Life in an altered landscape: Reproductive success and foraging efficiency of Florida Scrub-Jays (Aphelocoma coerulescens) in regenerating pasture

摘要

The challenge of protecting habitat for imperiled species amidst continuing, excessive habitat alteration constrains our conventional definition of ?suitable? habitat. Certain endangered species are known to persist on modified habitat, especially where their native habitat is largely destroyed. I examined reproductive success and foraging efficiency of Florida Scrub-Jays (Aphelocoma coerulescens) in a human modified habitat ? regenerating pasture ? along a pasture-native scrub interface. From 1985 to 2003, Florida Scrub-Jays were equally successful at producing young in regenerating pasture and native scrub. Production of eggs, nestlings, fledglings, independent young, and yearlings per nest were not statistically different between pasture and scrub, but consistently trended higher in the former. Nest success in pasture was significantly higher among pairs lacking nonbreeding helpers compared to pairs with helpers. Breeding males preferred pasture for their overall daily activities, and foraged equally frequently in pasture and scrub. Foraging efficiency of breeding males was significantly higher for small prey items, but significantly lower for medium and large prey items when they foraged in pasture compared to when they foraged in scrub. Availability of small prey items was significantly higher in pasture than in scrub; the availability of medium and large prey items were not significantly different between habitat types. These results suggest that regenerating pasture can provide suitable habitat for Florida Scrub-Jays when in close proximity to native scrub. The definition of suitable habitat for this habitat-limited species should be expanded to include areas of pasture containing regenerating oak shrubs.