The Experts below are selected from a list of 98757 Experts worldwide ranked by ideXlab platform
Daniel T Ksepka - One of the best experts on this subject based on the ideXlab platform.
-
A history of shifting fortunes for African Penguins
Zoological Journal of the Linnean Society, 2013Co-Authors: Daniel B. Thomas, Daniel T KsepkaAbstract:Africa is home today to only a single breeding species of penguin, Spheniscus demersus (black-footed penguin), which is endangered with extinction. Spheniscus demersus has been the only breeding species of penguin to share African coastlines with humans over the last 400 000 years. Interestingly, African penguin diversity was substantially higher before the evolution of archaic humans. The fossil record indicates that a diverse assemblage of penguin species inhabited the southern African coasts for much of the Neogene. Previous excavations have identified four distinct species in Early Pliocene coastal marine deposits. Here we extend this pattern of high diversity and report the oldest record of Penguins from Africa. Seventeen penguin specimens were identified from the Saldanha Steel locality, revealing the presence of at least four distinct species in South Africa during the Miocene. The largest of these species reached the size of the extant Aptenodytes patagonicus (king penguin), whereas the smallest was approximately the size of the smallest extant penguin Eudyptula minor (little blue penguin). Recovery of Miocene penguin remains is in accordance with earlier predictions of multiple pre-Pliocene colonizations of Africa and supports a higher level of ecological diversity amongst African Penguins in the past. © 2013 The Linnean Society of London
-
Osteology of Icadyptes salasi, a giant penguin from the Eocene of Peru.
Journal of Anatomy, 2008Co-Authors: Daniel T Ksepka, Thomas J. Devries, Julia A. Clarke, Mario UrbinaAbstract:We present the first detailed description of the giant Eocene penguin Icadyptes salasi . The species is characterized by a narrow skull with a hyper-elongate spear-like beak, a robust cervical column and a powerful flipper. The bony beak tip of Icadyptes is formed by fusion of several elements and is unique among Penguins, differing markedly from previously described giant penguin beaks. Vascular canal patterning similar to that of boobies, frigatebirds and albatrosses suggests I. salasi may have had a thin, sheet-like rhamphotheca unlike the thick rugose rhamphotheca of modern Penguins. Together, these features suggest a novel ecology for I. salasi , most likely involving the capture of larger prey items via spearing. As the first described giant penguin specimen to preserve a complete wing skeleton, the I. salasi holotype yields significant insight into the shape, proportions and orientation of the wing in giant Penguins. In articulation, the forelimb of I. salasi is straighter, permitting less manus and antibrachium flexion, than previous depictions of giant penguin wings. Cross-sections of the humerus and ulna reveal a level of osteosclerosis equalling or surpassing that of extant Penguins. Based on ontogenetic data from extant Penguins and the morphology of the carpometacarpus of I. salasi , we infer the retention of a free alular phalanx in basal Penguins. Previously, the status of this element in Penguins was disputed. Differences in the proportions of the manual phalanges contribute to a more abruptly tapering wingtip in I. salasi compared with crown Penguins. Fossils from Peru, including the I. salasi holotype specimen, document that Penguins expanded to nearly the whole of their extant latitudinal range early in their evolutionary history and during one of the warmest intervals in the Cenozoic.
-
paleogene equatorial Penguins challenge the proposed relationship between biogeography diversity and cenozoic climate change
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Julia A. Clarke, Mario Urbina, Daniel T Ksepka, Marcelo Stucchi, Norberto P Giannini, Sara Bertelli, Yanina Narvaez, Clint A BoydAbstract:New penguin fossils from the Eocene of Peru force a reevaluation of previous hypotheses regarding the causal role of climate change in penguin evolution. Repeatedly it has been proposed that Penguins originated in high southern latitudes and arrived at equatorial regions relatively recently (e.g., 4–8 million years ago), well after the onset of latest Eocene/Oligocene global cooling and increases in polar ice volume. By contrast, new discoveries from the middle and late Eocene of Peru reveal that Penguins invaded low latitudes >30 million years earlier than prior data suggested, during one of the warmest intervals of the Cenozoic. A diverse fauna includes two new species, here reported from two of the best exemplars of Paleogene Penguins yet recovered. The most comprehensive phylogenetic analysis of Sphenisciformes to date, combining morphological and molecular data, places the new species outside the extant penguin radiation (crown clade: Spheniscidae) and supports two separate dispersals to equatorial (paleolatitude ≈14°S) regions during greenhouse earth conditions. One new species, Perudyptes devriesi, is among the deepest divergences within Sphenisciformes. The second, Icadyptes salasi, is the most complete giant (>1.5 m standing height) penguin yet described. Both species provide critical information on early penguin cranial osteology, trends in penguin body size, and the evolution of the penguin flipper.
