Trophic ecology of breeding White-headed Steamer-Duck

AGUERO, LAURA; GARCÍA BORBOROGLU, PABLO; ESLER, DANIEL

WATERBIRDS (DE LEON SPRINGS, FLA.)

WATERBIRD SOC

Año: 2014 vol. 37 p. 88 - 93

1524-4695

This study provides the first detailed information on Chubut Steamerduck?s (Tachyeres leucocephalus) feeding territories, prey availability, diet composition, and foraging behavior. We conducted our study from October to December 2007 in the northern San Jorge Gulf, Patagonia, Argentina. We identified 15 feeding territories and quantified food availability in territories and unused areas. We analyzed 45 feces from 15 nests to determine diet composition and monitored the foraging behavior of 29 females. Benthic prey availability differed between territories and non-territories. Mollusks like little mussels (Perumytilus purpuratus) and bivalves (Lasaea spp), and crustaceans Tanaidacea, isopods, and crabs (Cyrtograpsus spp.) were the most abundant taxa in territories, accounting for 97.4% of the total fauna, whereas non-territories had lower diversity and 97.2% of the total fauna were represented by Perumytilus purpuratus, Lasaea spp. and isopods. Ten invertebrate prey taxa were identified in adult diets, and the most frequent prey in feces were crabs (Cyrtograpsus spp.), mussels (Mitilidae), and ragworms (Nereidiidae). Head-neck dipping was the most common method of feeding followed by filtering, diving, and up-ending. Our results improve the understanding about the relationship between the feeding requirements, the selection and defense of areas with special food availability and the foraging techniques used to access and exploit the resources.