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Tom Hart - One of the best experts on this subject based on the ideXlab platform.
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A global population assessment of the Chinstrap Penguin (Pygoscelis antarctica).
Scientific reports, 2020Co-Authors: Noah Strycker, Tom Hart, Michael Wethington, Alex Borowicz, Steve Forrest, Chandi Witharana, Heather J. LynchAbstract:Using satellite imagery, drone imagery, and ground counts, we have assembled the first comprehensive global population assessment of Chinstrap Penguins (Pygoscelis antarctica) at 3.42 (95th-percentile CI: [2.98, 4.00]) million breeding pairs across 375 extant colonies. Twenty-three previously known Chinstrap Penguin colonies are found to be absent or extirpated. We identify five new colonies, and 21 additional colonies previously unreported and likely missed by previous surveys. Limited or imprecise historical data prohibit our assessment of population change at 35% of all Chinstrap Penguin colonies. Of colonies for which a comparison can be made to historical counts in the 1980s, 45% have probably or certainly declined and 18% have probably or certainly increased. Several large colonies in the South Sandwich Islands, where conditions apparently remain favorable for Chinstrap Penguins, cannot be assessed against a historical benchmark. Our population assessment provides a detailed baseline for quantifying future changes in Chinstrap Penguin abundance, sheds new light on the environmental drivers of Chinstrap Penguin population dynamics in Antarctica, and contributes to ongoing monitoring and conservation efforts at a time of climate change and concerns over declining krill abundance in the Southern Ocean.
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Identification of Circovirus Genome in a Chinstrap Penguin (Pygoscelis antarcticus) and Adélie Penguin (Pygoscelis adeliae) on the Antarctic Peninsula.
Viruses, 2020Co-Authors: Hila Levy, Caitlin Black, Steven R. Fiddaman, Anni Djurhuus, Adrian Smith, Tom HartAbstract:Circoviruses infect a variety of animal species and have small (~1.8–2.2 kb) circular single-stranded DNA genomes. Recently a Penguin circovirus (PenCV) was identified associated with an Adelie Penguin (Pygoscelis adeliae) with feather disorder and in the cloacal swabs of three asymptomatic Adelie Penguins at Cape Crozier, Antarctica. A total of 75 cloacal swab samples obtained from adults and chicks of three species of Penguin (genus: Pygoscelis) from seven Antarctic breeding colonies (South Shetland Islands and Western Antarctic Peninsula) in the 2015−2016 breeding season were screened for PenCV. We identified new variants of PenCV in one Adelie Penguin and one Chinstrap Penguin (Pygoscelis antarcticus) from Port Charcot, Booth Island, Western Antarctic Peninsula, a site home to all three species of Pygoscelid Penguins. These two PenCV genomes (length of 1986 nucleotides) share > 99% genome-wide nucleotide identity with each other and share ~87% genome-wide nucleotide identity with the PenCV sequences described from Adelie Penguins at Cape Crozier ~4400 km away in East Antarctica. We did not find any evidence of recombination among PenCV sequences. This is the first report of PenCV in Chinstrap Penguins and the first detection outside of Ross Island, East Antarctica. Given the limited knowledge on Antarctic animal viral diversity, future samples from Antarctic wildlife should be screened for these and other viruses to determine the prevalence and potential impact of viral infections.
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time lapse imagery of adelie Penguins reveals differential winter strategies and breeding site occupation
PLOS ONE, 2018Co-Authors: Caitlin Black, Louise Emmerson, Daniel Lunn, Colin Southwell, Tom HartAbstract:Polar seabirds adopt different over-wintering strategies to survive and build condition during the critical winter period. Penguin species either reside at the colony during the winter months or migrate long distances. Tracking studies and survey methods have revealed differences in winter migration routes among Penguin species and colonies, dependent on both biotic and abiotic factors present. However, scan sampling methods are rarely used to reveal non-breeding behaviors during winter and little is known about presence at the colony site over this period. Here we show that Adelie Penguins on the Yalour Islands in the Western Antarctic Peninsula (WAP) are present year-round at the colony and undergo a mid-winter peak in abundance during winter. We found a negative relationship between daylight hours and Penguin abundance when either open water or compact ice conditions were present, suggesting that Penguins return to the breeding colony when visibility is lowest for at-sea foraging and when either extreme low or high levels of sea ice exist offshore. In contrast, Adelie Penguins breeding in East Antarctica were not observed at the colonies during winter, suggesting that Adelie Penguins undergo differential winter strategies in the marginal ice zone on the WAP compared to those in East Antarctica. These results demonstrate that cameras can successfully monitor wildlife year-round in areas that are largely inaccessible during winter.
