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

we studied the trophic ecology of dendrobates auratus and oophaga pumilio in la selva biological station, costa rica. at this site, both dendrobatids are sympatric due to the introduction and naturalization of d. auratus in the last 24 years. diets of both dendrobatids were recorded by the analysed stomach flushing technique. microhabitats uses were defined as the site where each individual was captured. the influence of microhabitat on diets was evaluated by the dietary (prey proportions and volume) and microhabitat overlaps using pianka's (ojk) overlap index calculated with ecosim software. diets of both dendrobatids were principally characterized by the preference of hymenopterans (ants), acarines and collembolans, 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 the use of spatial resource. the absence of negative feeding interactions between dendrobates auratus and oophaga pumilio could be due to segregation in microhabitat use and possible by the abundance of trophic resource in the area. the great large volumes of formicids and acarines in the diet of this dendrobatids are in agreement with the hypothesis of these arthropods as a dietary source of alkaloids.