 485 nm. This matches the wavelength of bioluminescence produced by a large range of marine organisms including myctophid fish, SES's main prey. In this study, we investigated whether bioluminescence provides an accurate estimate of prey occurrence for SES. To do so, four SES were satellite-tracked during their post-breeding foraging trip and were equipped with Time-Depth-Recorders that also recorded light levels every two seconds. A total of 3386 dives were processed through a light-treatment model that detected light events higher than ambient level, i.e. bioluminescence events. The number of bioluminescence events was related to an index of foraging intensity for SES dives deep enough to avoid the influence of natural ambient light. The occurrence of bioluminescence was found to be negatively related to depth both at night and day. Foraging intensity was also positively related to bioluminescence both during day and night. This result suggests that bioluminescence likely provides SES with valuable indications of prey occurrence and might be a key element in predator-prey interactions in deep-dark marine environments.
... These changes also affect the abundance and availability of prey species (Arntz & Fahrbach 1991. To survive and to breed under such variable ecological conditions, Humboldt penguins should be able to adjust their foraging behaviour to the different oceanographic conditions of their habitat , Culik 2001. ...
Article
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During the austral summer 1998/1999, we compared foraging ecology and reproduction between chick-rearing Humboldt penguins Spheniscus humboldti at 2 colonies in Chile. At Pan de Azucar in northern Chile prey availability was assumed to be lower than at Punihuil, 1500 km further south, according to oceanographic data. Fifteen adult penguins were equipped with temperature-depth recorders and stomach-temperature-loggers in order to investigate foraging effort and foraging success in relation to differences in prey availability. There were no differences between colonies in diving behaviour. At Pan de Azucar, foraging trips were longer than at Punihuil (mean duration 36.5 +/- 7.8 h vs. 19.0 +/- 8.7 h), resulting in higher energy expenditure per foraging trip (on average 8092.7 +/- 2216.7 kJ vs. 3934.5 kJ, range: 3071 to 7930 kJ). Catch per unit effort at Pan de Azucar equalled 2.2 1.4 g min(-1) under water, which was significantly less than 10.0 +/- 7.3 g min(-1) at Punihuil. As a result of higher energetic costs and lower foraging success, the gross foraging efficiency per foraging trip (GFE) was lower at Pan de Azucar than at Punihuil (on average 0.94 +/- 0.52 vs. 4.61 +/- 3.4 [kJ gained/kJ invested]). The chick growth rates at Pan de Azucar (mass: 40.0 +/- 18.4 g d(-1) vs. 63.0 +/- 23.0 g d(-1); bill length: 0.32 +/- 0.07 mm d(-1) vs. 0.47 +/- 0.12 mm d(-1)), as well as chick survival (40% vs. 100%) and reproductive success (0.33 vs. 0.81 fledglings nest(-1)), were lower compared to Punihuil. A GFE threshold of 1.08 was calculated for chick survival at Pan de Azucar. We conclude that due to physiological and morphological constraints the penguins at Pan de Azucar could not increase diving effort to compensate for lower prey availability, but took extended foraging trips instead. Therefore, foraging efficiency and meal delivery rate decreased, resulting in less chick growth and lower reproductive success.
... Mackiernan et al. 2001) and large numbers of dead and dying birds at several places throughout the eastern Pacific (Ainley et al. 1988, Duffy 1990). ENSO-related southward migration of top-predators relying on the Humboldt Current ecosystem has been observed in guano birds (Arntz & Fahrbach 1991) as well as Humboldt penguins (Culik 2001). Adult seabirds often did not attempt to breed (e.g. ...
Article
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The coastal and oceanic waters around the South American coasts provide rich foraging grounds for breeding and wintering seabirds, but there is growing concern that climate change will provide additional pressures to the seabirds around South America. As in many other coastal ecosystems, seabirds around South America are already faced with threats to their breeding habitats such as human disturbance and introduced predators, and threats at sea such as persistent pollutants and pesticides and direct mortality risks due to fisheries and oil spills. The sensitivity of South American marine ecosystems to ocean climate anomalies is well known from the dramatic population collapses caused by El Niño Southern Oscillation (ENSO) events. However, longer-term climate change effects have been explored less often and few long-term data sets exist for South American seabirds. Seven Large Marine Ecosystems (LME) border South America. While all LMEs experienced warming during the last 50 years, their climate dynamics have differed in recent decades. Climate models suggest that potential climate change effects may be important, especially due to changes in ENSO intensity and frequency and associated changes in the ocean climate of Atlantic and Pacific marine ecosystems. In this review, we found that the best studied seabird communities are those of the Patagonian Shelf and the Humboldt Current, but overall, our knowledge on climate effects on South American seabirds is scarce.
... To date, detection of this compound has been described in several species of procelariiform seabirds (Nevitt et al. 1995, Nevitt & Haberman 2003, Bonadonna et al. 2006, Nevitt 2008 and in the African penguin Spheniscus demersus (Cunningham et al. 2008, Wright et al. 2011, and it has also been suggested for Humboldt penguins S. humboldti (Culik 2001), which all forage on fish. As yet there is no evidence of DMS detection in krill-feeding penguins. ...
Article
In response to zooplankton grazing, phytoplankton release dimethylsulphoniopropionate in the seawater, which is then catabolized to dimethyl sulphide (DMS) that is emitted to the air. This molecule therefore signals areas of high productivity in the oceans, and it can be used by predators for locating foraging areas. Detection of this compound has been described in several species of procelariiform seabirds and non-Antarctic fish-feeding penguins. However, there is no evidence of DMS detection by krill-feeding penguins. The mechanisms of krill detection by its predators are especially relevant in Antarctica, where trophic webs are mainly based on krill. We explored for the first time whether a krill-feeding penguin species, the chinstrap penguin Pygoscelis antarctica, is able to detect DMS. We examined whether chinstrap penguins could detect DMS by locating DMS or control recipients in pathways that penguins used when moving between the colony and the sea. We also analysed the attraction of nestling penguins to DMS in a T-shaped experimental enclosure. Our results showed that adult penguins are attracted to DMS on land. Nestling penguins also tended to be attracted to the scent of DMS. Further research is needed to examine whether chinstrap penguins use natural DMS concentrations as a foraging cue at sea.
... Mackiernan et al. 2001) and large numbers of dead and dying birds at several places throughout the eastern Pacific (Ainley et al. 1988, Duffy 1990). ENSO-related southward migration of top-predators relying on the Humboldt Current ecosystem has been observed in guano birds (Arntz & Fahrbach 1991) as well as Humboldt penguins (Culik 2001). Adult seabirds often did not attempt to breed (e.g. ...
Article
Full-text available
The coastal and oceanic waters around the South American coasts provide rich foraging grounds to breeding and wintering seabirds, but there is growing concern that climate change will add additional pressures to the seabirds around South America. As in many other coastal ecosystems, seabirds around South America are already faced with threats in the breeding habitat such as human disturbance and introduced predators, and threats at sea such as persistent pollutants and pesticides and direct mortality risks due to fisheries and oil spills. The sensitivity of South American marine ecosystems to ocean climate anomalies is well known from the dramatic population collapses caused by El Niño Southern Oscillation (ENSO) events. However, longer-term climate change effects have less often been explored, and few long-term data sets exist from South American seabirds. Seven Large Marine Ecosystems (LME) border South America. While all LME experienced warming during the last 50 years, their climate dynamics differed in the last decades. In this review we aim to summarize the current knowledge on seabird responses to global warming in South American waters, identify gaps in our knowledge about the responses of seabirds to climate change and thus, propose new lines of research. Key words: Aves, climate change, ENSO, South America, coastal ocean ecosystems
... Mackiernan et al. 2001) and large numbers of dead and dying birds at several places throughout the eastern Pacific (Ainley et al. 1988, Duffy 1990). ENSO-related southward migration of top-predators relying on the Humboldt Current ecosystem has been observed in guano birds (Arntz & Fahrbach 1991) as well as Humboldt penguins (Culik 2001). Adult seabirds often did not attempt to breed (e.g. ...
Article
Full-text available
The coastal and oceanic waters around the South American coasts provide rich foraging grounds to breeding and wintering seabirds, but there is growing concern that climate change will add additional pressures to the seabirds around South America. As in many other coastal ecosystems, seabirds around South America are already faced with threats in the breeding habitat such as human disturbance and introduced predators, and threats at sea such as persistent pollutants and pesticides and direct mortality risks due to fisheries and oil spills. The sensitivity of South American marine ecosystems to ocean climate anomalies is well known from the dramatic population collapses caused by El Niño Southern Oscillation (ENSO) events. However, longer-term climate change effects have less often been explored, and few long-term data sets exist from South American seabirds. Seven Large Marine Ecosystems (LME) border South America. While all LME experienced warming during the last 50 years, their climate dynamics differed in the last decades. In this review we aim to summarize the current knowledge on seabird responses to global warming in South American waters, identify gaps in our knowledge about the responses of seabirds to climate change and thus, propose new lines of research. Key words: Aves, climate change, ENSO, South America, coastal ocean ecosystems
... This perspective, traditionally limited to the study of olfactory navigation, both in the context of homing (see Wallraff 2004 ) and identi fi cation of feeding areas (Nevitt 2000(Nevitt , 2008Nevitt et al. 2006 ;Nevitt and Bonadonna 2005 ) , has been recently enriched by new evidence from other bird species. For instance, similar to procellariiforms, penguins have been shown to detect feeding areas by smell (Culik 2001 ;Cunningham et al. 2008 ;Wright et al. 2011 ) . Land birds, such as passerines and parrots, may also be conditioned to fi nd food near a given odour (Hagelin 2004 ;Mennerat et al. 2005 ;Roper 2003 ) . ...
