Foraging behaviour and habitat use of chick-rearing Australasian Gannets in New Zealand

Patchily distributed marine pelagic prey present considerable challenges to predatory seabirds, including Gannets (Morus spp.) departing from large breeding colonies. Here, for the first time, we used GPS data loggers to provide detailed spatial, temporal, and habitat metrics of chick-rearing Australasian Gannets (Morus serrator) foraging behaviours from two distant colonies in New Zealand. Our goal was to examine the extent to which Gannet foraging tactics vary across disparate habitats, and determine whether the observed differences are consistent with predictions derived from foraging studies of other gannet species. Foraging trip performance was highly consistent between colonies, and sexes, and no significant differences in any of the variables analyzed were observed. However, Gannets from Farewell Spit (FS) dove in shallower waters (0-50 m) than birds from Cape Kidnappers (CK, >50 m), which is consistent with previous dietary studies suggesting that FS Gannets feed mainly on coastal prey, whereas CK birds feed on species with a more oceanic distribution. Diving frequencies were similar in the two colonies suggesting that Gannets were foraging in habitats with similar levels of food availability. Further studies are needed to understand the relationship between prey availability, oceanography and geographic features, to better interpret foraging tactics of Australasian Gannets. © 2013 Dt. Ornithologen-Gesellschaft e.V.Fil: Machovsky-capuska, Gabriel. Massey University; Nueva Zelanda. University of Technology Sydney; AustraliaFil: Hauber, Mark E.. City University of New York. The City College of New York; Estados UnidosFil: Dassis, Mariela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Libby, Eric. Massey University; Nueva ZelandaFil: Wikelski, Martin C.. University Of Konstanz (university Of Konstanz); . Max-Planck Institute for Ornithology; AlemaniaFil: Schuckard, Rob. Ornithological Society of New Zealand; Nueva ZelandaFil: Melville, David S.. Ornithological Society of New Zealand; Nueva ZelandaFil: Cook, Willie. Ornithological Society of New Zealand; Nueva ZelandaFil: Houston, Michelle. Massey University; Nueva ZelandaFil: Raubenheimer, David. University of Technology Sydney; Australi