Dynamic versus static occupancy: How stable are habitat associations through a breeding season?

Abstract

Most studies of habitat use by animals assume that there is little movement by individuals once they have settled. This assumption of static occupancy is especially true in studies of birds, even though many bird species are known to abandon failed nest sites in search of better habitat or to move up a habitat gradient as the season proceeds. If birds move into different habitats as the season progresses, studies assuming static use of habitat may provide misleading or incomplete inference into habitat use. We tested the hypothesis that birds use different habitats as the breeding season progresses by analyzing point counts conducted early and late in the breeding season within Tuskegee National Forest, AL. For 15 species of conservation concern, we compared models that assumed static occupancy with models that estimated apparent movement between early and late‐season surveys. Models that estimated movement outcompeted static models for every species. Furthermore, patterns of movement provided inference that would not have been gained through a static modeling approach, with species moving into habitats traditionally known to be of high quality, and moving out of those assumed to be of poor quality. Our results suggest that studies of habitat use would benefit from estimating movement within a season.