Moult habitat, pre- and post-moult diet and post-moult travel of Ross Sea emperor penguins (original) (raw)
Related papers
Moult of the emperor penguin: travel, location, and habitat selection
Marine Ecology Progress Series, 2000
All penguins except emperors Aptenodytes forsteri and Adelies Pygoscelis adeliae moult on land, usually near the breeding colonies. These 2 Antarctic species typically moult somewhere in the pack-ice. Emperor penguins begin their moult in early summer when the pack-ice cover of the Antarctic Ocean is receding. The origin of the few moulting birds seen by observers on passing ships is unknown, and the locations are often far from any known colonies. We attached satellite transmitters to 12 breeding adult A. forsteri from western Ross Sea colonies before they departed the colony for the last time before moulting. In addition, we surveyed some remote areas of the Weddell Sea north and east of some large colonies that are located along the southern and western borders of this sea. The tracked birds moved at a rate of nearly 50 km d -1 for more than 1000 km over 30 d to reach areas of perennially consistent pack-ice. Almost all birds traveled to the eastern Ross Sea and western Amundsen Sea. Sea-ice conditions were observed directly in the Weddell Sea from ship and helicopter. Most floes selected for moulting were ridged, and usually >100 m 2 . From these observations we predict where the most likely moult refuges are for emperor penguins from other colonies around the Antarctic continent.
The winter migration of Adelie penguins breeding in the Ross Sea sector of Antarctica
Polar Biology, 2001
Satellite telemetry was used to monitor the migratory movements of a single Adelie penguin (Pygoscelis adeliae) from Cape Hallett (72.31°S, 170.21°E) following the 1997/1998 breeding season. Locations were obtained using the ARGOS satellite system and compared with the migratory paths taken by two penguins from the Northern Colony at Cape Bird, Ross Island (77.22°S, 166.48°E) following the 1990/1991 breeding season. Although the sample sizes are small, if representative they would indicate that: (1) Adelie penguins breeding in the Ross Sea follow a common migratory path, (2) Adelie penguins breeding in the Ross Sea may travel to a common over-winter feeding ground west and north of the Balleny Islands, and (3) Adelie penguins breeding at 77°S on Ross Island travel nearly twice the distance during their over-winter migration as do those penguins breeding at Cape Hallett and colonies further north. While the Cape Hallett penguin was tracked successfully for 172 days, a record for Adelie penguins, the problem of long-term attachment of transmitters to penguins remains.
Analyses of the body masses of Ade lie penguins (Pygoscelis adeliae) departing on foraging trips of long and short duration (> and<40 h, respectively) during chick rearing showed that the departure weights of birds prior to long trips were signi®cantly lighter than were those prior to short trips. Penguins, particularly males, were signi®cantly heavier at the start of the guard stage than at the end and both sexes gained similar amounts of body mass during the creÁ che period. Results support the hypothesis that the foraging eort of Ade lie penguins at Be chervaise Island is partitioned between the sexes, with males accepting a net rate of negative energy gain to provide regular meals for their ospring during the guard stage. Ade lie penguin foraging behaviour may be driven by a trade-o between the allocation of food to chicks and the storage of parental body reserves, similar to that previously postulated for some species of¯ying seabirds. The relevance of such a foraging strategy to the breeding success of penguins in the Mawson region of eastern Antarctica is discussed in relation to micronekton distribution in the area.
Deep Sea Research Part II: Topical Studies in Oceanography, 2011
In accord with the hypotheses driving the Southern Ocean Global Ocean Ecosystems Dynamics (SO GLOBEC) program, we tested the hypothesis that the winter foraging ecology of a major top predator in waters off the Western Antarctic Peninsula (WAP), the Adé lie penguin (Pygoscelis adeliae), is constrained by oceanographic features related to the physiography of the region. This hypothesis grew from the supposition that breeding colonies in the WAP during summer are located adjacent to areas of complex bathymetry where circulation and upwelling processes appear to ensure predictable food resources. Therefore, we tested the additional hypothesis that these areas continue to contribute to the foraging strategy of this species throughout the non-breeding winter season. We used satellite telemetry data collected as part of the SO GLOBEC program during the austral winters of 2001 and 2002 to characterize individual penguin foraging locations in relation to bathymetry, sea ice variability within the pack ice, and wind velocity and divergence (as a proxy for potential areas with cracks and leads). We also explored differences between males and females in core foraging area overlap. Ocean depth was the most influential variable in the determination of foraging location, with most birds focusing their effort on shallow (o 200 m) waters near land and on mixed-layer (200-500 m) waters near the edge of deep troughs. Within-ice variability and wind (as a proxy for potential areas with cracks and leads) were not found to be influential variables, which is likely because of the low resolution satellite imagery and model outputs that were available. Throughout the study period, all individuals maintained a core foraging area separated from other individuals with very little overlap. However, from a year with light sea ice to one with heavy ice cover (2001)(2002), we observed an increase in the overlap of individual female foraging areas with those of other birds, likely due to restricted access to the water column, reduced prey abundance, or higher prey concentration. Male birds maintained separate core foraging areas with the same small amount of overlap, showing no difference in overlap between the years. While complex bathymetry was an important physical variable influencing the Adé lie penguin's foraging, the analysis of sea ice data of a higher resolution than was available for this study may help elucidate the role of sea ice in affecting Adé lie penguin winter foraging behavior within the pack ice.
