Space use of Amazonian poison frogs: Testing the reproductive resource defense hypothesis

In most Anuran species, space use includes a lek mating system with defense of a calling site for only a short time period during an individual's lifespan. In contrast, territoriality over a longer time period by one or both of the sexes has been reported in all studied dendrobatid frogs. In most dendrobatid species, territories are defended for reproductive purposes, and typically, males vocalize from these territories to attract mates and repel rivals. It has been hypothesized that reproductive resources such as oviposition sites or tadpole deposition sites are defended. For reproductive resource defense to occur, reproductive units (eggs or tadpoles) must be deposited at sites where the territorial individual displays agonistic interaction with intruding individuals. Here, we challenge this assumption in a field study on the poison frog Dendrobates ventrimaculatus in French Guiana. We show that home-range size is affected by spatial distribution of bromeliads. Clutches of eggs were found to be predominantly deposited in bromeliads located inside the 50% Kernel core areas of activity within male territories, although tadpoles were deposited more frequently outside these core areas. Vocalization of males only occurred in agonistic interactions with other males or while courting a female. Our data show that (1) males of D. ventrimaculatus defend small territories containing their reproductive resources, (2) these resources are not limited in number, and (3) territories are not defended for characteristics supporting advertisement vocalization. We conclude that males defend territories to increase the success of courting a female without interruption by other males.