Trophic ecology of juvenile amphibians: relative level of myrmecophagy in two anuran species

Research on trophic niche dimensions is essential to understanding the role of species in ecosystems. In the case of amphibian conservation, it is particularly important to study juveniles, given the vulnerability of this life stage. Here, the diets consumed by juvenile Rhinella arenarum and Odontophrynus sp. were evaluated, with special attention paid to the incidence of ants. Diet composition was quantified by analyzing the amphibians' stomach contents. The representation of different taxonomic prey groups was determined, and the relationships between the amphibians' morphological traits and the characteristics of their prey were explored. Diet composition and diversity differed between juveniles of the two species. Juvenile R. arenarum occupied an intermediate position along the specialist-generalist spectrum. Their most commonly consumed prey were ants (mainly Solenopsis and Linepithema) followed by mites. Juvenile Odontophrynus sp. had a more generalist diet. Their most commonly consumed prey were Isopoda followed by Coleoptera and miscellaneous larvae. Snout-vent length (SVL) was greater for juvenile Odontophrynus sp. than for juvenile R. arenarum, but the latter consumed more prey. The results suggest that juveniles of R. arenarum tend to specialize more on ants than do juveniles of Odontophrynus sp.