BRYER, P.J.*; GLANZ, W.E.: Oviposition site selection by a tropical treefrog in a temporary pool environment

Frogs that oviposit unguarded aquatic eggs display various strategies to help ensure their offspring’s survival. At one extreme, frogs can rely on camouflage or aversive taste to protect their eggs from predators, particularly fish. Alternatively, frogs can lay eggs in places where predators cannot survive, such as in temporary pools. These ephemeral environments, although typically fishless, still possess risks from the presence of predatory invertebrates and possibility of the pool drying up before the young metamorphose. To compound the difficulty faced by ovipositing pairs, pools that are free of predators may be very small and ephemeral, while other pools that are more likely to persist for the entire period of development usually contain predatory invertebrates. We tested whether a temporary-pool breeding frog (Hyla parviceps) would discriminate between these pools. Thirty-five temporary pools near Posadas Amazonas, Madre de Dios province, Peru were censused daily for egg deposition. The pools were monitored weekly for invertebrate predators (primarily odonates), tadpole competitors of the families Hylidae and Leptodactylidae, and abiotic measurements (DO, pH, temperature, surface area, and depth). When the numbers of eggs laid in predator-free pools were compared with those pools containing predators a significant positive correlation between predator abundance and number of eggs laid was found. However, the main predictor of both predator abundance and the number of eggs laid was pool permanency, as estimated from pool volume. We feel that the frogs are choosing to ignore the risk posed by aquatic invertebrate predators because the alternative, drying risk, is greater in the smaller temporary pools.