Nest success and the timing of nest failure of Florida Scrub-Jays in suburban and wildland habitats

Abstract

Urbanization has broad and complex effects on ecological systems. Many of these effects are likely to influence nest success of birds, some positively and others negatively, thus complex interactions among effects are likely to exist that influence patterns of success. Nest success of Florida Scrub-Jays did not differ between a suburban and wildland population or across a human density gradient within the suburban population. Nesting success between egg and nestling stages did not differ in the wildland population, but nest success during the egg stage was high and success during the nestling stage low in the suburban population. As a consequence, nest contents survived longer during the nesting cycle in the suburban population than in the wildland population, even though overall rates of nest success did not differ. In the suburbs, nests with eggs were less likely to be deserted and nests with nestlings were more likely to be depredated or more likely for the nestling to starve than in the wildlands. In both habitats, nest success declined throughout the nesting season. Because suburban birds begin nesting earlier than wildland birds, nests are at a more advanced stage when nest failure rates increase. However, temporal differences in nesting are absent for second and third nest attempts, yet suburban nests still fail later in the nesting cycle. This suggests that site-specific differences exist in the predator community or the behavior of birds increasing their vulnerability to predators that affects timing of nest failure.