Polar Biology, 1995
The diet of emperor penguins Aptenodytes forsteri was studied during late austral summer at Drescher Inlet, eastern Weddell Sea, Antarctica. Antarctic krill Euphausia superba was a major component of the food, accounting for 75% of all prey items. Emperor penguins appear to feed on krill during shallow dives under the fast sea ice. Fish, mainly nototheniids, accounted for less than 20% by number of all prey. An evaluation of the main prey types in terms of mass indicated, however, that fish represented up to 75% approximately of prey mass. Feeding experiments were performed on captive penguins and showed that squid beaks can accumulate for up to 3 weeks within the stomach without any clear signs of erosion. The lack of cephalopod soft parts in the samples makes it likely that all squid beaks were derived from animals captured some time previously. Squid seems to be a very minor dietary component of emperor penguins at the Drescher Inlet.
Marine Ecology Progress Series, 1997
Mle lnvestlgated the foraging behaviour of king pengulns In relation to sea-surface temperature distribution over 3 years near the Crozet Archipelago, South Indlan Ocean. Wlthln their range there are 2 hydrographlc frontaI systems, whose seasonal patterns of productivity are predictable. These are the Polar Front and the Sub-Antarctic Front. During the austral summer the foraging range of breeding king pengulns was restricted to the Polar Frontal Zone, limlted to the south by the Polar Front and to the north by the Sub-Antarctic Front. Most b~r d s travelled towards the colder water situated south of Crozet, w h~l e other birds moved east to warmer water Blrds travelling south spent more time than expected in the coldest waters generally associated with the Polar Front. Birds travelling east reached the southern limit of the Sub-Antarctic Front (sea-surface temperature between 8 and 10°C). Within the Polar Frontal Zone birds differed In their foraging behaviour, with incubating birds remaining at sea for longer times and covering longer distances. During the incubation period, king penguins travelling south tended to spend their time in areas with a sea-surface temperature between 4 and 5°C. which coincide with the location of the Polar Front. Though these birds remained a t sea longer, they did not go any further south than birds hilv~ng a n egg ready to hatch or than birds in the brooding period, which appeared to travel more directly towards the Polar Front. As the breeding season progressed, the Polar Front moved further south, out of the range of the king penguins espcc~ally those with a newly hatched c h~c k that were limited in the amount of time that they could spend at sea. King penguins breeding a t Crozet may choose between 2 strategies, in w h~c h some blrds forage towards the Sub-Antarctic Front but most travel south towards the Polar Front. KEY WORDS. Sea-surface temperature King penguins Southel-n Ocean Foraging Biotelemetry Remote sensing
2009
FACTORS AFFECTING ADULT FORAGING AND CHICK GROWTH OF ADÉLIE PENGUINS (PYGOSCELIS ADELIAE ) OFF THE WESTERN ANTARCTIC PENINSULA: A MODELING STUDY Erik W. Chapman Old Dominion University, 2009 Director: Dr. Eileen E. Hofmann Coupled individual-based models that simulate Adélie penguin (Pygoscelis adeliae) adult foraging behavior and chick growth from hatching to fledging were developed and used to explore factors that influence adult foraging energetics and chick fledging mass off the western Antarctic Peninsula (WAP). Adélie penguin colonies in this region are undergoing changes in population size that have been correlated with climate-driven alteration of the marine environment. Simulations were selected to highlight possible linkages between these population changes and climate variability, adult foraging, and chick growth processes. Simulations using the chick-growth model tested the influence on penguin chick fledging mass of variability in 1) timing of Antarctic krill (Euphausia...
