| Avian distribution and population dynamics are partly determined by how individuals choose nest-sites and their resulting survival and reproduction at those nest-sites. I studied a marked population of Mountain Bluebirds in western Montana between 2000 and 2003. All birds nested in boxes in one of five habitat types: (1) irrigated croplands; (2) non-native grasslands; (3) sagebrush; (4) forests that had recently undergone stand-replacing fire; and (5) forests that had recently undergone stand-replacing fire and were subsequently salvage logged. I examined factors governing reproductive success, survival, and nest-site selection, to address different models of nest-site selection while accounting for scale.; Female bluebirds in post-fire habitat types have lower nest survival, a lower probability of fledging at least one nest, and a smaller number of nestlings compared to bluebirds breeding in non-forested habitat types. Females have fewer nestlings in post-fire habitats because of nest predation and a shorter nesting season due to forested habitats occurring at higher elevations, where snow pack is more persistent.; I investigated the role of geographic scale (i.e., size of study area) in the estimation of apparent survival by sampling scales between 0 and 40 km from previously used nests boxes, where the 0 km scale represents returning to a specific nest box. For hatch-year birds, apparent survival was asymptotic at 20 or 30 km and was time invariant. In contrast, apparent survival for after-hatch-year birds usually asymptotes within 1 km, but was time dependent.; Female bluebirds dispersed longer distances than males, and dispersal distance increased as individuals fledged fewer young during the previous nest attempt. The probability of a box being selected declined with distance for all age/sex classes. In addition, the probability of box selection increased with conspecific density for hatch-year females. For after-hatch-year females, the probability of a box being selected increased with conspecific density and reproductive success.; Combining estimates of reproduction and survival, I find it unlikely that birds nesting in post-fire habitats are able to replace themselves. Because few birds moved between post-fire and non-forested habitats, I could not determine if post-fire habitats are sinks or ecological traps. |
