Time- and Context-Dependent Oviposition Site Selection of a Phytotelm-Breeding Frog in Relation to Habitat Characteristics and Conspecific Cues

Abstract

Time- and context-dependent nest site selection of a phytotelm-breeding frog (Kurixalus eiffingeri) was evaluated in a natural bamboo habitat in subtropical Taiwan from 2004 to 2005. At the beginning of the breeding season (mid-March), frogs preferred bamboo stumps with large water holding capacity, which may be considered high-quality stumps since water availability is critical to the survival of tadpoles. Prior to 21 May, no tadpole-occupied stumps were re-used even though they represented 10–40% of total stumps at the study site; however, tadpole-occupied stumps were consistently re-used afterwards. Stumps with fewer tadpoles were used proportionally more than those with more tadpoles. By choosing the stumps with fewer tadpoles, the negative competitive effect of the late-clutch tadpoles on the early-clutch tadpoles would be somewhat alleviated. Male frogs did not breed in the same bamboo stump for consecutive breeding events, which may relate to the male reproductive strategy. We propose that it would often be a better strategy for a male frog to breed in different stumps than to stay in the same stump, even if the stump was of high quality. Breeding in multiple stumps would increase the number of breeding opportunities by reducing the interval between successive mating attempts, minimize the inter-clutch competition between tadpoles, and avoid competition between two cohorts of its own genetically-related tadpoles. Our results suggest that stump quality is indicated by water holding capacity and the number of the tadpoles in the stump during early and late breeding seasons. Thus, oviposition site choice in this species is dependent on stump quality, but stump quality is both context- and time-dependent.