First exploration of the feeding areas of Brown Skua (Catharacta antarctica) during incubation at Islas Blancas, Chubut.

DIEGO MONTALTI; NICOLÁS SUÁREZ; PABLO YORIO; SOFIA COPELLO; PICHEGRU LORIEN; JUAN PABLO SECO PON

PUERTO IGUAZU

Congreso; Ornithological Congress of the Americas (XVII RAO/XXIV CBO/XCV AFO).; 2017

AVES ARGENTINAS

The Brown Skua occupies an important position in the marine ecosystem, functioning like opportunistic predator, scavenger and kleptoparasite. To date, very little information is know on its trophic ecology on the Patagonian coast. To evaluate the patterns of use of feeding areas in the incubation period, a total of 10 GPS loggers were deployed on breeding adults during 2016 breeding season. A total of 104 feeding trips were recorded, 70% of which were performed in daylight hours. On average each bird performed 2 trips per day (range: 1-5). The average distance traveled in the feeding trips was 44.5 ± 36.4 km (range: 0.7-472.0), with an average duration of 110 ± 67 minutes. The feeding areas were located at 13 ± 10 km on average from the nest, all located in the sea and mainly to the east of the colony. The total feeding area used by the skuas to feed was 1173 km2. This is the first work on the spatial ecology of skuas in Patagonia and shows that at least in incubation and area of study, the Brown Skuas obtain their food from the sea. These results show the importance of the waters surrounding the colony in the trophic ecology of the species and suggest the need for new studies to evaluate if the Brown Skuas maintain this feeding strategy in other stages of the reproductive cycle.