Road effects on food availability and energetic intake in florida scrub-jays (Aphelocoma coerulescens)

摘要

Roads may have detrimental effects on many bird species, but areas adjacent to roads also provide habitat and food for some species. To address the influence of roadside habitat on the federally threatened Florida Scrub-Jay (Aphelocoma coerulescens), we compared foraging effort, the amount of food collected, and estimated energy intake in three habitat types: (1) edges along a paved road (roadside), (2) edges created by human-maintained habitat without a road (pasture), and (3) natural scrub-dominated areas with minimal human-maintained edges (interior). We used focal watches of male breeders during three stages of the breeding season (incubation, nestling, and fledged young) in two consecutive years to assess variation in food availability and energetic intake among the three habitat types. Florida Scrub-Jays in roadside habitats handled (consumed, cached, or fed to their mate or offspring) significantly more food items and spent less time foraging during the nestling stage than interior and pasture jays, but no differences in handled food were found among the three habitat types during the incubation and fledgling stages. Although they spent less time foraging, roadside jays had higher rates of energy intake than interior and pasture jays during the incubation stage. There were no differences in these measures of foraging during the incubation, nestling, and fledgling stages between interior and pasture jays. Our results suggest that roads or roadside habitat, not simply edge habitats, have a positive effect on food availability and energy intake in Florida Scrub-Jays, although the patterns differ across breeding stages.