Diving and foraging behaviour of Adélie penguins in areas with and without fast sea-ice

Abstract

The diving and foraging behaviours of Ade´lie penguins, Pygoscelis adeliae, rearing chicks at Hukuro Cove, Lu¨tzow-Holm Bay, where the fast sea-ice remained throughout summer, were compared to those of penguins at Magnetic Island, Prydz Bay, where the fast sea-ice disappeared in early January. Parent penguins at Hukuro Cove made shallower (7.1-11.3 m) but longer (90-111 s) dives than those at Magnetic Island (22.9 m and 62 s). Dive duration correlated with dive depth at both colonies (r"0.01&0.90), but the penguins at Hukuro Cove made longer dives for a given depth. Parents at Hukuro Cove made shorter foraging trips (8.1-14.4 h) with proportionally longer walking/swimming (diving (1 m) travel time (27-40% of trip duration) and returned with smaller meals (253-293 g) than those at Magnetic Island, which foraged on average for 57.2 h, spent 2% of time walking/swimming ((1 m) travel, and with meals averaging 525 g. Trip duration at both colonies correlated to the total time spent diving. Trip duration at Hukuro Cove, but not at Magnetic Island, increased as walking/swimming ((1 m) travel time increased. These differences in foraging behaviour between colonies probably reflected differences in sea-ice cover and the availability of foraging sites.

Trophic cascades in the western Ross Sea, Antarctica: revisited

“…In one subcolony, where foraging trip duration was measured using a weighbridge as described below, among 22 monitored nests (al most all members with radio frequency ID [RFID] tags), there were no chicks in the crèche stage on 10, 15, 20, and 25 December, but by 31 December, 5 January, and 10 January, respectively, 5, 28, and 86% of nests had chicks in crèches. Adélie penguins forage by diving, mostly at depths ≤50 m but to a maximum of ~175 m (Whitehead 1989, Watanuki et al 1997, Ainley & Ballard 2011. During the study period, we equipped 46 adult birds, each having at least one chick, with 'Splash' tags (Wildlife Computers) that measure diving behavior as well as location.…”

Foraging under contrasting oceanographic conditions: the gentoo penguin at Kerguelen Archipelago

“…The Open Sea 1 colony faced the large Kerguelen shelf, and the proximity of the Polar Front allowed the penguins access to a large area of particularly productive shallow, neritic waters (Blain et al 2001). According to the central place foraging theory (Orians & Pearson 1979), birds would perform longer trips and return with larger meals when food is abundant (Watanuki et al 1997). The shorter trips at Closed Sea are halfway between those exhibited at the northern and southern localities.…”

Late-Holocene initiation of ice-free ecosystems in the southern Ross Sea, Antarctica

“…Over 744 000 breeding pairs, or 30% of the world population, occur on the Victoria Land Coast bordering the Ross Sea , one of the southernmost marine ecosystems on Earth. Adélie penguins require open water near their breeding colonies, with no more than 2 to 3 km of persistent fast ice that must be crossed on foot to reach ice-free terrain; any additional fast ice, especially lacking tide cracks associated with grounded icebergs, and colonies are very small or absent (Watanuki et al 1997. All extant colonies on Ross Island (see Fig.…”