Sex differences in habitat use and foraging behavior in the Southern Giant Petrel (Macronectes giganteus) at the Patagonian shelf.

COPELLO, S.; QUINTANA, F.

Barcelona, España

Congreso; 31st Annual Meeting of the Waterbird Society; 2007

Sexual segregation by foraging habitat is a relatively common characteristic of seabirds. We satellite-tracked seven males and nine females of Southern Giant Petrel from the two existing breeding sites of coastal Patagonia, Argentina. During late incubation and chick rearing periods, females used pelagic areas to a greater extent than males. Only females exploited a pelagic area in the shelf break.  Males explored mainly coastal areas which were located at a greater distance from the colony than those used by females. There was not differences in the maximum foraging range between genders (522 vs. 414 km, for females and males, respectively). The areas of use for both sexes were overlapped between 35 and 94%. Males utilized a greater proportion of the female areas. The foraging trip pattern was similar between sexes. The total distance covered in a single foraging trip extended between ten to more than 4000 km. However, for most of the trips, the total distance traveled was less than 200 km and between 55 and 83% of the trips did not exceed 400 km. Both sexes alternated long and short foraging trips. However, all females performed long trips while only half of the males did it. The remarkable spatial overlapped in foraging areas is probably linked with a low competition between sexes given the high availability and abundance of food sources in the Patagonian Shelf. Besides, the surplus of food from fisheries discards could play a key role diminishing the mechanisms that contribute to sexual segregation in habitat use.