Mario Urbina - One of the best experts on this subject based on the ideXlab platform.
-
Osteology of Icadyptes salasi, a giant penguin from the Eocene of Peru.
Journal of Anatomy, 2008Co-Authors: Daniel T Ksepka, Thomas J. Devries, Julia A. Clarke, Mario UrbinaAbstract:We present the first detailed description of the giant Eocene penguin Icadyptes salasi . The species is characterized by a narrow skull with a hyper-elongate spear-like beak, a robust cervical column and a powerful flipper. The bony beak tip of Icadyptes is formed by fusion of several elements and is unique among Penguins, differing markedly from previously described giant penguin beaks. Vascular canal patterning similar to that of boobies, frigatebirds and albatrosses suggests I. salasi may have had a thin, sheet-like rhamphotheca unlike the thick rugose rhamphotheca of modern Penguins. Together, these features suggest a novel ecology for I. salasi , most likely involving the capture of larger prey items via spearing. As the first described giant penguin specimen to preserve a complete wing skeleton, the I. salasi holotype yields significant insight into the shape, proportions and orientation of the wing in giant Penguins. In articulation, the forelimb of I. salasi is straighter, permitting less manus and antibrachium flexion, than previous depictions of giant penguin wings. Cross-sections of the humerus and ulna reveal a level of osteosclerosis equalling or surpassing that of extant Penguins. Based on ontogenetic data from extant Penguins and the morphology of the carpometacarpus of I. salasi , we infer the retention of a free alular phalanx in basal Penguins. Previously, the status of this element in Penguins was disputed. Differences in the proportions of the manual phalanges contribute to a more abruptly tapering wingtip in I. salasi compared with crown Penguins. Fossils from Peru, including the I. salasi holotype specimen, document that Penguins expanded to nearly the whole of their extant latitudinal range early in their evolutionary history and during one of the warmest intervals in the Cenozoic.
-
paleogene equatorial Penguins challenge the proposed relationship between biogeography diversity and cenozoic climate change
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Julia A. Clarke, Mario Urbina, Daniel T Ksepka, Marcelo Stucchi, Norberto P Giannini, Sara Bertelli, Yanina Narvaez, Clint A BoydAbstract:New penguin fossils from the Eocene of Peru force a reevaluation of previous hypotheses regarding the causal role of climate change in penguin evolution. Repeatedly it has been proposed that Penguins originated in high southern latitudes and arrived at equatorial regions relatively recently (e.g., 4–8 million years ago), well after the onset of latest Eocene/Oligocene global cooling and increases in polar ice volume. By contrast, new discoveries from the middle and late Eocene of Peru reveal that Penguins invaded low latitudes >30 million years earlier than prior data suggested, during one of the warmest intervals of the Cenozoic. A diverse fauna includes two new species, here reported from two of the best exemplars of Paleogene Penguins yet recovered. The most comprehensive phylogenetic analysis of Sphenisciformes to date, combining morphological and molecular data, places the new species outside the extant penguin radiation (crown clade: Spheniscidae) and supports two separate dispersals to equatorial (paleolatitude ≈14°S) regions during greenhouse earth conditions. One new species, Perudyptes devriesi, is among the deepest divergences within Sphenisciformes. The second, Icadyptes salasi, is the most complete giant (>1.5 m standing height) penguin yet described. Both species provide critical information on early penguin cranial osteology, trends in penguin body size, and the evolution of the penguin flipper.
