Habitat use and diving behaviour of macaroni Eudyptes chrysolophus and eastern rockhopper E. chrysocome filholi penguins during the critical pre-moult period
Résumé
After the breeding season, penguins must
replenish body condition and accumulate sufficient energy
stores before their annual moult ashore; failure to do so
may lead to starvation. Knowing where and how adult
penguins find adequate resources during this energy-intensive
stage is vital to understanding their susceptibility to
ecosystem changes. GPS and TDR loggers were used to
track movements and record diving behaviour of macaroni
Eudyptes chrysolophus and eastern rockhopper E. chrysocome
filholi penguins from Marion Island (46°S, 37°E)
during the pre-moult foraging trip in 2012, 2013 and 2014.
Both species consistently travelled in a southerly direction
to forage in cooler (~3.5 °C) Antarctic Zone waters south
of the Antarctic Polar Front where they associated with
mesoscale eddies and sub-mesoscale filaments. Dives were
predominantly to depths of 30 to 60 m, but macaroni penguins
dived deeper more often. Mean trip durations of both species were similar (33 ± 6 days), but maximum foraging
ranges of macaroni penguins (903 ± 165 km) were greater
than eastern rockhopper penguins (696 ± 152 km). Spatial
overlap of core foraging areas between species was high,
but a 2- to 3-week difference in departure dates reduced
potential interspecific competition at sea. Trip durations
were longer in 2014 compared to 2013, when decreased
productivity may have reduced prey availability, forcing
penguins to remain longer at sea. Continued monitoring is
vital to understand how crested penguins at Marion Island
adapt to the predicted southward shift of major frontal
boundaries.