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seasonal consistency and individual variation in foraging strategies differ among and within pygoscelis Penguin species in the antarctic peninsula region
Marine Biology, 2017Co-Authors: Rachael Herman, Maria Virginia Petry, Tom Hart, Fernanda Caminha Leal Valls, Wayne Z Trivelpiece, Michael J PolitoAbstract:Past research during the breeding season in the Antarctic Peninsula region indicates that gentoo Penguins (Pygoscelis papua) are generalist foragers whereas Adelie (P. adeliae) and chinstrap (P. antarcticus) Penguins tend to specialize on Antarctic krill (Euphausia superba). However, little is known about the degree of temporal consistency in the diets and foraging habitats of these three species, particularly at the individual level. Such year-round and inter-annual dietary understanding is important to help interpret contrasting trends in their populations. We used carbon and nitrogen stable isotope analysis of blood and feathers to evaluate seasonal shifts in diet and individual foraging consistency within Pygoscelis Penguin species breeding in the South Shetland Islands as well as among three geographically distinct gentoo Penguin populations in the western Antarctic Peninsula and South Shetland Islands. We found that gentoo Penguins exhibited a generalist foraging strategy with individual consistency, Adelie Penguins exhibited an intermediate generalist foraging strategy with little individual consistency, and chinstrap Penguins exhibited a specialized diet with little inter-individual variation. Our results also indicated that all three species have greater variation in foraging habitat use during the post-breeding season compared to the breeding season. Finally, we observed differences in the degree of seasonal shifts in population level diet and consistency in foraging strategies at the individual level across the three gentoo Penguin populations examined. This suggests that Pygoscelis Penguins can differ in diets and foraging habitat use not only at the population level among species, sites, and seasons, but also in the level of variation within populations, and in the degree of seasonal consistency among individuals.
Michael J Polito - One of the best experts on this subject based on the ideXlab platform.
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seasonal consistency and individual variation in foraging strategies differ among and within pygoscelis Penguin species in the antarctic peninsula region
Marine Biology, 2017Co-Authors: Rachael Herman, Maria Virginia Petry, Tom Hart, Fernanda Caminha Leal Valls, Wayne Z Trivelpiece, Michael J PolitoAbstract:Past research during the breeding season in the Antarctic Peninsula region indicates that gentoo Penguins (Pygoscelis papua) are generalist foragers whereas Adelie (P. adeliae) and chinstrap (P. antarcticus) Penguins tend to specialize on Antarctic krill (Euphausia superba). However, little is known about the degree of temporal consistency in the diets and foraging habitats of these three species, particularly at the individual level. Such year-round and inter-annual dietary understanding is important to help interpret contrasting trends in their populations. We used carbon and nitrogen stable isotope analysis of blood and feathers to evaluate seasonal shifts in diet and individual foraging consistency within Pygoscelis Penguin species breeding in the South Shetland Islands as well as among three geographically distinct gentoo Penguin populations in the western Antarctic Peninsula and South Shetland Islands. We found that gentoo Penguins exhibited a generalist foraging strategy with individual consistency, Adelie Penguins exhibited an intermediate generalist foraging strategy with little individual consistency, and chinstrap Penguins exhibited a specialized diet with little inter-individual variation. Our results also indicated that all three species have greater variation in foraging habitat use during the post-breeding season compared to the breeding season. Finally, we observed differences in the degree of seasonal shifts in population level diet and consistency in foraging strategies at the individual level across the three gentoo Penguin populations examined. This suggests that Pygoscelis Penguins can differ in diets and foraging habitat use not only at the population level among species, sites, and seasons, but also in the level of variation within populations, and in the degree of seasonal consistency among individuals.
