Christopher W. Harbison, Julia L. Michalak, Jonathan W. Moore, Maurine B. Neiman, and Carey N. Sydney
Department of Biology, Carleton College, Northfield, MN, 55057
Abstract. We assessed the habitat preferences of the poison dart frog Dendrobates pumilio by determining frog abundance and distribution across habitat type (primary versus abandoned plantation forest) and soil type (alluvial versus residual). We also surveyed the distribution and abundance of two different plants (Dieffenbachia spp. and fallen bromeliads) that are utilized as tadpole deposition sites by D. pumilio and recorded the presence or absence of tadpoles in the axils of these plants. D. pumilio and Dieffenbachia were both found to be significantly more abundant in abandoned plantation habitat than in primary forest, and D. pumilio and Dieffenbachia abundance were strongly correlated within plantation plots. There were more tadpoles found in Dieffenbachia than in bromeliads. A survey of sex and juvenile ratios found that females and young juveniles were significantly correlated to Dieffenbachia abundance. There was a strong but non-significant correlation of adult male frog abundance to Dieffenbachia abundance, perhaps due to the spacing constraints of territoriality. No correlation was found between older juveniles and Dieffenbachia abundance, a finding that may be related to territorial interactions with adult males. We believe that Dieffenbachia is driving the preference of D. pumilio for plantation forest. Our data also indicate that Dieffenbachia is a more important reproductive resource for D. pumilio than fallen bromeliads.