Chapter
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Odours are broadly used for individual, sexual and species recognition in vertebrates and may be reliable signals of quality and compatibility. Yet, chemical signals in birds have rarely been investigated. In fact, birds exhibit a wide array of communication mechanisms (e.g. colours and calls) but rarely display obvious olfactory-driven behaviours. This is probably why, despite three decades of physiological and behavioural studies establishing the existence of avian olfactory functions, chemical communication has been essentially ignored.
... The observed foraging ranges are in accord with previous studies conducted at other colonies of Humboldt Penguins. Although breeding adults can forage up to 90 km around a colony (Culik & Luna-Jorquera 1997, Culik 2001, they are usually found within 35 km the colony during the period of parental care (Luna-Jorquera & Culik 2000, Taylor et al. 2002, Boersma et al. 2007). Our results indicate that trips observed around Tilgo Island range widely, extending over a large coastal zone (Fig. 1). ...
Article
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The largest population of Humboldt Penguins resides in a fertile archipelago of the north-central coast of Chile, formed by eight islands in proximity to upwelling centers of the Humboldt Current System. However, five of these islands lack legal protection. Here, we report the results of breeding Humboldt Penguins tracked while foraging from Tilgo Island. The average and maximum foraging radii around the colony were 22 km and 43 km, respectively. Our data indicate that trip ranges overlap areas proposed for industrial projects. Because Humboldt Penguins are sentinels of local ecosystem health, this underscores the value of expanding conservation zones in this unique marine location.
... Petrels, albatross, and prions, for example, can detect and localize high prey abundance using the odors (dimethyl sulfide and pyrazines) produced by phytoplankton when grazed by zooplankton as they forage out at sea (e.g., Grubb, 1972;Hutchison and Wenzel, 1980;Nevitt et al., 1995;Nevitt, 2000;Nevitt and Haberman, 2003;Nevitt and Bonadonna, 2005;Bonadonna et al., 2006;Dell'Ariccia and Bonadonna, 2013). The same likely applies to other semi-aquatic and also aquatic species, however, to date this has only been shown in penguins (Spheniscidae), which use dimethyl sulfide as a behavioral cue to track upwind plankton blooms over long distances (Culik, 2001;Cunningham et al., 2008;Wright et al., 2011). ...
Article
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The relative size of olfactory bulbs (OBs) is correlated with olfactory capabilities across vertebrates and is widely used to assess the relative importance of olfaction to a species' ecology. In birds, variations in the relative size of OBs are correlated with some behaviors; however, the factors that have led to the high level of diversity seen in OB sizes across birds are still not well understood. In this study, we use the relative size of OBs as a neuroanatomical proxy for olfactory capabilities in 135 species of birds, representing 21 orders. We examine the scaling of OBs with brain size across avian orders, determine likely ancestral states and test for correlations between OB sizes and habitat, ecology, and behavior. The size of avian OBs varied with the size of the brain and this allometric relationship was for the most part isometric, although species did deviate from this trend. Large OBs were characteristic of more basal species and in more recently derived species the OBs were small. Living and foraging in a semi-aquatic environment was the strongest variable driving the evolution of large OBs in birds; olfaction may provide cues for navigation and foraging in this otherwise featureless environment. Some of the diversity in OB sizes was also undoubtedly due to differences in migratory behavior, foraging strategies and social structure. In summary, relative OB size in birds reflect allometry, phylogeny and behavior in ways that parallel that of other vertebrate classes. This provides comparative evidence that supports recent experimental studies into avian olfaction and suggests that olfaction is an important sensory modality for all avian species.
... Equally interesting is that burrow nesting appears to be an ancestral trait, suggesting that some degree of DMS sensitivity may also have been an ancestral condition for the Procellariiformes and their sister order, the Sphenisciformes (penguins). Penguins are generally not thought to be particularly olfactory birds, but since they also forage in productive areas that are characterized by high levels of DMS (Culik, 2001), their olfactory abilities should be further investigated. Interestingly, little penguins (Eudyptula minor) not only nest underground but also show tube-like structures on their nares during development (Kinsky, 1960). ...
Article
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Procellariiform seabirds wander the world's oceans aided by olfactory abilities rivaling those of any animal on earth. Over the past 15 years, I have been privileged to study the sensory ecology of procellariiforms, focusing on how olfaction contributes to behaviors, ranging from foraging and navigation to individual odor recognition, in a broader sensory context. We have developed a number of field techniques for measuring both olfactory- and visually based behaviors in chicks and adults of various species. Our choice of test odors has been informed by long-term dietary studies and geochemical data on the production and distribution of identifiable, scented compounds found in productive waters. This multidisciplinary approach has shown us that odors provide different information over the ocean depending on the spatial scale. At large spatial scales (thousands of square kilometers), an olfactory landscape superimposed upon the ocean surface reflects oceanographic or bathymetric features where phytoplankton accumulate and an area-restricted search for prey is likely to be successful. At small spatial scales (tens to hundreds of square kilometers), birds use odors and visual cues to pinpoint and capture prey directly. We have further identified species-specific, sensory-based foraging strategies, which we have begun to explore in evolutionary and developmental contexts. With respect to chemical communication among individuals, we have shown that some species can distinguish familiar individuals by scent cues alone. We are now set to explore the mechanistic basis for these discriminatory abilities in the context of kin recognition, and whether or not the major histocompatibility complex is involved.
... For non-flighted species, such as penguins, the benefits of local enhancement are reduced due to their visual perspective being limited to the field of view at the sea surface (Haney et al. 1992) and their inability to traverse large areas with the aid of flight. Despite this, penguins can effectively track the distribution of their patchy prey (Carroll et al. 2017) and, although this is partly achieved through olfaction based on indirect signals of prey (Culik et al. 2000, Culik 2001, Wright et al. 2011, it is likely that this ability is also facilitated through other sensory modalities. ...
Article
Social cohesion and prey location in seabirds are largely enabled through visual and olfactory signals, but these behavioural aspects could potentially also be enhanced through acoustic transfer of information. Should this be the case, calling behaviour could be influenced by different social‐ecological stimuli. African Penguins Spheniscus demersus were equipped with animal‐born video recorders to determine if the frequency and types of calls emitted at sea were dependent on behavioural modes (commuting, sedentary and dive bout) and social status (solitary versus group). For foraging dive bouts we assessed whether the timing and frequency of calls were significantly different in the presence of schooling prey versus single fish. The probability of call events were significantly more likely for birds commuting early and late in the day (for solitary birds) and during dive bouts (for groups). During foraging dive bouts the frequency of calls was significantly greater for birds diving in the presence of schooling fish and birds called sooner after a catch in these foraging scenarios compared to when only single fish were encountered. Three call types were recorded, 'flat', 'modulated' and 'two‐voices' calls but there was no significant relationship detected with these call types and behavioural modes for solitary birds and birds in groups. Results of this study show that acoustic signalling by African Penguins at sea is used in a variety of behavioural contexts and that increased calling activity in the presence of more profitable prey could be of crucial importance to seabirds that benefit from group foraging.
... However, information on foraging behaviour in nonbreeding Humboldt Penguins is sparse. Studies from Chile using a small number of satellite and radio-tagged birds have shown that non-breeding adults travel farther from the breeding colony than do breeding birds (Culik & Luna-Jorquera 1997a, 1997bCulik et al. 1998;Culik et al. 2000;Culik 2001). However, except for one study during El Niño, when adults may change their behaviour in response to changes in prey distribution (Culik et al. 2000), no information is available on foraging behaviour per se (e.g. ...
Article
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At Punta San Juan, Peru, we examined the foraging behaviour of three Humboldt Penguins Spheniscus humboldti following breeding failure, and we compared that behaviour with the behaviour of 22 breeding birds with chicks. Failed breeders appear to take longer foraging trips, to make deeper and longer dives and to dive less often per hour at sea than breeding birds do. We suggest that failed breeders either take longer foraging trips to reduce the number of trips they make to the colony, which reduces the costs of transit, or they travel to more distant foraging areas, as documented for Chile. Study of non-breeding birds that have successfully fledged young would help to clarify the differences in foraging behaviour between non-breeding and breeding birds.
... Heath (1987) used a contact cement to affix a Velcro fabric base on the backs of penguins (Spheniscidae) and Velcro fabric on the transmitter to provide a fast means of replacing transmitters. Wilson and Wilson (1989), Culik (2001), and others have wrapped feathers and a transmitter in Tesa tape to hold transmitters on penguins. Suturing has been used to attach small transmitters to the backs of young precocial birds (Burkpile et al 2002). ...
... In contrast to the migratory Magellanic Penguin, Humboldt Penguins are considered sedentary (Croxall and Davis, 1999;Williams, 1995), although there are indications that Humboldt Penguins may travel several hundreds of kilometres during El Niño events (e.g. Culik, 2001;Culik and Luna-Jorquera, 1997;Culik et al., 2000;Wallace et al., 1999). ...
