Context-dependent reproductive site choice in a Neotropical frog

Abstract

In organisms whose offspring develop in discrete habitat patches such as pools, studies have frequently shown that adults avoid sites based on a single risk factor facing offspring. However, natural reproductive sites often vary in multiple risk factors in both space and time. In this study, I used choice tests among field mesocosms to determine whether adults of a Neotropical anuran, Edalorhina perezi, select the safest pools for offspring based on two biotic risks of different magnitude: insect predators and conspecific competitors. I also investigated whether adult site-choice was context dependent (i.e., whether it varied by sex or by season or whether it was based on local pool quality). I found that both sexes avoided pools containing predatory insects, but only females significantly avoided those containing conspecific tadpoles. When offered two risky options, both sexes favored pools with competitors over those with predators. Site-choice behavior also varied depending on the temporal and spatial context. Female sensitivity to insect predators decreased late in the season. In addition, both sexes exhibited dampened reproductive activity when only risky sites were available locally. This study emphasizes that social and environmental factors simultaneously impact reproductive site choice. Whether a site is accepted ultimately depends not only on the assessment of mortality risks to offspring but also on the sex and spatiotemporal context of the decision maker. Key words: amphibians, calling sites, choice experiments, Edalorhina perezi, insect predators, oviposition sites, Peru, pool mesocosms, reproductive site choice, tadpole competitors, tadpole mortality risk. [Behav Ecol 14:626–633 (2003)]