Akiko Kato - One of the best experts on this subject based on the ideXlab platform.
-
The diving behaviour of little Penguins in Western Australia predisposes them to risk of injury by watercraft
Aquatic Conservation: Marine and Freshwater Ecosystems, 2020Co-Authors: Belinda Cannell, Yan Ropert‐coudert, Ben Radford, Akiko KatoAbstract:The most western little penguin colony globally, and the most northern in Western Australia (WA) is found on Penguin Island, WA. The Penguins use coastal bays that are also used extensively by recreational watercraft. These Penguins have been found to either dive predominantly to shallow depths of 1–5 m or to depths >8 m. It is thus hypothesized that (a) both the shallow and deeper diving Penguins can potentially be disturbed or injured by these watercraft but that the risk will differ between the two diving strategies, and (b) that risk of injury for both is greater during the summer and autumn, when people are more likely to use watercraft. This was tested by attaching data loggers to little Penguins during chick rearing and by investigating necropsy records. Diving activity was studied for the very shallow and relatively deeper diving Penguins separately, and we considered the Penguins were vulnerable to interactions with watercraft when they were within the top 2 m of the water column or at the surface. Shallow‐diving Penguins executed >1,200 dives per day, 64% of dives occurred within the top 2 m, and they were vulnerable for approximately two‐thirds of their time at sea. The deeper diving Penguins executed fewer dives. Almost half of dives were to ≥10 m, yet they were vulnerable for almost one‐third of their time at sea. Their post‐dive recovery was also longer. Thus, the risk of interaction from watercraft differs depending on the diving behaviour. This study highlights the potential impact to little Penguins throughout Australia and New Zealand.
-
Hydrodynamic handicaps and organizational complexity in the foraging behavior of two free-ranging penguin species
Animal Biotelemetry, 2015Co-Authors: Xavier Meyer, Akiko Kato, Andrew J J Macintosh, André Chiaradia, Yan Ropert‐coudertAbstract:Background: Animal movement exhibits self-similarity across a range of both spatial and temporal scales reminiscent of statistical fractals. Stressors are known to induce changes in these statistical patterns of behavior, although the direction and interpretation of such changes are not always clear. We examined whether the imposition of known hydrodynamic disruptors, bio-logging devices and flipper bands, induces changes in the temporal organization (complexity) of foraging sequences in two penguin species, little Penguins (Eudyptula minor) and Adélie Penguins (Pygoscelis adeliae). Results: Detrended fluctuation analysis showed that foraging sequences produced by little Penguins carrying larger loggers were more complex, i.e., were more erratic tending toward greater stochasticity, than those carrying smaller loggers. However, logger size did not affect complexity in foraging sequences of Adélie Penguins. Logger position was associated only weakly with altered complexity in little Penguins, with individuals carrying loggers in the middle of their backs displaying slightly more complex dive sequences than those carrying loggers lower on their backs. Finally, despite their known negative effects on penguin fitness, flipper bands were not associated with dive sequence complexity in little Penguins. Conclusions: Despite that externally attached devices can disrupt certain behavioral parameters in diving seabirds, we found mixed evidence in support of the hypothesis that such devices significantly disrupt the time-structured organizational properties of foraging sequences in the two penguin species investigated. However, smaller species carrying larger loggers, and perhaps those positioned higher on their backs, may experience an added element of noise in their behavioral sequences that may indicate a departure from foraging behavior observed under normal, unburdened conditions.
Vanesa L. Pietri - One of the best experts on this subject based on the ideXlab platform.
-
A new fossil from the mid-Paleocene of New Zealand reveals an unexpected diversity of world's oldest Penguins.
