Effects of resource availability on foraging trip duration in the silver bee, Habropoda miserabilis

Habitat fragmentation can have negative effects throughout an ecosystem, but its impact is dependent on the spatial scale at which community members respond to the environment. Because solitary bees are central-place foragers, their access to floral resources is constrained by their nest location. Therefore, if habitat fragmentation causes the distance between nest and resource patches to be larger than the spatial scale at which a bee species interacts with its environment, bee fitness may suffer. I used foraging trip duration as a measure of bee response to differences in levels of resource availability at various spatial scales to determine the foraging range of the silver bee, Habropoda miserabilis. I timed 260 foraging trips and mapped pollen availability in the silver bee's habitat. The results suggest that the silver bee responds to its environment at a broad spatial scale. Several factors, including weather conditions and individual foraging ability, contribute to the complexity of the relationship between foraging trip duration and resource availability, but the silver bee seems to be unaffected by small-scale habitat variation. Because the silver bee can easily fly the width of its dune habitat, this bee may act as a "pollination bridge" between scattered patches of dune-mat vegetation, and is therefore critically important to the ecosystem's health, especially in light of increased habitat fragmentation inflicted on the dunes by invasive plant species.