Date of this Version
Waterbirds 33(2): 221-227, 2010
Few studies have investigated the use of aquaculture-produced foods by piscivorous birds. American White Pelicans (Pelecanus erythrorhynchos) were collected from four locations (two aquaculture, one riverine and one coastal) in the southeastern United States during winter and spring 1998-1999 to assess the contribution (biomass, frequency of occurrence) of aquaculture-produced foods and their effect on body condition. Pelican diets reflected opportunistic foraging across locations. Diet near catfish ponds consisted mostly of Channel Catfish (Ictalurus punctatus). Diets along the Mississippi River had similarly high biomass of catfish, but otolith counts suggested lower use of catfish. Diets near crawfish (Procambarus spp.) ponds included shad (Dorsomis spp.), crawfish and sunfish (Lepomis spp.); whereas diets from coastal Louisiana were predominantly salt water fish. Pelican body condition, as indexed by percent omental fat, was similar between seasons but higher at catfish ponds. Foraging at crawfish ponds did not improve body condition over foraging in natural conditions. The superabundant, large and vulnerable food source (i.e. catfish in aquaculture ponds) likely resulted in reduced energy expenditures by pelicans, which would improve body condition. Higher fat reserves could facilitate spring migration and reproductive success. American White Pelican use of catfish at aquaculture facilities is predicted to continue and likely increase.