Ovenbird (Aves: Parulidae) hunting behavior in a patchy environment: an experimental study

Abstract

We investigated the foraging behavior of ovenbirds (Seiurus aurocapillus) in a patchy food supply. Nine birds were individually exposed on 2 successive days to four patches of 1.5 × 1.5 m containing 2, 4, 8, and 16 prey, respectively, in a 6 × 6 m field arena. Patch locations were kept constant; however, prey densities were interchanged on day 2.Amount of search path in patches increased exponentially with prey density. Birds rapidly shifted their search effort when prey densities were interchanged. Differential distribution of search effort resulted from more visits and greater search path per visit, owing to greater tortuosity of the search path in denser patches. Since less search path was required per prey found in denser patches, the search effort was concentrated in areas of high profitability and the birds took a higher percentage of prey available in these patches. However, in comparison with a simple model, their foraging among patches was suboptimal, except in the final period of day 1. Birds tended to avoid some recently visited patches although the overall sequence of visits to the four patches was random.It is proposed that differences in renewal and depletion rates of prey are important determinants of foraging behavior of ovenbirds and other species feeding in patchy environments.