How do frugivores track resources? Insights from spatial analyses of bird foraging in a tropical forest.

摘要: Frugivores often track ripe fruit abundance closely across local areas despite the ephemeral and typically patchy distributions of this resource. We use spatial auto- cross-correlation analyses to quantify patterns avian frugivory a 4-month period within forested 4.05-ha study grid in Puerto Rico. Analyses focused on two tanager species, Spindalis portoricensis Nesospingus speculiferus, their principal food plants. Three broad questions are addressed: (1) at what scales is patchy; (2) do frugivores respond abundance; (3) extent overlap between bird species? Fruit patch size, species composition, heterogeneity was variable among months, locations remaining relatively consistent months. Positive correlations suggested tanagers successfully tracked abundance. Frugivory was, however, more localized than Scales monthly variation foraging that interspecific facilitation may have been important determining locations. In particular, S. portoricensis, specialist frugivore, relied loud calls gregarious generalist, N. find new areas. Such mechanism could help explain formation mixed feeding flocks highlights potential importance share resources.