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contrasting specialist and generalist patterns facilitate foraging niche partitioning in sympatric populations of pygoscelis Penguins
Marine Ecology Progress Series, 2015Co-Authors: Michael J Polito, Wayne Z Trivelpiece, William P Patterson, Nina J Karnovsky, Christian S Reiss, Steven D EmslieAbstract:Specialization is a common mechanism of niche differentiation that can lead to eco- logical co-existence among species. However, species with specialized habitat or dietary require- ments often exhibit a high degree of sensitivity to environmental change. Understanding patterns of specialization and niche segregation among Antarctic marine predators is of increased impor- tance because of recent climate-driven reductions in a key prey species, Antarctic krill Euphausia superba. We examined the stomach contents and stable isotope values of sympatric chinstrap Pygoscelis antarctica and gentoo P. papua Penguins across 5 breeding seasons at Cape Shirreff, Livingston Island, Antarctica. Our goal was to examine foraging niche segregation and the degree of specialization between species during the chick-rearing period. Dietary and isotopic foraging niches indicated consistent niche partitioning with higher krill consumption and greater use of off- shore foraging habitats by chinstrap relative to gentoo Penguins. While chinstrap Penguin diets were dominated by krill with little variation, gentoo Penguins exhibited broader dietary and iso- topic niches with a higher degree of variation. There was little evidence that shifts in the availabil- ity of adult krill influenced Penguin diets or foraging niches during our study, though the contrast- ing foraging strategies identified provide insight into the differing population trends observed between Penguin species. The narrower foraging niche observed in declining chinstrap Penguin populations indicates that they are likely highly sensitive to declines in the abundance of Antarc- tic krill. In contrast, the generalist niche exhibited by recently expanding gentoo Penguin popula- tions is likely better suited to the rapidly changing environmental conditions in the Antarctic Peninsula.
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first direct site wide Penguin survey at deception island antarctica suggests significant declines in breeding chinstrap Penguins
Polar Biology, 2012Co-Authors: Ron Naveen, Heather J. Lynch, Steven Forrest, Thomas Mueller, Michael J PolitoAbstract:Deception Island (62°57′S, 60°38′W) is one of the most frequently visited locations in Antarctica, prompting speculation that tourism may have a negative impact on the island’s breeding chinstrap Penguins (Pygoscelis antarctica). Discussions regarding appropriate management of Deception Island and its largest Penguin colony at Baily Head have thus far operated in the absence of concrete information regarding the current size of the Penguin population at Deception Island or long-term changes in abundance. In the first ever field census of individual Penguin nests at Deception Island (December 2–14, 2011), we find 79,849 breeding pairs of chinstrap Penguins, including 50,408 breeding pairs at Baily Head and 19,177 breeding pairs at Vapour Col. Our field census, combined with a simulation designed to capture uncertainty in an earlier population estimate by Shuford and Spear (Br Antarct Surv Bull 81:19–30, 1988), suggests a significant (>50 %) decline in the abundance of chinstraps breeding at Baily Head since 1986/1987. A comparative analysis of high-resolution satellite imagery for the 2002/2003 and the 2009/2010 seasons suggests a 39 % (95th percentile CI = 6–71 %) decline (from 85,473 ± 23,352 to 52,372 ± 14,309 breeding pairs) over that 7-year period and provides independent confirmation of population decline in the abundance of breeding chinstrap Penguins at Baily Head. The decline in chinstrap Penguins at Baily Head is consistent with declines in this species throughout the region, including sites that receive little or no tourism; as a consequence of regional environmental changes that currently represent the dominant influence on Penguin dynamics, we cannot ascribe any direct link between chinstrap declines and tourism from this study.
Caitlin Black - One of the best experts on this subject based on the ideXlab platform.
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Identification of Circovirus Genome in a Chinstrap Penguin (Pygoscelis antarcticus) and Adélie Penguin (Pygoscelis adeliae) on the Antarctic Peninsula.
