Landscape patterns can influence seed survival and dispersal by altering the behavior of individual consumers and seed dispersers. Landscape-scale disturbances therefore have the potential to mediate distributional changes in animal-dispersed plants. We investigated the hypothesis that land use drives the selection of movement paths and cache sites by blue jays (Cyanocitta cristata) in the Central Hardwoods region of the eastern United States, and that these effects combine with background mast abundance and seed profitability to determine seed fates and dispersal kernels in white oak (Quercus alba), black oak (Q. velutina), and northern pin oak (Q. palustris). From 2007-2010, we radio tracked 835 acorns and 43 blue jays at 8 sites in Indiana and Pennsylvania, yielding data on primary and secondary acorn dispersal, initial caching probabilities, cache residence times, and overall seed survival rates, as well as detailed blue jay movement paths in each study site.
Results/Conclusions
Preliminary analyses indicate that acorn survival rates varied among species and years, and by Julian date within years. Dispersal kernels varied among species, sites, and years. Blue jay movements also varied among sites, with jays in row-crop-dominated landscapes largely avoiding agricultural land covers. Taken together, these results suggest a substantial behavior-mediated effect of landscape pattern and composition on acorn dispersal and survival.