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Ten Humboldt (Spheniscus humboldti) and eight Magellanic Penguins (S. magellanicus) were successfully equipped with satellite transmitters in March 2009 on Islotes Puñihuil in central south-Chile to follow their post-moult dispersal. Overall, Humboldt Penguins could be followed for a mean period of 49 ±18 days (range: 25–93) and Magellanic Penguins for 57 ±12 days (range 35–68). Irrespective of species and sex, seven study birds remained in the vicinity of their breeding ground throughout the transmission period. All other penguins moved northwards, either only a relatively short distance (max 400 km) to Isla Mocha at 38°S (n=3) or further north beyond 35°S (n=8). However, eight of these birds (73%) turned south again towards the end of the individual tracking periods. The total area used by both species during the tracking period was restricted to a coastal area stretching from the breeding site at 42°S about 1000 km to the north at about 32°S. The area used by Humboldt penguins overlapped by 95% the area used by Magellanic penguins, whereas the area used by the latter species was much larger and overlapped only by 45% with the area used by Humboldt penguins. Overall, our results indicate that Magellanic Penguins in the Pacific Ocean are probably less migratory than their conspecifics on the Atlantic side, while Humboldt Penguins appear to be more migratory than previously anticipated. In general, there was a poor relationship between preferred foraging areas and chlorophyll-a, as a proxy for primary productivity, indicating the limitations of using remote-sensed primary productivity as a proxy to interpret the foraging behaviour of marine predators. In addition, there was also no clear relationship between the preferred foraging areas and the amount of regional fish catches by artisanal fishery.
... The similarity in feather Hg levels between both northern penguin colonies (Pan de Azúcar Island and Isla Grande; Fig. 4B) could be associated with historical mining pollution, because feathers act as indicators of long-term exposure (compared with blood) (Ochoa-Acuña et al. 2002;Brasso and Polito 2013;Carravieri et al. 2016). Given that Humboldt penguins off the breeding season can travel large distances (> 150 km ;Culik 2001), feather Hg concentrations would not be indicative of local pollution. Conversely, differences in blood Hg concentrations between penguins of both colonies (Fig. 4A) reflect recent dietary exposure (Finger et al. 2015), either at the time of sampling or the breeding season. ...
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Penguins are reliable sentinels for environmental assessments of mercury (Hg) due to their longevity, abundance, high trophic level, and relatively small foraging areas. We analyzed Hg concentrations from blood and feathers of adult Humboldt penguins (Spheniscus humboldti) and feathers of chinstrap penguins (Pygoscelis antarcticus) from different reproductive colonies with variable degrees of urbanization and industrialization along the Chilean and Antarctic coasts. We evaluated Hg concentration differences between species, sexes (Humboldt penguins), and localities. Our results showed significantly greater levels in Humboldt penguins than in chinstrap penguins and nonsignificant differences between sexes among Humboldts. Penguin Hg concentrations showed a latitudinal pattern, with greater values of the metal at lower latitudes, independent of the species. Both studied penguin species showed elevated Hg concentrations compared to their congeners, highlighting the necessity to investigate potential negative effects on their populations. Although differences between species are possibly due to variation in diet and trophic level, our results suggest an important effect of the degree of Hg pollution adjacent to foraging areas. Further research on Hg content in prey species and environmental samples, together with a larger overall sample size, and investigation on penguin’s diet and trophic level are needed to elucidate Hg bioavailability in each location and the role of local Hg pollution levels. Likewise, it is important to monitor Hg and other heavy metals of ecotoxicological importance in penguin populations in vulnerable regions of Chile.
... However, pressures that govern wild behavior, such as competition, predation, and foraging, are absent in captivity [Williams and Hoffman, 2009] and hence behavioral deviations may be a product of selection relaxation rather than enclosure design [Melfi, 2009]. More specifically for S. humboldti, time spent at sea is influenced by environmental variables and anthropogenic influences that limit prey availability, visibility and therefore foraging effort [Culik and Luna-Jorquera, 1997;Culik, 2001]. Accordingly, where food is routinely provided in zoos without having to enter the water, a deviation from aquatic behavior is expected, though not necessarily a welfare concern. ...
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Multi-zoo comparisons of animal welfare are rare, and yet vital for ensuring continued improvement of zoo enclosures and husbandry. Methods are not standardised for the development of zoo enclosures based on multiple indicators, and case study species are required. This study compares behaviour and breeding success to various enclosure and husbandry parameters for the Humboldt penguin, Spheniscus humboldti, for the development of improved enclosure design. Behavioural sampling was completed at Flamingo Land over a period of eight months. Further data on behaviour, enclosure design and breeding success were collected via questionnaires, visits to zoos, and literature review. Breeding success was primarily influenced by colony age and number of breeding pairs, suggesting an important social influence on reproduction. Across zoos, there was also significant variation in behaviour. The proportion of time spent in water varied between zoos (2-23%) and was used as an indicator of physical activity and natural behaviour. Regression models revealed that water-use was best predicted by total enclosure area per penguin, followed by land area, with some evidence for positive influence of pool surface area per penguin. Predominantly linear/curvilinear increases in our biological indicators with enclosure parameters suggest that optimal conditions for S. humboldti were not met among the selected zoos. We propose revised minimum conditions for S. humboldti enclosure design, which exceed those in the existing husbandry guidelines. We present a framework for the evaluation of zoo enclosures and suggest that a rigorous scientific protocol be established for the design of new enclosures, based on multivariate methods.
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Studies of kin recognition in birds have largely focused on parent-offspring recognition using auditory or visual discrimination. Recent studies indicate that birds use odors during social and familial interactions and possibly for mate choice, suggesting olfactory cues may mediate kin recognition as well. Here, we show that Humboldt penguins (Spheniscus humboldti), a natally philopatric species with lifetime monogamy, discriminate between familiar and unfamiliar non-kin odors (using prior association) and between unfamiliar kin and non-kin odors (using phenotype matching). Penguins preferred familiar non-kin odors, which may be associated with the recognition of nest mates and colony mates and with locating burrows at night after foraging. In tests of kin recognition, penguins preferred unfamiliar non-kin odors. Penguins may have perceived non-kin odors as novel because they did not match the birds' recognition templates. Phenotype matching is likely the primary mechanism for kin recognition within the colony to avoid inbreeding. To our knowledge this is the first study to provide evidence of odor-based kin discrimination in a bird.
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In chickens, food consumption can be altered by exposing the chicks to scents as embryos. We exposed eggs to an orange-scented food additive in the final days of incubation. Following hatching, we tested these exposed chicks' ability to detect this scent at a variety of concentrations. We found that orange-exposed chicks responded to an orange-scented solution at lower concentrations than control chicks. This sensitization may allow chicks to be more effective at locating acceptable food items but requires further testing to determine its significance. Orange-exposed and control chicks were also tested with the scent of raspberry. Orange-exposed chicks responded to the raspberry presentation significantly more than the control chicks did, suggesting that the embryonic exposure to orange may have influenced how the chicks responded towards another fruity smell. This result suggests that chicks may be learning general characteristics of exposed scents while in the egg, though this needs further research.
Chapter
This chapter discusses the physiology and behavioral responses of aquatic birds to chemical stimulants. It presents comparisons of aquatic versus terrestrial chemical sensations in aquatic birds. It focuses on avian olfaction, homing and foraging by olfactory cues, avian chemesthesis, and avian gustation. It also examines evolutionary changes in avian chemical senses using fossil records of basal ornithurines and extinct Pelecaniformes, and comparative analysis of extant species of Anseriformes, Pelecaniformes, Procellariformes, Gaviiformes, Sphenisciformes, Charadriiformes, and Podicipediformes.
Article
This book focuses on the current understanding of a set of topics in ecological and environmental physiology that are of particular interest to ornithologists, but which also have broad biological relevance. The introductory chapter covers the basic body plan of birds and their still-enigmatic evolutionary history. The focus then shifts to a consideration of the essential components of that most fundamental of avian attributes: the ability to fly. The emphasis is on feather evolution and development, flight energetics and aerodynamics, migration, and as a counterpoint, the curious secondary evolution of flightlessness that has occurred in several lineages. This sets the stage for subsequent chapters, which present specific physiological topics within a strongly ecological and environmental framework. Chapter 2 covers gas exchange and thermal and osmotic balance, together with the central role of body size. Chapter 3 addresses 'classical' life history parameters - male and female reproductive costs, parental care and investment in offspring, and fecundity versus longevity tradeoffs - from an eco-physiological perspective. Chapter 4 offers a comprehensive analysis of feeding and digestive physiology, adaptations to challenging environments (high altitude, deserts, marine habitats, cold), developmental adaptations, and neural specializations (notably those important in foraging, long-distance navigation, and song production). Throughout the book, classical studies are integrated with the latest research findings. Numerous important and intriguing questions await further work, and the book concludes with a discussion of research methods and approaches - emphasizing cutting-edge technology - and a final chapter on future directions that should help point the way forward for both young and senior scientists.
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Physical, chemical and biological processes generate considerable variability in the distribution and abundance of marine organisms. In order to survive and successfully breed, marine predators, among them seabirds, must adjust their movements to changes in the availability of their prey. We studied the foraging behaviour of the northern gannet Morus bassanus in several European colonies to understand how a flexible predator manages environmental variability. We analysed records from miniaturized data loggers (GPS and geolocators) at five spatio-temporal scales: individual, populational, meta-populational, seasonal and inter-annual. These data revealed strong individual plasticity, which allows gannets to modulate the length and duration of their foraging trips and to exploit a panel of memorized feeding areas, for which they anticipate location from a distance. We identified differences in the movements at sea and in home range between colonies during the breeding and the interbreeding seasons. Although gannets were thought to follow a non-oriented dispersion during the interbreeding season; our results showed a clear migratory corridor from Shetland to the West African coast. These results have major implications for a better comprehension of spatial ecology of marine predators facing natural and anthropogenic variability of their environment, as well as for population management, the implementation of marine protected areas, and any conservation measures which depend on spatio-temporal dynamics.
