Geology topics

Amelie Lescroël

Publications and source records attributed to Amelie Lescroël.

3 recordsLinked to original sources

USGS2024

Going with the floe: Sea-ice movement affects distance and destination during Adélie penguin winter movements

Seasonal migration, driven by shifts in annual climate cycles and resources, is a key part of the life history and ecology of species across taxonomic groups. By influencing the amount of energy needed to move, external forces such as wind and ocean currents are often key drivers of migratory pathways exposing individuals to varying resources, environmental conditions, and competition pressures impacting individual fitness and population dynamics. Although wildlife movements in connection with wind and ocean currents are relatively well understood, movements within sea-ice fields have been much less studied, despite sea ice being an integral part of polar ecology. Adélie penguins ( Pygoscelis adeliae ) in the southern Ross Sea, Antarctica, currently exist at the southernmost edge of their range and undergo the longest (~12,000 km) winter migration known for the species. Within and north of the Ross Sea, the Ross Gyre drives ocean circulation and the large-scale movement of sea ice. We used remotely sensed sea-ice movement data together with geolocation-based penguin movement data to test the hypothesis that penguins use gyre-driven sea-ice movement to aid their migration. We found that penguins traveled greater distances when their movement vectors were aligned with those of sea ice (i.e., ice support) and the amount of ice support received depended on which route a penguin took. We also found that birds that took an eastern route traveled significantly further north in two of the 3 years we examined, coinciding with higher velocities of sea ice in those years. We compare our findings to patterns observed in migrating species that utilize air or water currents for their travel and with other studies showing the importance of ocean/sea-ice circulation patterns to wildlife movement and life history patterns within the Ross Sea. Changes in sea ice may have consequences not only for energy expenditure but, by altering migration and movement pathways, to the ecological interactions that exist in this region.

Ecology↗

USGS2020

Inter-individual differences in the foraging behavior of breeding Adélie penguins are driven by individual quality and sex

Inter-individual differences in demographic traits of iteroparous species can arise through learning and maturation, as well as from permanent differences in individual ‘quality’ and sex-specific constraints. As the ability to acquire energy determines the resources an individual can allocate to reproduction and self-maintenance, foraging behavior is a key trait to study to better understand the mechanisms underlying these differences. So far, most seabird studies have focused on the effect of maturation and learning processes on foraging performance, while only a few have included measures of individual quality. Here, we investigated the effects of age, breeding experience, sex, and individual breeding quality on the foraging behavior and location of 83 known-age Adélie penguins at Cape Bird, Ross Sea, Antarctica. Over a 2 yr period, we showed that (1) high-quality birds dived deeper than lower quality ones, apparently catching a higher number of prey per dive and targeting different foraging locations; (2) females performed longer foraging trips and a higher number of dives compared to males; (3) there were no significant age-related differences in foraging behavior; and (4) breeding experience had a weak influence on foraging behavior. We suggest that high-quality individuals have higher physiological ability, enabling them to dive deeper and forage more effectively. Further inquiry should focus on determining the physiological differences among penguins of different quality.

MEPS↗

USGS2018

Post-fledging survival of Adélie Penguins at multiple colonies: chicks raised on fish do well

We assessed whether the mass of Adélie penguin Pygoscelis adeliae fledglings at 3 colonies of markedly disparate size on Ross Island, Ross Sea, correlated with their eventual return as subadults. We compared our results with those from Anvers Island, Bellingshausen Sea. Colony sizes at Ross Island have been increasing, contrary to decreasing size at Anvers Island. At Ross Island, during the month prior to fledging, chick diet consisted equally of energy-dense Antarctic silverfish Pleuragramma antarctica and less-caloric crystal krill Euphausia crystal-lorophias , while at Anvers Island the diet was principally Antarctic krill E. superba . At Ross Island, the mass of fledglings who subsequently returned (mean ± SE: 3.4 ± 0.0411 kg) exceeded that of those not seen again (3.2 ± 0.0251 kg), compared to Anvers Island (3.2 vs. 3.0 kg, respectively). At Ross Island, fledging mass was inversely related to colony size and, at the largest colony, fledging mass decreased as the colony grew. Average mass of returnees at the largest colony was less than the mass at Anvers Island for those fledglings that did not return. The mean proportion of fish in the chicks’ diet decreased at the largest Ross Island colony over time, as did fledging mass. We hypothesize that intraspecific competition increased along with colony size, decreasing the availability of fish. We further hypothesize that at the large Ross Island colony, post-fledging penguins must be finding adequate prey, and more energy-dense fish, just outside the colony’s foraging area to explain opposing trends in colony trajectories.

Beaufort Island, Ross Island, Ross Sea↗