Diet and Foraging

Brazilian Mergansers feed basically on small fish they capture during dives, although aquatic macroinvertebrates also contribute to their diet. Very often, before diving, they search for their prey swimming with just their heads submerged. Dives can last 15 to 20 seconds (Hughes et al. 2006), and even 30 seconds in deeper pools. We have observed them catching insects flying around their heads. In the Serra da Canastra region, the most common fish species which serve as their food are “lambaris” (Astyanax spp.) and “barrigudinho” (Phalloceros caudimaculatus). Stomach content analysis of individuals from Misiones, Argentina, showed they ate lambaris (Characidae), ciclids, catfish (Pimelodidae), “virolito” (Parodon affinis), larvae of Dobson flies (Corydalis sp.) and, probably, molluscs (Partridge 1956).