Article
Until recently, species from all but three families of seabirds were known to give extended parental care, provisioning young after fledging. The exceptions were shearwaters, storm-petrels, and penguins. The Gentoo Penguin (Pygoscelis papua) is now known to feed its young after fledging. This paper adds the Galapagos Penguin (Spheniscus mendiculus) to the list, describing five instances of adult provisioning of recently fledged Galapagos Penguin chicks. All feedings were on land and in the afternoon or early evening. Extended parental care is rare in penguins and should occur only if 1) provisioning does not harm adult body condition or conflict with molting, 2) food is available close to the colony, and 3) adults and fledglings return to the nest area after the chicks fledge and before their dispersal from the colony. These requirements suggest it is unlikely that other penguin species commonly feed chicks after they fledge.
Article
We conducted annual counts of moulting Humboldt Penguins roosting on the mainland coast and on offshore islands in north and central Chile during 1999–2008. The census area included the known major breeding colonies in Chile, where many penguins moult, as well as other sites. Population size was relatively stable across years, with an average of 33 384 SD 2 372 (range: 28 642–35 284) penguins counted, but the number of penguins found at any individual site could vary widely. Shifting penguin numbers suggest that penguins tend to aggregate to moult where food is abundant. While many of the major breeding sites are afforded some form of protected status, two sites with sizable penguin populations, Tilgo Island and Pájaros-1 Island, have no official protection. These census results provide a basis upon which future population trends can be compared.
Thesis
This study investigated the potential impacts of several anthropogenic stressors on the movement and survival of African penguins in Algoa Bay, taking into account prey availability and environmental conditions (sea surface temperature and chlorophyll productivity). The primary drive for the study was based on the seismic exploration, which took place in the habitat of the endangered African penguin. The research was also carried out to understand how pelagic fishing and prey availability influence the broader behavioural and mortality aspects of penguins. To achieve this goal, I used monthly beach surveys to assess seabird mortality, admissions of penguins in rehabilitation centres and the monitoring of breeding penguins’ movement at sea through individual GPS tracking. In addition, prey distribution and abundance were monitored with acoustic surveys to assess potential changes in relation anthropogenic stressors. Breeding African penguins did not react dramatically to seismic activities, except on St Croix Island where they changed their foraging direction during the seismic period. There was no evidence of a siginficant increase in African penguin carcasses encountered or strandings along the beaches during the period of seismic activity. However, a sharp increase in encounter rate was recorded soon after seismic operations, which may potentially indicate a delay between the effect of seismic activities on penguin mortality and the encounter of the related carcasses after the operation. However, the impact of seismic surveys on penguins may be long-term rather than short term, and additional studies would be needed to reveal long-term effects of seismic activities, if any. Foraging effort of breeding African penguins increased substantially in the presence of commercial fishing activities within close proximity to the colonies. To a greater extent, at-sea movement patterns and counts of beach cast carcasses were largely influenced by prey availability. Penguins spent more time at sea, traveled longer and covered a larger foraging area during periods of relatvely low pelagic fish abundance. There was also a sharp increase in African penguin mortality during periods of low prey availability in the Bay. However, environmental conditions showed some influence over these interactions. vii Influence of anthropogenic stressors on the behaviour and mortality of the Endangered African penguin For example a red tide event during in period of low prey availability, made it difficult to understand impacts of prey on penguins difficult. Both anthropogenic stressors and environmental conditions influenced African penguins’ behaviour and survival. Due to the worrying trend of African penguins in South Africa for the past few years, all conservation management efforts to increase penguin numbers and limit their mortality are necessary. This study highlights the negative impact of industrial fishing on this Endangered species and the rapid increase in mortality of penguins during times of low prey availability. A network of Marine Protected Areas would certainly increase food availability to African penguins by limiting competition with fisheries, and contribute to increasing the population numbers.
Article
The anatomy and volume of the penguin respiratory system contribute significantly to pulmonary baroprotection, the body O2 store, buoyancy and hence the overall diving physiology of penguins. Therefore, three-dimensional reconstructions from computerized tomographic (CT) scans of live penguins were utilized to measure lung volumes, air sac volumes, tracheobronchial volumes and total body volumes at different inflation pressures in three species with different dive capacities [Adélie (Pygoscelis adeliae), king (Aptenodytes patagonicus) and emperor (A. forsteri) penguins]. Lung volumes scaled to body mass according to published avian allometrics. Air sac volumes at 30 cm H2O (2.94 kPa) inflation pressure, the assumed maximum volume possible prior to deep dives, were two to three times allometric air sac predictions and also two to three times previously determined end-of-dive total air volumes. Although it is unknown whether penguins inhale to such high volumes prior to dives, these values were supported by (a) body density/buoyancy calculations, (b) prior air volume measurements in free-diving ducks and (c) previous suggestions that penguins may exhale air prior to the final portions of deep dives. Based upon air capillary volumes, parabronchial volumes and tracheobronchial volumes estimated from the measured lung/airway volumes and the only available morphometry study of a penguin lung, the presumed maximum air sac volumes resulted in air sac volume to air capillary/parabronchial/tracheobronchial volume ratios that were not large enough to prevent barotrauma to the non-collapsing, rigid air capillaries during the deepest dives of all three species, and during many routine dives of king and emperor penguins. We conclude that volume reduction of airways and lung air spaces, via compression, constriction or blood engorgement, must occur to provide pulmonary baroprotection at depth. It is also possible that relative air capillary and parabronchial volumes are smaller in these deeper-diving species than in the spheniscid penguin of the morphometry study. If penguins do inhale to this maximum air sac volume prior to their deepest dives, the magnitude and distribution of the body O2 store would change considerably. In emperor penguins, total body O2 would increase by 75%, and the respiratory fraction would increase from 33% to 61%. We emphasize that the maximum pre-dive respiratory air volume is still unknown in penguins. However, even lesser increases in air sac volume prior to a dive would still significantly increase the O2 store. More refined evaluations of the respiratory O2 store and baroprotective mechanisms in penguins await further investigation of species-specific lung morphometry, start-of-dive air volumes and body buoyancy, and the possibility of air exhalation during dives. © 2015. Published by The Company of Biologists Ltd.
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Sustainable ecotourism requires careful management of human impacts on wildlife. Contrasting responses to the disturbance caused by ecotourism are observed across taxa and within species, because species and populations can differ in their tolerance to humans. However, the mechanisms by which tolerance develops remain unclear. Penguin colonies are popular tourist attractions. Although ecotourism increases public awareness and generates conservation income, it can also disturb penguins, raising concerns for threatened species such as the African penguin (Spheniscus demersus), whose populations are in rapid decline. We compared the tolerance of African penguins to human disturbance across four colonies with contrasting histories of human exposure. Human approaches invoked the least response at colonies where human exposure was highest, suggesting increased human tolerance with increased exposure. The response to humans close to the nest also decreased more rapidly in highly exposed individuals within colonies. These results were consistent independent of breeding stage, and were repeated among colonies. Because the impacts of human disturbance, including temporary nest desertion, were greatest at the colony with least human exposure, human disturbance of breeding African penguins potentially may be mitigated through increased levels of tolerance to humans, or displacement of shyer individuals, although this could not be assessed in the present study. However, human exposure could significantly increase stress, impair reproduction and even reduce genetic diversity. Consequently, ecotourism must be managed carefully to minimize population level impacts, potentially by facilitating habituation in populations subject to non-threatening human disturbance, and maintaining some areas free of disturbance to allow shy individuals to breed.
Conference Paper
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Coral reefs are frequently used as transient aggregation sites for foraging and spawning by marine fishes. These fishes may use predictable changes in chemical cues associated with reefs as signals to coordinate their aggregations. Dimethyl sulfide (DMS) and its precursor, dimethylsulfoniopropionate (DMSP), are ubiquitous compounds associated with productive areas, preferred sites for foraging and spawning of pelagic species. It is possible that species may recruit to DMS or DMSP (DMS/P) signatures associated with these areas. Here we investigate how temporal variation in the abundance of reef fishes and squid related to changes in DMS/P during a coral spawning event. During 2003, we recorded significant increases in water column DMS/P during a coral spawning event and found that an elevation in DMS/P was paralleled by a surge in numbers of pelagic fishes, Caranx spp., and squid, Loligo roperi, over the reef. The changes in pelagic fish and squid abundance were positively correlated with DMS/P, suggesting that these animals may cue to the release of specific compounds during spawning. These results, coupled with other recent studies, provide further evidence that DMS/P may be used by fishes and squid to coordinate their aggregations over reefs. Introduction Dimethyl sulfide (DMS) has been studied intensively by atmospheric and process-oriented oceanographers for its role in global climate, marine sulfur cycles and phytoplankton physiology (e.g., Curran and Jones 2000; Kiene et al. 2000). Dimethylsulfoniopropionate (DMSP) is a water-soluble osmolyte produced by species of marine phototrophic algae and is the major precursor of the volatile compound, dimethyl sulfide (DMS). DMSP is converted to DMS and acrylic acid by bacterial and algal enzymatic degradation (Kiene et al. 2000) and this metabolic conversion is accelerated during grazing by zooplankton (Dacey and Wakeham 1986; Daly and DiTullio 1996). Since the release of DMS and DMSP can be a by-product of zooplankton feeding (Cantin et al. 1996), its patchy distribution in the marine environment may reflect grazing rate (Kwint and Kramer 1996; Wolfe and Steinke 1996). Further, Hill and Dacey (2006) found that dissolved DMSP is released into the water immediately after foraging by planktivorous fishes. Coral reefs are significant production sites for DMS and DMSP (Broadbent and Jones 2004). Reefs appear to produce DMSP in part through interactions between coral and their symbiotic zooxanthellae (Hill et al. 1995; Van Alstyne et al. 2006). Zooxanthellae taken from Acropora coral tissues from the Great Barrier Reef produce up to 285 fmol DMSP per cultured cell and up to 3831 fmol per cell in corals (Broadbent et al. 2002). Further, Broadbent (1997) reported an increase in water column DMS and DMSP the day after a mass coral spawning and attributed it to the corals' release of mucus and eggs containing zooxanthellae. We are only beginning to understand the roles of DMSP and DMS as signal molecules in marine and terrestrial ecosystems (see Nevitt et al. 1995; Zimmer-Faust et al. 1996; Steinke et al. 2006; DeBose et al. 2006, 2007, 2008). High DMS and DMSP concentrations over productive marine areas can be long-lasting (hours to days; Ledyard and Dacey 1996) and thus, provide predictable cues that may be used by organisms to locate habitat. For instance, frontal zones are productive areas where seabirds (Nevitt 2000), Humboldt penguins (see Culik 2001), and basking sharks (Sims and Quayle 1998) forage on dense plankton patches. Nevitt (2000) has implicated air-borne DMS as part of an 'olfactory landscape', which can be detected by pelagic Procellariiform seabirds in search of productive areas for foraging. Humboldt penguins increase their anticipatory activity in the presence of DMS, suggesting that penguins could use DMS as a foraging cue as well (Culik 2001). Similarly, Sims and Quayle (1998) suggest that basking sharks might use DMS to locate dense patches of plankton along frontal zones.