Viruses, 2020Co-Authors: Hila Levy, Caitlin Black, Steven R. Fiddaman, Anni Djurhuus, Adrian Smith, Tom HartAbstract:Circoviruses infect a variety of animal species and have small (~1.8–2.2 kb) circular single-stranded DNA genomes. Recently a Penguin circovirus (PenCV) was identified associated with an Adelie Penguin (Pygoscelis adeliae) with feather disorder and in the cloacal swabs of three asymptomatic Adelie Penguins at Cape Crozier, Antarctica. A total of 75 cloacal swab samples obtained from adults and chicks of three species of Penguin (genus: Pygoscelis) from seven Antarctic breeding colonies (South Shetland Islands and Western Antarctic Peninsula) in the 2015−2016 breeding season were screened for PenCV. We identified new variants of PenCV in one Adelie Penguin and one Chinstrap Penguin (Pygoscelis antarcticus) from Port Charcot, Booth Island, Western Antarctic Peninsula, a site home to all three species of Pygoscelid Penguins. These two PenCV genomes (length of 1986 nucleotides) share > 99% genome-wide nucleotide identity with each other and share ~87% genome-wide nucleotide identity with the PenCV sequences described from Adelie Penguins at Cape Crozier ~4400 km away in East Antarctica. We did not find any evidence of recombination among PenCV sequences. This is the first report of PenCV in Chinstrap Penguins and the first detection outside of Ross Island, East Antarctica. Given the limited knowledge on Antarctic animal viral diversity, future samples from Antarctic wildlife should be screened for these and other viruses to determine the prevalence and potential impact of viral infections.
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time lapse imagery of adelie Penguins reveals differential winter strategies and breeding site occupation
PLOS ONE, 2018Co-Authors: Caitlin Black, Louise Emmerson, Daniel Lunn, Colin Southwell, Tom HartAbstract:Polar seabirds adopt different over-wintering strategies to survive and build condition during the critical winter period. Penguin species either reside at the colony during the winter months or migrate long distances. Tracking studies and survey methods have revealed differences in winter migration routes among Penguin species and colonies, dependent on both biotic and abiotic factors present. However, scan sampling methods are rarely used to reveal non-breeding behaviors during winter and little is known about presence at the colony site over this period. Here we show that Adelie Penguins on the Yalour Islands in the Western Antarctic Peninsula (WAP) are present year-round at the colony and undergo a mid-winter peak in abundance during winter. We found a negative relationship between daylight hours and Penguin abundance when either open water or compact ice conditions were present, suggesting that Penguins return to the breeding colony when visibility is lowest for at-sea foraging and when either extreme low or high levels of sea ice exist offshore. In contrast, Adelie Penguins breeding in East Antarctica were not observed at the colonies during winter, suggesting that Adelie Penguins undergo differential winter strategies in the marginal ice zone on the WAP compared to those in East Antarctica. These results demonstrate that cameras can successfully monitor wildlife year-round in areas that are largely inaccessible during winter.
Hila Levy - One of the best experts on this subject based on the ideXlab platform.
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Identification of Circovirus Genome in a Chinstrap Penguin (Pygoscelis antarcticus) and Adélie Penguin (Pygoscelis adeliae) on the Antarctic Peninsula.
