Competition and predation are two of the most important factors structuring communities, and these interactions may be exaggerated when two closely related species share similar resource requirements. We studied size-based habitat selection of artificial phytotelmata for deposition of tadpoles in two species of poison-dart frogs, Dendrobates auratus and Oophaga granulifera, in Costa Rica. Dendrobates auratus exhibits male parental care, and its tadpoles are predaceous, whereas O. granulifera exhibits biparental care, and its tadpoles are obligatory trophic egg eaters. These behavioral traits are integral factors in habitat selection for these two species. We found that the predaceous D. auratus selected large- and medium-sized pools, whereas O. granulifera selected all pool sizes but had a preference for small pools. Oophaga granulifera paid a high cost for exploiting large pools experiencing 100% mortality when sharing a pool with D. auratus. The use of small versus large pools in these species is rooted in each species' divergent parental care strategies and tadpole feeding behaviors.