Die Naturwissenschaften, 2017Co-Authors: Vanesa L. Pietri, R Paul ScofieldAbstract:We describe leg bones of a giant penguin from the mid-Paleocene Waipara Greensand of New Zealand. The specimens were found at the type locality of Waimanu manneringi and together with this species they constitute the oldest penguin fossils known to date. Tarsometatarsus dimensions indicate a species that reached the size of Anthropornis nordenskjoeldi, one of the largest known penguin species. Stem group Penguins therefore attained a giant size very early in their evolution, with this gigantism existing for more than 30 million years. The new fossils are from a species that is phylogenetically more derived than Waimanu, and the unexpected coexistence of Waimanu with more derived stem group Sphenisciformes documents a previously unknown diversity amongst the world's oldest Penguins. The characteristic tarsometatarsus shape of Penguins evolved early on, and the significant morphological disparity between Waimanu and the new fossil conflicts with recent Paleocene divergence estimates for Penguins, suggesting an older, Late Cretaceous, origin.
-
A new fossil from the mid-Paleocene of New Zealand reveals an unexpected diversity of world’s oldest Penguins
Naturwissenschaften, 2017Co-Authors: Vanesa L. Pietri, R. Paul ScofieldAbstract:We describe leg bones of a giant penguin from the mid-Paleocene Waipara Greensand of New Zealand. The specimens were found at the type locality of Waimanu manneringi and together with this species they constitute the oldest penguin fossils known to date. Tarsometatarsus dimensions indicate a species that reached the size of Anthropornis nordenskjoeldi, one of the largest known penguin species. Stem group Penguins therefore attained a giant size very early in their evolution, with this gigantism existing for more than 30 million years. The new fossils are from a species that is phylogenetically more derived than Waimanu, and the unexpected coexistence of Waimanu with more derived stem group Sphenisciformes documents a previously unknown diversity amongst the world’s oldest Penguins. The characteristic tarsometatarsus shape of Penguins evolved early on, and the significant morphological disparity between Waimanu and the new fossil conflicts with recent Paleocene divergence estimates for Penguins, suggesting an older, Late Cretaceous, origin.
P H Hemsworth - One of the best experts on this subject based on the ideXlab platform.
-
Effects of Regulating Visitor Viewing Proximity and the Intensity of Visitor Behaviour on Little Penguin (Eudyptula minor) Behaviour and Welfare
'MDPI AG', 2019Co-Authors: Sj Chiew, Sally L. Sherwen, K L Butler, Gj Coleman, Kv Fanson, P H HemsworthAbstract:We examined the effects of regulating the viewing proximity of visitors and the intensity of visitor behaviour on behaviours indicative of fear and stress physiology of 15 zoo-housed little Penguins (Eudyptula minor). A 2 × 2 factorial fully randomised design was used to examine the effects of regulating: 1) the viewing proximity of visitors to enclosure, 'normal viewing distance' and 'increased viewing distance' (using a physical barrier set up 2 m away from the enclosure), and 2) the intensity of visitor behaviour, 'unregulated visitor behaviour' and 'regulated visitor behaviour' (using signage and uniformed personnel). In addition, a treatment consisting of closing the enclosure to visitors was included. Penguin behaviour, visitor numbers and visitor behaviour were recorded by CCTV video recordings and direct observations, respectively. Penguin faecal glucocorticoid metabolites were also analysed as a measure of stress physiology. We found that increased viewing distance reduced (p 0.05). As the regulation of viewing proximity increased from a closed exhibit to an open exhibit with increased viewing distance, and then to an open exhibit with normal viewing distance, this increased the proportion of Penguins huddling (p = 0.0011), vigilant (p = 0.0060) and retreating (p = 0.00013), and decreased the proportion of Penguins within 1 m of the visitor viewing area (p = 0.00066), surface swimming (p = 0.00091) and preening in the water (p = 0.042). There were also limited effects of regulating visitor behaviour on penguin behaviour. No treatment effects were found on faecal glucocorticoid metabolites (p > 0.05). These results indicate that regulating visitor viewing proximity affects penguin behaviours indicative of fear and visitor behaviour. This suggests that close visitor contact can be fear-provoking for little Penguins but increasing the distance between visitors and Penguins can reduce fear responses of Penguins by regulating both viewing proximity and visitor behaviour. However, it is unclear whether these changes in penguin behaviour are due to the increased separation between visitors and Penguins and/or specific visitor behaviours associated with close viewing proximity to the enclosure, such as leaning over the enclosure or tactile contact with the pool, which are impeded when visitors are further away