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The Humboldt Penguin Spheniscus humboldti is an endangered species whose population is decreasing over its whole distributional range. In support of conservation efforts, systematic studies are being conducted on the ecology and behaviour of these birds at sea. Time-depth recorders were used to investigate the foraging behaviour of Humboldt Penguins at Isla Pan de Azúcar (26°S, 72°W), northern Chile, during the breeding seasons of 1994/95 and 1995/96. A four-channel logger (MK6, Wildlife Telemetry) equipped with speed, depth, temperature and light-intensity sensors was used to obtain information from 20 foraging trips of 12 penguins, amounting to a total of 301 hours of swimming consisting of 11 011 dives. Birds departed from the colony between 06h00 and 09h00 and returned mainly between 15h00 and 23h00. Distance travelled was strongly correlated with total time spent at sea. Maximum dive depth was 53 m around mid-day when light intensity was maximal. At night maximum depth attained was 12 m. Maximum dive depth was positively correlated with dive duration (r = 0.80), as well as with descent and ascent angle (r = 0.78), and descent and ascent rate (r = 0.86). Dives to between 0.5 and 3 m were interpreted as travelling dives and had a mean depth of 1.6 m. All dives deeper than 3 m were regarded as foraging dives with a mean depth of 11.5 m. Mean dive durations during travelling and foraging were 18.4 s and 47.9 s, respectively. Mean swim speed during travelling was 1.7 m.s-1. Overall speed during foraging dives (descent, bottom and ascent) was 1.9 m.s-1.
Article
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With the development of new technologies such as satellite transmitters (Davis & Miller 1992), data-loggers (Wilson et al. 1993) and radio-telemetry (Heath & Randall 1989), the cap- ture of live specimens prior to the attachment of such equip- ment plays a very important role. It has been shown that the attachment of any device may have a deleterious effect on the normal behaviour of wild birds (Wilson & Culik 1992), but this may be at least partially due to the capture techniques em- ployed.Recently, we started ecophysiological studies on the Humboldt Penguin Spheniscus humboldti at sea. For that purpose we employ data-loggers that are able to record information on swimming speed, foraging range and dive depth. Before using these instruments we carried out an experiment with four adult Humboldt Penguins to which dummy instruments were attached in order to assess: 1) responses of the penguins to Ketamine hydrochloride; 2) the best dose of Ketamine hydro- chloride for Humboldt Penguins; and 3) responses of the pen- guins to capture, manipulation, and attachment of the dummy instruments. Following this, we began our study with authen- tic instruments. In all cases we registered the dose of the anaesthetic and the symptoms associated with it. In this con- tribution we report the methods used to inject the anaesthetic and the responses of the penguins.
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The Humboldt Penguin (Spheniscus humboldti) has been reported as declining along its distributional range and has recently been classified as vulnerable. The actual size of the Humboldt Penguin population is still unknown, and a complete population assessment is required. Here we present a study combining both counts of molting birds on land and counts of birds at sea during the molting period. We conducted our study in the Coquimbo Region, Northern Chile, and found 7,619 birds on land and 2,700 at sea, adding up to a total of about 10,300 Humboldt Penguins during the molting season (February 1999). Since these numbers are much higher than all other recent estimates, we emphasize that assessment on land and at sea need to be combined to provide more reliable estimates.
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Humboldt Spheniscus humboldti and Magellanic S. magellanicus penguins exhibit a zone of sympatry along the west coast of South America. The authors examined aspects of their foraging ecologies at four sites (three in the zone of sympatry) along the Chilean coast between 29° and 53°S and found that inter-site differences were more pronounced than inter-specific differences. In contrast, the two species differed in their breeding seasons.
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As one of the elements for a model on the food requirements of Humboldt penguins Spheniscus humboldti we determined, via gas respirometry, metabolic rates while swimming and resting in water. During rest in water at 19 degrees C Humboldt penguins (mean body mass 3.6 kg) required 5.95 W kg(-1). This corresponds to a thermal conductance in water of 0.2975 W (kg degrees C)(-1) (at T-a 19 degrees C and assuming a Tb Of 39 degrees C). When swimming in a 20 m long channel, metabolism rose from 8 W kg(-1) at a speed of 0.6 ms(-1) to 23.1 W kg(-1) at 2.2 m s(-1). Transport costs (the cost to move 1 kg of body mass over a distance of 1 m) reached a minimum at 1.4 ms(-1) with 8.1 J (kg m)(-1), which corresponds to 0.89 J (Nm)(-1). We corrected for acceleration and deceleration in the channel to determine transport costs of free-ranging Humboldt penguins travelling at sea, which were calculated as 7 J (kg m)(-1) (0.71 J [Nm](-1)), at 1.7 m s(-1). Birds feeding chicks need to balance the costs of either (1) returning to the breeding island for the night and travelling back to the feeding grounds in the morning or (2) incurring increased thermoregulatory costs associated with resting at sea overnight. Simple calculations show that at water temperatures of 19 degrees C we expect Humboldt penguins to show a tendency to remain at sea overnight if foraging areas are >4 km from their island. In colder waters (12 degrees C), this distance increases to >9 km. Using previously published data on at-sea activity of Humboldt penguins, we found that foraging costs during chick rearing amount to 340 g anchovies d(-1). Finally, we present a general model to convert Humboldt penguin activity data at sea to food requirements.
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VHF telemetry was used in November and December 1995 on 8 Humboldt penguins Spheniscus humboldti breeding at Pan de Azucar Island (26 degrees S, 70 degrees W), Northern Chile, to determine at-sea behaviour of the birds. We obtained 2710 locations, 90% of which were within a radius of 20 km around the island. Mean travelling speed of the birds was 0.92 m s(-1) and speed distribution showed peaks at 1.6 and 3 m s(-1). Penguins travelling between foraging areas remained submerged for an average of 8.4 s between surfacings, whereas foraging dives lasted on average 61 s. The analysis of 79 complete foraging trips showed that tracks deviated from a straight course, and range (maximum distance from island) was only 0.37 times total horizontal distance swum. Birds did not forage synchronously or in the same foraging areas. However, foraging ranges were correlated between birds, indicating similar search strategies during periods of low food availability. The results obtained here via VHF telemetry agreed well with those of previous studies employing satellite transmitters and data loggers.
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Line transects from boats were conducted during 1984 and 1985 to determine African Penguin (Speniscus demersus) distribution in the South African Cape waters. Range limits for breeding birds were derived from information on penguin travelling speeds and durations of foraging trips. Over 50% of all penguins considered to be non-breeding occurred within 20 km of the coast whilst over 50% of all breeding birds occurred within 3 km of the coast. Penguin density decreased with increasing distance offshore. The most frequently encountered penguin group size was one with larger groups decreasing in incidence according to a power curve decay. There was no difference in the frequency of occurrence of different group sizes between breeding and non-breeding penguins, nor did group size distribution change with distance offshore. Data on African Penguin distribution at sea collected in 1984 and 1985 was not discernably different to equivalent data collected between 1954 and 1974. The composition of penguin group size was also the same during both periods.
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Few studies of diving predators have explicitly addressed the 3-dimensional nature of interactions between predators and prey at the spatial and temporal scales relevant to an individual predator's search behavior. Here, we present a new method for examining such interactions using the results from an acoustic survey of krill availability to foraging penguins. Analyses of fine-scale krill distributions within a 1852 x 1852 x 50 m volume of ocean revealed substantial prey patchiness in all dimensions. Our survey detected the presence of at least 6 krill aggregations in the survey area. The surface distribution of penguins was associated with the edges of these aggregations and was nonrandomly associated with krill densities above 0.1 krill m(-3) in the 30 to 40 m depth layer. The latter association was masked when krill abundance was integrated over the entire water column. Given that mean daytime dive depths for chinstrap penguins fall between 30 and 40 m, our data suggest penguins may fail to detect or choose to pass by shallow, denser prey aggregations and successfully forage on deeper, more homogeneously distributed krill offering higher encounter probabilities per unit volume searched. These findings reveal biologically important features of prey patchiness that cannot be addressed within the limitations of a primarily 2-dimensional analysis of predator-prey distributions. We emphasize that if we hope to gain a predictive understanding of the foraging behavior of diving predators, then we must consider fine-scale, 3-dimensional patterns of prey patchiness when assessing the availability of prey to diving predators.
