MEPS 614:183-197 (2019)  -  DOI: https://doi.org/10.3354/meps12910

ABSTRACT: Breeding in most species is timed to coincide with the greatest availability of food resources to support the increased energetic needs of reproduction. Correspondingly, the majority (76%) of seabird species in temperate and polar regions breed in spring/summer, matching the peak in ocean productivity. The Fiordland penguin Eudyptes pachyrhynchus is one of only 34 seabird species worldwide that have part of their breeding cycle during the winter, and its chicks fledge when the eggs of congeneric Eudyptes species in the same region are only starting to hatch. Little is known of the foraging ecology of this species and the factors that may influence its timing of breeding. In the present study, the foraging behaviour of breeding individuals from Taumaka/Open Bay Island, New Zealand, was investigated using GPS, dive recorder and tri-axis accelerometer data loggers. In total, 35 individuals (4 males, 31 females) were tracked at sea, revealing extensive use of continental shelf slope (200-1000 m) habitat within 42 ± 5 km of the colony. Individuals foraged mostly during daylight in the epi-pelagic zone (mean modal depth 22 ± 2 m) and prey encounter events occurred in 50% of dives. Blood isotopic signatures suggest a trophic level indicative of squid consumption, supporting previous findings that winter-spawning squid are the most important prey type. The results of the present study suggest that a winter-breeding strategy by seabirds can reflect locally abundant prey resources and suitable conditions at the time for breeding.

KEY WORDS: Foraging behaviour · Winter breeding · Bio-logging · Prey encounter · Eudyptes pachyrhynchus · New Zealand