Deep Sea Research Part II: Topical Studies in Oceanography, 2000
The foraging behaviour of AdeH lie penguins Pygoscelis adeliae was studied simultaneously at Shirley Island (SI, 1103E) and at Petrel Island (PI, 1403E) in approximate conjunction with the ship-based krill survey conducted on board the RSV Aurora Australis. Acoustic and trawl data were collected near both study sites, albeit at the end of the penguins' breeding season. The distances travelled by AdeH lie penguins from Shirley Island were signi"cantly greater than those travelled by penguins from Petrel Island (SI 31}144 km; PI 6}79 km). Mean foraging trip durations and mean maximal distances travelled were also signi"cantly di!erent between colonies (duration: SI guard
SPATIAL AND TEMPORAL VARIATION OF DIET WITHIN A PRESUMED METAPOPULATION OF ADÉLIE PENGUINS
The Condor, 2003
We investigated temporal and spatial variability in the diet of chick-provisioning Adélie Penguins (Pygoscelis adeliae) breeding at all colonies within one isolated cluster in the southwestern Ross Sea, Antarctica, 1994Antarctica, -2000. We wished to determine if prey quality explained different population growth and emigration rates among colonies. Diet composition was described both by conventional means (stomach samples) and by analysis of stable isotopes in chick tissues (toenails of individuals killed by skuas [Stercorarius maccormicki]). Diets were similar among the four study colonies compared to the disparity apparent among 14 widely spaced sites around the continent. Calorimetry indicated that fish are more energetically valuable than krill, implying that if diet varied by colony, diet quality could attract recruits and help to explain differential rates of colony growth. However, a multiple-regression analysis indicated that diet varied as a function of year, time within the year, and percent of foraging area covered by sea ice, but not by colony location. Stable isotopes revealed similarity of diet at one colony where conventional sampling was not possible. We confirmed that sea ice importantly affects diet composition of this species in neritic waters, and found that (1) quality of summer diet cannot explain different population growth rates among colonies, and (2) stable isotope analysis of chick tissues (toenails) is a useful tool to synoptically describe diet in this species over a large area.
Utilisation of the oceanic habitat by king penguins over the annual cycle
Marine Ecology Progress Series, 2001
The distribution and behaviour of foraging seabirds depend on the physical features of the ocean at different time and space scales, but little is known for penguins. We investigated the foraging behaviour of king penguins in relation to oceanographic features over the birds' complete annual cycle. A total of 44 birds was followed between 1994 and 1997 at the Crozet Islands to monitor foraging habitat, diving behaviour, and sea temperature of the water column, using satellitetracking and time-temperature-depth recorders (TDR) carried by the birds. The study included breeding in summer, the winter period of chick raising, and the post-moult period in spring. King penguins foraged in 2 specific regions in response to the seasonal changes in local prey availability. In summer, satellite-tracked birds during the incubating and brooding stages (n = 14) preferentially exploited the polar front located 340 to 450 km to the south of their breeding site. TDR-equipped birds (n = 12) also foraged at the polar front in summer as indicated by the vertical temperature profiles. In autumn and winter, satellite tracks (n = 8) and sea temperature measurements of TDRequipped birds (n = 8) showed that birds with crèching chicks instead foraged in antarctic waters, with 70% of individuals reaching the latitude of the pack-ice limit (1600 km from the colony). This suggests better prey availability than in the polar frontal zone at that time. When the birds were at the latitude of the polar front, the thickness of the surface mixed layer (SML) ranged from 80 m in summer to 140 m in winter, the SML temperature was ~4°C and the thermocline had a mean maximum gradient of-0.5°C for each 10 m depth. When the birds were at their most southerly position, the depth of the SML ranged from 100 m in autumn to ~150 m in winter, while its temperature ranged from-0.8 to 2°C. The temperature gradient of the thermocline showed an inversion in autumn, and this gradient was positive in winter (mean maximum gradient of 0.3°C for each 10 m depth). Except for spring birds (n = 4) and for 1 winter bird, where the SML exceeded the diving range, all TDRequipped penguins (n = 19) dived preferentially in and below the depth of the thermocline, thereby minimising diving in the SML. Therefore, their prey may have been predictably concentrated below the SML through oceanographic processes. In king penguins, the strategy of going south could then have evolved in relation to the thinning of the SML towards the south at any time of the year.