Foraging-Niche Separation of Breeding Gentoo and Chinstrap Penguins, South Shetland Islands, Antarctica

Miller, Aileen K.; Kappes, Michelle A.; Trivelpiece, Susan G.; Trivelpiece, Wayne Z.

doi:10.1525/cond.2010.090221

Cited by 70 publications

(94 citation statements)

References 38 publications

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“…Although we have found evidence of fishes (e.g., tissue, scales, and otoliths) in the diets of Adélie and chinstrap penguins breeding at our study sites in the South Shetland Islands (Admiralty Bay and Cape Shirreff) from about 25-30% of all samples annually, there has been no upward trend over the 30-y period. Furthermore, fish biomass in the diet averaged only 1-2% by mass of stomach contents with a maximum of 5% per year (14,38).…”

Section: Resultsmentioning

confidence: 99%

Variability in krill biomass links harvesting and climate warming to penguin population changes in Antarctica

Trivelpiece

Hinke

Miller

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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366

432

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The West Antarctic Peninsula (WAP) and adjacent Scotia Sea support abundant wildlife populations, many of which were nearly extirpated by humans. This region is also among the fastestwarming areas on the planet, with 5-6°C increases in mean winter air temperatures and associated decreases in winter sea-ice cover. These biological and physical perturbations have affected the ecosystem profoundly. One hypothesis guiding ecological interpretations of changes in top predator populations in this region, the "sea-ice hypothesis," proposes that reductions in winter sea ice have led directly to declines in "ice-loving" species by decreasing their winter habitat, while populations of "ice-avoiding" species have increased. However, 30 y of field studies and recent surveys of penguins throughout the WAP and Scotia Sea demonstrate this mechanism is not controlling penguin populations; populations of both ice-loving Adélie and ice-avoiding chinstrap penguins have declined significantly. We argue in favor of an alternative, more robust hypothesis that attributes both increases and decreases in penguin populations to changes in the abundance of their main prey, Antarctic krill. Unlike many other predators in this region, Adélie and chinstrap penguins were never directly harvested by man; thus, their population trajectories track the impacts of biological and environmental changes in this ecosystem. Linking trends in penguin abundance with trends in krill biomass explains why populations of Adélie and chinstrap penguins increased after competitors (fur seals, baleen whales, and some fishes) were nearly extirpated in the 19th to mid-20th centuries and currently are decreasing in response to climate change.S ea ice plays a critical role in structuring ecosystem dynamics throughout the West Antarctic Peninsula (WAP) and Scotia Sea, and variations in sea-ice extent are hypothesized to affect penguin populations directly. As seasonal sea-ice extent and duration declines in this region, the Adélie penguin (Pygoscelis adeliae), which favors pack-ice habitat in winter, should decline in population size, whereas the closely related chinstrap penguin (Pygoscelis antarctica), which forages in ice-free water during winter, should increase (1-5). The foundation for this hypothesis is based on a short (7-y) series of simultaneously observed decreases in nesting populations of Adélie penguins and increases in chinstrap penguins following winters with low sea ice in the South Shetland Islands during the 1970s and 1980s (1). However there now is overwhelming evidence that, in contrast to expectations, both Adélie and chinstrap penguin populations are declining throughout the WAP and broader Scotia Sea region. Results and DiscussionAdélie and chinstrap penguin populations have declined more than 50% during the last 30 y at study colonies in the South Shetland Islands (Fig. 1A). Moreover, since 1987, interannual changes in Adélie and chinstrap breeding populations have been positively correlated (Pearson's r = 0.7; P < 0.001; n = 21; Fig. 1B). T...

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Section: Resultsmentioning

confidence: 99%

Variability in krill biomass links harvesting and climate warming to penguin population changes in Antarctica

Trivelpiece

Hinke

Miller

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

366

432

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show abstract

“…These species utilize similar nesting habitats, have similar breeding schedules and both consume Antarctic krill Euphausia superba, which can dominate their diets (Trivelpiece et al 1987, Miller et al 2010. In addition, their foraging ranges are locally constrained during the chick-rearing period, as parents feed their chicks on a daily basis (Trivelpiece et al 1987).…”

