Cognition and the brain of brood parasitic cowbirds.

Cowbirds are brood parasites. Females lay their eggs in the nests of other species, which then incubate the cowbird eggs and raise the young cowbirds. Finding and returning to heterospecific nests presents cowbirds with several cognitive challenges. In some species, such as brown-headed cowbirds (Molothrus ater), females but not males search for and remember the locations of potential host nests. We describe recent research on sex differences in cognition and the hippocampus associated with this sex difference in search for host nests. Female brown-headed cowbirds perform better than males on some, but not all, tests of spatial memory and females show a pattern of adult hippocampal neurogenesis not found in males or in closely related non-parasitic birds. Because of the apparent specialization of the hippocampus, brown-headed cowbirds may be a good model in which to examine spatial information processing in the avian hippocampus and we also describe recent research on the spatial response properties of brown-headed cowbird hippocampal neurons.