Viruses, 2020Co-Authors: Hila Levy, Caitlin Black, Steven R. Fiddaman, Anni Djurhuus, Adrian Smith, Tom HartAbstract:Circoviruses infect a variety of animal species and have small (~1.8–2.2 kb) circular single-stranded DNA genomes. Recently a Penguin circovirus (PenCV) was identified associated with an Adelie Penguin (Pygoscelis adeliae) with feather disorder and in the cloacal swabs of three asymptomatic Adelie Penguins at Cape Crozier, Antarctica. A total of 75 cloacal swab samples obtained from adults and chicks of three species of Penguin (genus: Pygoscelis) from seven Antarctic breeding colonies (South Shetland Islands and Western Antarctic Peninsula) in the 2015−2016 breeding season were screened for PenCV. We identified new variants of PenCV in one Adelie Penguin and one Chinstrap Penguin (Pygoscelis antarcticus) from Port Charcot, Booth Island, Western Antarctic Peninsula, a site home to all three species of Pygoscelid Penguins. These two PenCV genomes (length of 1986 nucleotides) share > 99% genome-wide nucleotide identity with each other and share ~87% genome-wide nucleotide identity with the PenCV sequences described from Adelie Penguins at Cape Crozier ~4400 km away in East Antarctica. We did not find any evidence of recombination among PenCV sequences. This is the first report of PenCV in Chinstrap Penguins and the first detection outside of Ross Island, East Antarctica. Given the limited knowledge on Antarctic animal viral diversity, future samples from Antarctic wildlife should be screened for these and other viruses to determine the prevalence and potential impact of viral infections.
Rachael Herman - One of the best experts on this subject based on the ideXlab platform.
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multi modal survey of adelie Penguin mega colonies reveals the danger islands as a seabird hotspot
Scientific Reports, 2018Co-Authors: Alex Borowicz, Rachael Herman, Steven Forrest, Philip Mcdowall, Casey Youngflesh, Thomas Sayremccord, Gemma V Clucas, Melissa RiderAbstract:Despite concerted international effort to track and interpret shifts in the abundance and distribution of Adelie Penguins, large populations continue to be identified. Here we report on a major hotspot of Adelie Penguin abundance identified in the Danger Islands off the northern tip of the Antarctic Peninsula (AP). We present the first complete census of Pygoscelis spp. Penguins in the Danger Islands, estimated from a multi-modal survey consisting of direct ground counts and computer-automated counts of unmanned aerial vehicle (UAV) imagery. Our survey reveals that the Danger Islands host 751,527 pairs of Adelie Penguins, more than the rest of AP region combined, and include the third and fourth largest Adelie Penguin colonies in the world. Our results validate the use of Landsat medium-resolution satellite imagery for the detection of new or unknown Penguin colonies and highlight the utility of combining satellite imagery with ground and UAV surveys. The Danger Islands appear to have avoided recent declines documented on the Western AP and, because they are large and likely to remain an important hotspot for avian abundance under projected climate change, deserve special consideration in the negotiation and design of Marine Protected Areas in the region.
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seasonal consistency and individual variation in foraging strategies differ among and within pygoscelis Penguin species in the antarctic peninsula region
Marine Biology, 2017Co-Authors: Rachael Herman, Maria Virginia Petry, Tom Hart, Fernanda Caminha Leal Valls, Wayne Z Trivelpiece, Michael J PolitoAbstract:Past research during the breeding season in the Antarctic Peninsula region indicates that gentoo Penguins (Pygoscelis papua) are generalist foragers whereas Adelie (P. adeliae) and chinstrap (P. antarcticus) Penguins tend to specialize on Antarctic krill (Euphausia superba). However, little is known about the degree of temporal consistency in the diets and foraging habitats of these three species, particularly at the individual level. Such year-round and inter-annual dietary understanding is important to help interpret contrasting trends in their populations. We used carbon and nitrogen stable isotope analysis of blood and feathers to evaluate seasonal shifts in diet and individual foraging consistency within Pygoscelis Penguin species breeding in the South Shetland Islands as well as among three geographically distinct gentoo Penguin populations in the western Antarctic Peninsula and South Shetland Islands. We found that gentoo Penguins exhibited a generalist foraging strategy with individual consistency, Adelie Penguins exhibited an intermediate generalist foraging strategy with little individual consistency, and chinstrap Penguins exhibited a specialized diet with little inter-individual variation. Our results also indicated that all three species have greater variation in foraging habitat use during the post-breeding season compared to the breeding season. Finally, we observed differences in the degree of seasonal shifts in population level diet and consistency in foraging strategies at the individual level across the three gentoo Penguin populations examined. This suggests that Pygoscelis Penguins can differ in diets and foraging habitat use not only at the population level among species, sites, and seasons, but also in the level of variation within populations, and in the degree of seasonal consistency among individuals.