Section: Open Pen Access Ccessmentioning

confidence: 99%

“…In addition, their foraging ranges are locally constrained during the chick-rearing period, as parents feed their chicks on a daily basis (Trivelpiece et al 1987). While the potential for competition is therefore clearly evident, past studies using stomach contents and animal tracking suggest that differences in diet and foraging habitat during the breeding season can lead to niche partitioning in Pygoscelis penguins (Trivelpiece et al 1987, Miller et al 2010, Wilson 2010. Having a clear understanding of patterns of niche segregation among Pygoscelis penguins is of increased importance because of recent climate-driven reductions in Antarctic krill in the Antarctic Peninsula region (Atkinson et al 2004, Ducklow et al 2007.…”

Section: Open Pen Access Ccessmentioning

confidence: 99%

“…Stomach content analysis is one of the most common methods for dietary analysis and has been used in previous studies of the diet and foraging ecology of sympatric Pygoscelis penguins (Trivelpiece et al 1987, Miller et al 2010. However, stomach content data reflect a 'snapshot' of recent diet and can be highly variable while underestimating the im portance of soft-bodied prey, such as fish and squid (Barrett et al 2007).…”

Section: Open Pen Access Ccessmentioning

confidence: 99%

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Contrasting specialist and generalist patterns facilitate foraging niche partitioning in sympatric populations of Pygoscelis penguins

Polito

Trivelpiece²,

Patterson³

et al. 2015

Mar. Ecol. Prog. Ser.

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“…In most cases, ecological segregation occurs by spatial separation of the foraging habitats as inferred from direct observation, diet analysis, stable isotope analysis, satellite telemetry, or a combination of these methods. This has been demonstrated in giant petrels (González-Solís et al 2000), diving petrels (Bocher et al 2000), albatrosses (Cherel et al 2002b, Hyrenbach et al 2002, Pinaud & Weimerskirch 2007, penguins (Mori & Boyd 2004, Miller et al 2010, Wilson 2010, and temperate gulls (Kubetzki & Garthe 2003). Conversely, other studies have revealed important overlap in diet or foraging habitats of closely related species (prions; Cherel et al 2002a, cormorants;Sapoznikow & Quintana 2003), suggesting either non-limiting food resources, active interspecific competition for resources, or a limited diversity of prey (Diamond 1983).…”

Section: Introductionmentioning

confidence: 95%

Variability of resource partitioning in sympatric tropical boobies

Kappes¹,

Weimerskirch²,

Pinaud³

et al. 2011

Mar. Ecol. Prog. Ser.

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Inter-and intraspecific competition can lead to resource partitioning in sympatric species, processes likely affected by environmental productivity and population size. We investigated the foraging behaviour and diet of masked (Sula dactylatra) and red-footed (S. sula) boobies at Tromelin Island, western Indian Ocean, to examine the role of resource partitioning in the foraging strategies of these sympatric species in an extreme oligotrophic environment. We compared our results to published studies with differing environmental conditions or population sizes. We used GPS loggers and Argos transmitters to track foraging movements and used time-depth recorders to estimate dive depths. Masked boobies travelled further and at faster rates than redfooted boobies, and sexes did not differ in foraging behaviour. Based on randomization tests, the foraging range of each species (95% utilization distribution; UD) overlapped significantly. However, at core foraging areas (50% and 25% UD), interspecific segregation was greater than expected by chance alone. No intraspecific spatial segregation was detected between sexes. Environmental characteristics of area-restricted search zones differed between species, but not sexes; masked boobies utilized warmer, deeper, and less windy oceanic environments than red-footed boobies. Masked boobies attained greater diving depths than red-footed boobies and consumed primarily flying fish, whereas red-footed boobies consumed mostly squid. Red-footed and masked boobies breeding in the extreme oligotrophic environment near Tromelin demonstrated greater dietary partitioning differences in foraging ranges compared to a less oligotrophic environment. This suggests that environmental productivity may play a role in processes of resource partitioning in these sympatric species.KEY WORDS: Resource partitioning · GPS · Satellite tracking · Area-restricted search · Diet · Sula dactylatra · Sula sula Resale or republication not permitted without written consent of the publisher

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Foraging-Niche Separation of Breeding Gentoo and Chinstrap Penguins, South Shetland Islands, Antarctica

Cited by 70 publications

References 38 publications

Variability in krill biomass links harvesting and climate warming to penguin population changes in Antarctica

Variability in krill biomass links harvesting and climate warming to penguin population changes in Antarctica

Contrasting specialist and generalist patterns facilitate foraging niche partitioning in sympatric populations of Pygoscelis penguins

Variability of resource partitioning in sympatric tropical boobies

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