-
Effects of Regulating Visitor Viewing Proximity and the Intensity of Visitor Behaviour on Little Penguin (Eudyptula minor) Behaviour and Welfare
MDPI AG, 2019Co-Authors: Samantha J. Chiew, Sally L. Sherwen, Kv Fanson, Kym L. Butler, Grahame J. Coleman, P H HemsworthAbstract:We examined the effects of regulating the viewing proximity of visitors and the intensity of visitor behaviour on behaviours indicative of fear and stress physiology of 15 zoo-housed little Penguins (Eudyptula minor). A 2 × 2 factorial fully randomised design was used to examine the effects of regulating: (1) the viewing proximity of visitors to enclosure, ‘normal viewing distance’ and ’increased viewing distance’ (using a physical barrier set up 2 m away from the enclosure), and (2) the intensity of visitor behaviour, ‘unregulated visitor behaviour’ and ‘regulated visitor behaviour’ (using signage and uniformed personnel). In addition, a treatment consisting of closing the enclosure to visitors was included. Penguin behaviour, visitor numbers and visitor behaviour were recorded by CCTV video recordings and direct observations, respectively. Penguin faecal glucocorticoid metabolites were also analysed as a measure of stress physiology. We found that increased viewing distance reduced (p < 0.05) all visitor behaviours except for loud vocalisations and tactile contact with Penguins. However, there were no direct effects of signage and uniformed personnel on visitor behaviour (p > 0.05). As the regulation of viewing proximity increased from a closed exhibit to an open exhibit with increased viewing distance, and then to an open exhibit with normal viewing distance, this increased the proportion of Penguins huddling (p = 0.0011), vigilant (p = 0.0060) and retreating (p = 0.00013), and decreased the proportion of Penguins within 1 m of the visitor viewing area (p = 0.00066), surface swimming (p = 0.00091) and preening in the water (p = 0.042). There were also limited effects of regulating visitor behaviour on penguin behaviour. No treatment effects were found on faecal glucocorticoid metabolites (p > 0.05). These results indicate that regulating visitor viewing proximity affects penguin behaviours indicative of fear and visitor behaviour. This suggests that close visitor contact can be fear-provoking for little Penguins but increasing the distance between visitors and Penguins can reduce fear responses of Penguins by regulating both viewing proximity and visitor behaviour. However, it is unclear whether these changes in penguin behaviour are due to the increased separation between visitors and Penguins and/or specific visitor behaviours associated with close viewing proximity to the enclosure, such as leaning over the enclosure or tactile contact with the pool, which are impeded when visitors are further away
-
little Penguins eudyptula minor show increased avoidance aggression and vigilance in response to zoo visitors
Applied Animal Behaviour Science, 2015Co-Authors: Sally L. Sherwen, Michael J L Magrath, K L Butler, P H HemsworthAbstract:Multiple studies have shown that human disturbance can have negative impacts on wild penguin populations. Penguins in zoos may also be susceptible to negative impacts from humans, but this has not previously been investigated. We examined the visitor effect on a group of 25 little Penguins, Eudyptula minor, by randomly imposing two treatments: (1) no visitor contact, which was achieved by closing the penguin exhibit on study days and (2) exposure to visitors, with the penguin exhibit open as usual. Treatments were imposed for 1-day periods, with five replicates of each treatment (total of 10 study days). Instantaneous point sampling and continuous sampling were used to record penguin behaviour including proximity to visitor viewing area, surface swimming, diving, vigilance, visibility, resting and intra-group aggression during a total of 3 h on each of the 10 study days. When exposed to visitors, Penguins showed increased levels of aggression (P = 0.02), huddling (P = 0.049) and behaviours indicative of avoidance of visitors including increased time spent positioned behind enclosure features (P = 0.024) and increased distance from the visitor viewing area (P = 0.002). These behavioural results suggest that the presence of visitors or some aspect of visitor behaviour may have been fear-provoking for these Penguins. To generalize beyond this group of animals and this enclosure requires further research.
