Use of large field enclosures to study the terrestrial ecology of pond-breeding amphibians

The terrestrial stage of pond-breeding amphibians has been the subject of few ecological field experiments, partly because terrestrial individuals of many species are difficult to capture, observe, and manipulate. I tested a new strategy for sampling terrestrial, fossorial, pond-breeding amphibians within large field enclosures. Ambystoma opacum and A. talpoideum were placed in 225 m(2) enclosures shortly af ter metamorphosis. Pitfall traps were placed along the enclosure walls to recapture individuals when they reached maturity and attempted to migrate to a breeding pond. Data were obtained on survival to, age at, and size at first reproduction comparable to data obtained from natural populations using terrestrial drift fences with pitfall traps located at breeding ponds. Doubling density in the enclosures by adding an equal number of either the same or the other species had no statistically significant effect on survival to first reproduction of A. opacum.