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MANY Procellariiform seabirds make their living flying over vast expanses of seemingly featureless ocean waters in search of food. The secret of their success is a mystery, but an ability to hunt by smell has long been suspected1–7. Here we present experimental evidence that Procellariiform seabirds can use a naturally occurring scented compound, dimethyl sulphide, as an orientation cue. Dimethyl sulphide has been studied intensely for its role in regulating global climate8–11 and is produced by phytoplankton in response to zooplankton grazing12. Zooplankton, including Antarctic krill (Euphamia super ha)13, are in turn eaten by seabirds and other animals14. Results from controlled behavioural experiments performed at sea show that many Procellariiforms can detect dimethyl sulphide, and that some species (for example, storm petrels) are highly attracted to it. To our knowledge, this constitutes the first evidence that dimethyl sulphide is part of the natural olfactory landscape overlying the southern oceans.
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The relationships between the foraging strategy of seabirds, hydrographic features and food availability are poorly understood. We investigated the movements at sea, time spent per oceanic sector, food intake, and diet of king penguins Aptenodytes patagonicus in the Crozet Islands (Southern Indian Ocean) during summer, as a function of the position of major frontal zones. Fifteen trips at sea were monitored using satellite transmitters over 3 austral summers (1992 to 1994). During each season, satellite transmitters were used in conjunction with stomach temperature recorders in order to investigate feeding activity. The at-sea distribution of king penguins was closely related to the localisation of major hydrographic frontal systems. Intense prospecting areas were observed mainly in zones corresponding to the northern limit of the Polar Front (50°to 51°S), southern limit of the Sub-Antarctic Front (44.50°to 45°S), and a zone between 47°and 48°S. During trips directed south, 2 distinct phases based on travelling speed were detected. The myctophids Electrona carlsbergi, Krefftichtys anderssoni and Protomyctophum tenisoni dominated the diet. The estimated average amount of food ingested per day at sea was 2.4 kg. Between 17 and 64 kg of food was captured during 7 to 25 d at sea. Approximately 80% of the food intake occurred during the first phase of the trip. Food intake was related to trip duration and relative amount of time spent in particular oceanic sectors. The sections 47°to 48°S and 48.5°to 50.50°S appeared particularly favorable for food intake, the latter coinciding with the northern limit of the Polar Front. King penguins fed intensively on several distinct patches when traveling towards the Polar Front. The foraging range seems to be related to the foraging success during the first phase of the trip. The foraging strategy of king penguins during the summer favors displacements toward frontal zones where food availability is optimal.
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During the El Niño of 1982/1983, the Humboldt penguin population diminished dramatically in the whole distributional area of the species. Recovery of the population was slow since 1983 and it has been suggested that large numbers of Humboldt penguins die at sea, entangled in nets, or starve to death, even during non-“El Niño” years. We were able to determine for the first time, how Humboldt penguins on Pan de Azúcar Island (26°S; 72°W) utilize their marine habitat and where their feeding areas lie. For this purpose we employed two streamlined Argos satellite transmitters during the 1994/1995 and 1995/1996 breeding seasons, respectively. Mean travelling speed of Humboldt penguins during foraging trips was 0.94 m s−1 and 50% of bird positions were located within 5 km of the island (90% within 35 km). Total area covered by Humboldt penguins foraging from Pan de Azúcar Island was 12 255␣km2. Satellite transmitters also recorded dive duration; penguins spent on average 7.8 to 9 h diving per foraging day but showed no preferences for particular feeding areas. Mean daily dive durations (4-d mean) recorded during the 1994/1995 breeding season were positively correlated between birds. Significant correlation between dive duration and sea surface temperature anomalies and negative correlation between dive duration and fishery landings at nearby Caldera harbour indicate that the 1994/1995 increase in foraging effort was a response to deteriorating prey availability. Sea surface temperatures during the 1995/1996 breeding season were colder than average, and we observed no trends in bird diving activities.
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Until recently, the endangered Humboldt penguin was considered a sedentary bird, which remained near its breeding colonies throughout the year. In this pilot study we used five satellite transmitters on Humboldt penguins during the austral winter and were able to track one bird from Pan de Azcar Island (2609S, 7040W), Northern Chile to Iquique (2012S, 7007W), a distance of 640 km, between May 24 and June 26, 1996. While a 35 km protection zone around breeding islands might be helpful to prevent competition of penguins with fisheries during the summer months, this might not improve the survival of migrating birds in the winter. Further studies are required to determine the extent of migration and to confirm the recorded travelling route and landing locations in order to detect possible threats to Humboldt penguins from fishing and other industries throughout the year.Whrend noch vor wenigen Jahrzehnten Millionen Humboldtpinguine die Ksten Perus und Chiles bevlkerten, wird die Art heute als gefhrdet eingestuft. Die Fischerei stellt die grte Bedrohung fr diese Tierart dar, deren Gesamtbestand sich nach letzten Schtzungen nur noch auf 10 000 Individuen beluft. Wir setzten im Sdherbst 1996 fnf Argos-Satellitensender ein, um festzustellen, ob Humboldtpinguine des Naturschutzgebietes Pan de Azcar (2609S) im Winter ortstreu bleiben oder saisonale Wanderungen durchfhren. Whrend sich vier der Vgel im Untersuchungszeitraum (18–74 Tage) nicht weiter als 87 km von ihrer Brutinsel entfernten, wanderte ein Vogel im Juni 1996 nach Norden bis vor die Stadt Iquique (20 12S, 640 km vom Ausgangspunkt entfernt). Obwohl die in einer frheren Studie ermittelte Gre eines marinen Schutzgebietes von 35 km Durchmesser rund um die Brutinsel in den Sommermonaten ausreichend sein mag, belegen die neuen Ergebnisse, da weitere Untersuchungen ber das Wanderverhalten der Humboldtpinguine als Grundlage fr einen effektiven Artenschutz unerllich sind.
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Core temperature was determined in two king penguins living in the wild at Ile de la Possession, Crozel Archipelago, using implantable four-channel temperature loggers. Core temperatures derived from bird no. 1 (sensor placed under the sternum, in the vicinity of the liver and upper stomach) were closely correlated with diving activity (as determined by an external light recorder), and ranged from 38.3°C, (on land) to a minimum of 37.2°C during a dive. Core temperatures measured in bird no. 2 showed that temperatures near the heart were generally 1°C lower than those under the sternum or in the lower abdomen. Core temperatures declined continuously during dives (by 0.8, 1.2 and 2.7°C in the lower abdomen, under the sternum and near the heart, respectively) and showed precipitous drops to 35°C, probably associated with ingestion of food. Temperatures measured near the heart fluctuated over a period of 288 s, corresponding to the duration (from the literature) of the surface/dive cycle. The relevance of these findings with respect to diving physiology, blood perfusion of tissues, tissue metabolism and aerobic dive limits is discussed.
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Experimental findings obtained in recent years make it possible to recognize and distinguish the most relevant components determining homing flights of displaced pigeons. Conclusions deduced from these experiments, more or less compelling or tentative, are presented in the form of seven theses, supplemented by several subtheses along with reference to empirical data. The principal theses are as follows. (1) Passively displaced pigeons find the way home by using location-dependent signals and not by path integration based on recording of motion. Pigeons are able to home, even from unfamiliar areas, without access to potentially useful information during transport to the release site. (2) Home-related orientation of pigeons in unfamiliar areas requires positional information acquired olfactorily from atmospheric trace gases. Empirically deduced details of olfactory navigation are enumerated (connection with winds and the sun, inaccuracy, spatial range, time course of sampling and memorizing spatial information, etc.). The critical gap in our knowledge, i.e. the nature and spatio-temporal distribution of the substances involved, is provisionally filled by speculation. (3) In familiar areas, known from previous flights, the visual landscape is used additionally to find the way home. (4) Initial orientation of pigeons does not exclusively reflect home-related navigation but includes components independent of the position with respect to home. Observed bearings are co-determined by a general preference for a certain compass direction and by distracting features of the nearby landscape. (5) Proportions among components controlling initial orientation according to theses 2-4 are highly variable depending on local, temporal and experimental conditions and on the life histories of the pigeons. This complexity greatly restricts recognition of the navigationally relevant components of behaviour at a given release site. (6) Sensory inputs, being neither olfactory nor visual, do not substantially contribute to determining the current position with respect to home. This thesis need not be definitive, but at present no contradicting evidence is available. (7) Pigeon homing is a model case of bird homing in general. Experiments with other species support this thesis. So far, there is no reason to assume that wild birds apply mechanisms fundamentally different from those of pigeons to find the way home.
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Wind tunnel and water tank experiments were carried out on a penguin model in order to optimise the shape and attachment of a back-mounted datalogger. Device-induced turbulence was minimised when the unit was placed in the most caudal position. Drag was further reduced by shaping the device to match the body contour. The hydrodynamic resistance of the package could be reduced by 65 % compared with an earlier unit. These results are discussed together with results from new studies on kinematics and energetics of underwater swimming of live instrumented penguins.
