Public information facilitates habitat selection of a territorial species: the eastern kingbird

The study of breeding habitat selection has focused mainly on physical characteristics of the environment such as nest sites and food abundance, both of which are required for successful reproduction. However, individuals may have limited time to make settlement decisions, and thus, their knowledge of resource availability may be incomplete. Furthermore, food abundance during settlement may not reflect levels later in the breeding season. An alternative perspective is that the most direct measure of habitat suitability is derived from social information such as the presence of conspecifics (conspecific attraction) or their reproductive performance (habitat copying). We tested resource and socially based hypotheses of habitat selection in a population of eastern kingbirds, Tyrannus tyrannus, at Malheur National Wildlife Refuge in southeastern Oregon, U.S.A. Kingbirds nested in areas with a greater proportion of suitable nest trees than what was generally available, but many areas with suitable numbers of trees went unused. Kingbirds also settled in areas of relatively high insect abundance, but only in years when overall abundance was low. We also found support for the socially based hypotheses. Relative to where they nested previously, kingbirds tended to settle in areas of higher conspecific density. But, we found stronger evidence in favour of habitat copying, suggesting that dispersing individuals settled in areas that produced more fledglings in the previous year. Kingbirds thus appeared to select breeding habitat based, in part, on resource availability, but dispersal decisions may be influenced by social information, primarily past reproductive success of conspecifics.