Does foraging activity change with ontogeny? An assessment for six sympatric species of postmetamorphic litter anurans in central Amazonia

Abstract

We studied the foraging activities of six frog species in their natural habitat, the leaf litter of tropical rain forest in central Amazonia. To describe intraspecific ontogenetic change in general activity during foraging, we used four indices of general activity (movement frequency, velocity when moving, time spent moving, and total distance moved). The association between each of the four indices and the size of frogs varied among species. The indices of foraging activity do not represent independent information. Therefore, we reduced the dimensionality using a single ordination obtained by multidimensional scaling, and investigated its relationship to frog size and type and size of prey. There was a significant relationship between the combined index of foraging activity and frog size in three of the six species. Foraging activity predicted the intraspecific change in the type and size of prey for Eleutherodactylus fenestratus, partially for Adenomera andreae, Epipedobates femoralis, and Dendrophryniscus minutus, and not for Bufo cf. typhonius and Colostethus marchesianus.