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The hunting behavior of a marine mammal was studied beneath the Antarctic fast ice with an animal-borne video system and data recorder. Weddell seals stalked large Antarctic cod and the smaller subice fish Pagothenia borchgrevinki, often with the under-ice surface for backlighting, which implies that vision is important for hunting. They approached to within centimeters of cod without startling the fish. Seals flushed P. borchgrevinki by blowing air into subice crevices or pursued them into the platelet ice. These observations highlight the broad range of insights that are possible with simultaneous recordings of video, audio, three-dimensional dive paths, and locomotor effort.
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We satellite-tracked five Humboldt penguins during the strong 1997/98 El Niño Southern Oscillation (ENSO) from their breeding island Pan de Azúcar (26 degrees 09'S, 70 degrees 40'W) in Northern Chile and related their activities at sea to satellite-derived information on sea surface temperature (SST), sea surface temperature anomaly (SSTA), wind direction and speed, chlorophyll a concentrations and statistical data on fishery landings. We found that Humboldt penguins migrated by up to 895 km as marine productivity decreased. The total daily dive duration was highly correlated with SSTA, ranging from 3.1 to 12.5 h when the water was at its warmest (+4 degrees C). Birds travelled between 2 and 116 km every day, travelling further when SSTA was highest. Diving depths (maximum 54 m), however, were not increased with respect to previous years. Two penguins migrated south and, independently of each other, located an area of high chlorophyll a concentration 150 km off the coast. Humboldt penguins seem to use day length, temperature gradients, wind direction and olfaction to adapt to changing environmental conditions and to find suitable feeding grounds. This makes Humboldt penguins biological in situ detectors of highly productive marine areas, with a potential use in the verification of trends detected by remote sensors on board satellites.
Article
Mortality of Humboldt Penguins Spheniscus humboldti drowned in gill nets is documented for the Valparaiso Region, central Chile, based on sampling and reports from local fishermen. Between 1991 and 1996 at least 605 Humboldt Penguins died in gill nets set for 'corvina' Cilus gilberti, an average of 120 birds per year. Lesser numbers of other seabirds, including Magellanic Penguins S. magellanicus, Red-legged Cormorants Phalacrocorax gaimardi and Guanay Cormorants P. bougainvillii were killed. Drownings occur mainly during winter (June to August), reducing the population prior to the spring breeding season. Drowning kills adults from the two major colonies of Humboldt Penguins in central Chile, Cachagua and Pájaro Niño. Entanglement of Humboldt Penguins in fishing nets has been reported for other sites in Chile and Perú, suggesting similar mortality along most of the species' range.
Article
In conjunction with the Third International Penguin Conference, a Penguin Conservation Assessment and Management Plan (CAMP) workshop was conducted in September 1996. Facilitated by the Conservation Breeding Specialist Group of the IUCN, this process involved more than 75 experts from 40 institutions working together to review the current information on distribution, threats and status of 20 penguin taxa. Based on the compiled data, IUCN Red List Categories of Threat were assigned; 12 of the 20 taxa were listed as threatened, an increase from the five taxa assessed as threatened in the 1996 IUCN Red Data Book. This paper outlines the causes for concern for the various penguin taxa and describes the criteria used to make these assessments. It also summarises urgent research and management recommendations made by the workshop participants. It is the responsibility of these participants, as well as all penguin researchers, to call attention to the grave situation facing penguins through the media and public education. By aiding the pooling of expertise and information, and helping to set new directions for future conservation efforts, the CAMP process assists these efforts.
Chapter
The impact of EN on pinnipeds in northern Chile was quite different from that in Peru (Majluf, this Vol.) and in the Galapagos (Trillmich and Dellinger, this Vol.), thus demonstrating that the response of populations varied strongly with latitude.
Article
Penguins are often considered to be as ecologically and behaviourally homogenous as their morphology. Their structural morphology and associated physiological adaptations are governed by the demands of operating as flightless, subsurface marine predators. However, within the very strict constraints of this lifeform, penguins show considerable ecological and behavioural heterogeneity, although some of this undoubtedly relates to the range of latitudes and biotopes in which penguins breed. In this paper we: (i) briefly summarise and review some of the main features of the breeding biology, ecology and demography of penguins; (ii) identify consistent patterns across species in the grouping of these features - and highlight anomalies; (iii) suggest explanations/hypotheses for some of the potential links between ecology, behaviour and demography within these groupings; (iv) investigate six topics containing potential paradoxes, namely: migration, fasting, mate fidelity, brood reduction, demography and duration of breeding seasons. We conclude that in many biological and ecological traits penguins can be divided into two groups: (i) resident species, feeding inshore with short fasts ashore, breeding at an early age and having low divorce rates, and; (ii) migrant species, feeding offshore with long fasts ashore, breeding at older ages and having higher divorce rates. The placement of Magellanic Spheniscus magellanicus and Gentoo Pygoscelis papua Penguins in opposite groups to their congeners is particularly intriguing. We suggest that trade-offs between the year-round abundance and predictability of prey and the latitudinally-influenced time available for breeding are important determinants of these patterns. Considerably improved basic biological and ecological data on penguins and careful testing of explicit hypotheses will be required to investigate further both the suggested patterns and the remaining paradoxes.
Chapter
The South American fur seal (Arctocephalus australis) and the South American sea lion (Otaria byronia) are the only two species of pinniped exploiting the rich Peruvian upwelling system. Both, like most other pelagic feeding vertebrates in Peru, feed largely on anchovy (Engraulis ringens), a small clupeid fish which previous to 1973 occurred in abundance in this system (Idyll 1973). Because of the economic importance of anchovy to the Peruvian fishing industry, the biology of anchovy and the effects of El Niño (EN) on its distribution and abundance have been relatively well documented (Glantz and Thompson 1981; Cushing 1982; Pauly and Tsukayama 1987) and thus it is possible to understand how EN events affect the seals’ prey availability. Here, I shall compare the foraging behaviour, diet, pup growth and mortality of the fur seals and sea lions in Peru under EN and non-EN conditions and examine whether the differences can be explained by the changes in anchovy availability known to take place during ENs. Greater emphasis will be placed on the fur seals because there is only limited information on sea lions in Peru.
Article
Mammals birds reptiles fish invertebrates wildlife management pollution hibernation terrestrial animals marine animals freshwater animals estuaries wetlands environmental physiology territories social behaviour home ranges foraging predation orientation and navigation homing statistical analysis satellite tracking VHF radio UHF and microwaves radar underwater acoustics infra-red lasers.
Article
Over a period of four years, nineteen adult Humboldt Penguins (Spheniscus humboldti) banded at a colony on Islote Pajaro Nino near Algarrobo, Chile were recovered or sighted at locations away from the colony. Eighteen birds were found dead, and one bird was sighted alive at another breeding colony. Eight of the penguins were found entangled in fishing nets, while the circumstances of death for the other ten birds were unknown. Dead birds were found three km to 592 km from Algarrobo. The live bird was sighted approximately 88 km north. These data indicate that adult Humboldt Penguins may visit other breeding colonies and corroborate previously published data that Humboldt Penguins may travel long distances from their breeding colony Our data also indicate that accidental drowning in fishing nets is a cause of mortality in this species.
Article
During a cruise over the Atlantic from 40{degree}S to 50{degree}N in March-April 1987 the concentrations of dimethylsulfide (DMS) in the ocean and atmosphere were measured as well as the distribution of its precursor, dimethylsulfoniopropionate (DMSP), and of several biological parameters such as chlorophyllm, phytoplankton species, and adenosine-5-triphosphate (ATP) in the surface water. The DMS concentration varied in the range 0.2-2 nmol DMS{sup {minus}1} (surface water) and 0.05-3 nmol DMS m{sup {minus}3} (atmosphere) in the region of the remote tropical and subtropical Atlantic and increased to 2-10 nmol DMS{sup {minus}1} (surface water) and 1-8 nmol DMS m{sup {minus}3} (atmosphere) north of 40{degree}N and in the English Channel. Based on these results the mean flux of DMS from the Atlantic to the atmosphere is estimated to be 4-4.65 nmol DMS m{sup {minus}2} min{sup {minus}1}. A moderate diurnal variation of atmospheric DMS was found with a minimum during daytime. The DMS concentration in seawater correlated well with the concentration of DMSP and showed a similar trend to ATP, chlorophyll, and some phytoplankton species.
Article
Foraging adult southern elephant seals, Mirounga leonina, from Penı́nsula Valdés, Argentina, dive continuously while travelling across the continental shelf towards deep waters of the SW Atlantic. This study attempted to identify distinct ocean environments encountered by these seals during foraging migrations based on bathymetric and water temperature profiles, and to interpret these profiles in terms of mixing and systems of currents. Depth and water temperature were obtained with data loggers carried by 14 diving adult animals during spring (October–December) and summer (February–March) months. Dive depths allowed us to unmistakably differentiate extensive areas of the SW Atlantic: the Patagonian shelf, shelf slope and open waters of the Argentine Basin. Water temperature profiles added further details to the latter general oceanographic areas, and could be related to large-scale oceanographic processes that led to different water column structures. Temperature data reflected the mixing effects of winds and tides in coastal waters, the formation of a thermocline in mid-shelf areas, the northward flow of the sub-antartic Malvinas Current at the edge of the shelf, and the effect of the subtropical Brazil Current further east over deep off-shelf waters. Some of these distinct areas are known for their enhanced primary production associated with frontal systems. The study shows that elephant seals could be useful, low-cost platforms to obtain oceanographic data. Studies that require extensive sampling of physical variables in large areas over long periods of time would benefit from this approach, pending on more precise and frequent locations of animals at sea.
