Trophic and microhabitat niche overlap in two sympatric dendrobatids from La Selva, Costa Rica

We studied the trophic ecology of  Dendrobates auratus and  Oophagapumilio in La Selva Biological Station, Costa Rica. At this site, both dendrobatids are sympatricdue to the introduction and naturalization of  D. auratus in the last 24 years. Diets of bothdendrobatids were recorded by the analysed stomach flushing technique. Microhabitats useswere defined as the site where each individual was captured. The influence of microhabitat ondiets was evaluated by the dietary (prey proportions and volume) and microhabitat overlapsusing Pianka’s (Ojk) overlap index calculated with EcoSim software. Diets of both dendrobatidswere principally characterized by the preference of hymenopterans (ants), acarines andcollembolans, resulted in a high overlapping in prey proportions and prey volume. However,diets overlaps were not significant, suggesting the absence of negative feeding interactions.Microhabitat use was low overlapped and also not significant, suggesting a differentiation on theuse of spatial resource. The absence of negative feeding interactions between  Dendrobatesauratus and  Oophaga pumilio could be due to segregation in microhabitat use and possible bythe abundance of trophic resource in the area. The great large volumes of formicids andacarines in the diet of this dendrobatids are in agreement with the hypothesis of thesearthropods as a dietary source of alkaloids.