Article
The Humboldt penguin Spheniscus humboldti is endemic to the Peruvian Current which flows northward along the coast of Chile and Peru. This species has greatly diminished from its former abundance.The coast of Peru is characterised by high biological productivity which concentrates fish such as the anchovy Engraulis ringens, the main prey item of marine predators including seabirds. In years of the abnormal oceanographic conditions of El Nino, the schools of anchovies become unavailable to the seabirds and they disperse in search of food. Massive mortality, especially of juveniles, results and there is nest desertation and lack of reproduction.This paper describes the effects of the 1982–1983 El Nino on Humboldt penguin colonies in Peru. There has been an overall population decline of 65% and the surviving population in 1984 was estimated to be between 2100 and 3000 adults. Although El Nino is a periodic event and the Humboldt penguin has evolved to adapt to such unpredictable changes, the environment has now been altered by man. Under these circumstances, the 1982–1983 El Nino has contributed to placing this species in a critical position.
Article
THE emperor penguin (Aptenodytes forsteri), which feeds only at sea, is restricted to the higher latitudes of the antarctic sea-ice habitat1–3. It breeds on the winter fast ice when temperatures are−30 °C and high winds are frequent3. Assuming entirely the task of incubating the single egg, the male fasts for about 120 days in the most severe conditions. When it is relieved by the female around hatching time, the distance between the colony and the open sea may be 100km or more4,5, but where emperors go to forage at that time or during the summer is unknown. The polynias are areas of open water in sea-ice and during winter, with the under-ice habitats at any time of the year, they are among the most difficult of all Antarctic areas to sample. Here we monitor by satellite the routes taken by emperor penguins for foraging and compare them with satellite images of sea-ice. Winter birds walking over fast ice travelled up to 296 km to feed in polynias, whereas those swimming in light pack-ice travelled as far as 895km from the breeding colony. One record of diving showed that although most dives are to mid-water depths, some are near the bottom. Obtaining such detailed information on foraging in emperor penguins means that this bird now offers a unique opportunity to investigate the Antarctic sea-ice habitat.
Article
How do pinnipeds orientate themselves under water? As most pinniped species feed in conditions under which visibility is drastically reduced, for example at night, at great depths or in murky waters, it has been particularly unclear how they succeed in finding food. Here we show that harbour seals (Phoca vitulina) can use their whiskers to detect minute water movements. The high sensitivity of this sensory system should allow a seal to gain hydrodynamic information resulting from movements of other aquatic animals, such as prey, predators or conspecifics.
Article
Speed/distance meters were deployed on adeliée, gentoo and chinstrap penguins Pygoscelis adeliae, P. papua and P. antarctica, breeding near Anvers Island, Antarctica. Underwater speeds and distances travelled were interspecifically very similar (means of ca. 7–8 km h-1 and 15–45 km, respectively). These results are compared with published data on penguin behaviour at sea obtained by using identical methodology. A simple model, based on penguin activity at sea data, is developed to derive range limits for penguins. Derived range limits are substantially lower than previous estimates but accord well with distributional data obtained by transects.
Article
Female Adlie penguins (Pygoscelis adeliae) that take too long on their first post-laying foraging trip are a major cause of breeding failure, but in the ice-filled waters of Antarctica, determining where they go and why they are away so long has proved difficult. Here we describe the first successful attempt to track penguins at sea using satellite telemetry. Four females foraged in different locations, dispelling the notion of a common feeding ground. They moved up to 272 km from the rookery and covered from 551 to 1,121 km on their trips, swimming at minimum average speeds around 1.2 m/s. The birds were most likely to be in the water between 0630 and 1430 when light intensity, important for a visual predator, was greatest. Carrying the transmitters reduced rates of fat deposition (weight gain), increasing the duration of foraging trips of females, and suggested that they may forage until their fat depots reach a minimum threshold level. This has two implications: (i) durations of these postlaying foraging trips could potentially be used as an indicator of krill abundance (Euphausia sp), the almost exclusive food of Adlie penguins during this period, and (ii) any reduction in krill stocks caused by harvesting could increase foraging trip durations with a concomitant increase mi breeding failures.
Article
Many researchers use external recording or transmitting devices to elucidate the marine ecology of fish, mammals and birds. Deleterious effects of these instruments on the parameters researchers wish to measure are hardly ever discussed in the literature. Research has shown that, in penguins, volume and cross-sectional area of instruments negatively correlate with swimming speed. dive depth and breeding success, and that device colour affects bird behaviour. Here, a large (200 g, cross-sectional area 2100 mm2) streamlined device was attached to the lower back of Adlie penguins (Pygoscelis adeliae on Ardley Island, South Shetland Island in 1992) and its effects on bird swimming speed and energetics were measured in a water canal in Antarctica. Although the device was 10.5% of penguin cross-sectional area, swimming speed was reduced by only 8.3% and mean power input increased by only 5.6% while swimming. Although our streamlined device was five times more voluminous than one of our older units, the effect on swimming energetics could be reduced by 87%.
Article
Adélie penguins (Pygoscelis adeliae), after breeding in Antarctica during the austral summer, undergo a winter migration before returning to the breeding grounds 8 months later. It is the major source of adult mortality, with about a quarter of them not returning. Here we describe the first attempt to track the winter migration of Adélie penguins using satellite telemetry. Transmitters were attached to two penguins on 16 February 1991 after their post-breeding moult at Cape Bird, Ross Island, Antarctica. Transmissions were received from one penguin (bird #1) for 4.4 months, during which time it travelled 2792.6 km from the rookery (nearly 1500 km straight-line distance). Transmissions were received from the other penguin (bird #2) for 2.5 months during which time it followed a path remarkably similar to that of bird #1. The penguins travelled northwards up the coast of Victoria Land, keeping within 100 km of the coast, rounding Cape Adare soon after 29 March and were midway between the Balleny Islands and the Antarctic coast on 3 May. Thereafter, the record from bird #1 shows that it travelled further westwards until, when opposite the Mastusevich Glacier Tongue of the Mastusevich Glacier, it turned due north and moved away from the coast. By 29 June, when transmissions ended, its progression had slowed and it was northwest of the Balleny Islands near a zone where pack ice covered 75% of the surface of the sea. Two novel points that arise from this study are: (1) that Adélie penguins from Cape Bird undergo winter migrations of not less than 5000 km, and (2) that they may be travelling to common overwinter feeding grounds.
Article
The drastic changes in the abiotic environment caused by El Niño (EN) 1982–83 led to marked repercussions in the fauna and flora of the marine ecosystem, including pelagic and benthic marine subsystems and the seashore. Some of them were of a negative, others were of a positive nature. Mass mortalities of some species contrasted with enormous proliferations of others. Many species emigrated during EN from their traditional, cool upwelling areas, which had been converted to tropical or unusually warm conditions. Some moved towards deeper water, others poleward where conditions resembled those in their former habitat. Growth, body condition, reproduction and adult survival of some species were diminished. Also, changes in growth and survival of early life history stages affected recruitment of some species years later. At the same time dispersal stages of warm water species were transported south-/northward, and juveniles and adults actively invaded unusual areas. The biological effects of EN 1982–83 have been summarized in various conference volumes (Arntz et al. 1985b; CONCYTEC 1985; IFOP 1985; Robinson and del Pino 1985; Wooster and Fluharty 1985; IOC 1986; AGU 1987) and a number of reviews (Barber and Chávez 1983, 1986; Arntz 1984, 1986; McGowan 1984; Barber et al. 1985; Mysak 1986; Pearcy and Schoener 1987; Alvial 1988; Arntz and Fahrbach 1991).
Article
During the years 1982–84 different pinniped populations along the Pacific coasts of the Americas were heavily affected by climatic anomalies over a wide range of latitudes, extending from Alaska in the north to the south of Chile. These anomalies can be related to El Niño (EN), a climatological phenomenon characterized by anomalous conditions in the atmosphere and the ocean. It appears in a somewhat regular time sequence in the tropical Pacific, extends, however, less intensively to the mid-latitudes and beyond. During EN, anomalously warm water appears along the coast of Ecuador and Peru. As an example we show the deviation of the sea surface temperature from the long-term mean at Puerto Chicama (Fig. 1). The magnitude of this positive sea surface temperature (SST) anomaly can be used to classify the intensity of an EN.
Olfactorial navigation in Humboldt pen-guins? Christian-Albrechts-Universität Kiel, M. Sc. Thesis. Hays, C. 1986. Effects of the El Niño on Humboldt penguin colonies in Perú
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Hagemann, S. 2000. Olfactorial navigation in Humboldt pen-guins? Christian-Albrechts-Universität Kiel, M. Sc. Thesis. Hays, C. 1986. Effects of the El Niño on Humboldt penguin colonies in Perú. Biol. Conserv. 36: 169–180.
Foraging ecology. In: The penguins
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Status of the Humboldt penguin in Chile following the 1982-83 El Niño
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Araya, M. B. and F. S. Todd. 1987. Status of the Humboldt pen-guin in Chile following the 1982–83 El Niño. Proceedings of the Jean Delacour/IFCB Symposium, Los Angeles, California: 148–157.
Meteorologisches Taschenbuch
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Nahrungsanalysen bei chilenischen Humboldt-pinguinen
  • C Herling
Herling, C. (2001). Nahrungsanalysen bei chilenischen Humboldt-pinguinen. M. Sc. Thesis, Kiel, Germany.
Chile; Climate & seabirds. In: 1997-98 El Nĩo/Southern Oscillation (ENSO 97-98)-one of the most severe ENSO events in history
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Boletín de Alerta Climático, Instituto Oceanográfico de la Armada
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Animal tracking by satellite
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