Invasive species represent a significant threat to global biodiversity and a substantial economic burden. Burmese pythons, giant constricting snakes native to Asia, now are found throughout much of southern Florida, including all of Everglades National Park (ENP). Pythons have increased dramatically in both abundance and geographic range since 2000 and consume a wide variety of mammals and birds. Here we report severe apparent declines in mammal populations that coincide temporally and spatially with the proliferation of pythons in ENP. Before 2000, mammals were encountered frequently during nocturnal road surveys within ENP. In contrast, road surveys totaling 56,971 km from 2003–2011 documented a 99.3% decrease in the frequency of raccoon observations, decreases of 98.9% and 87.5% for opossum and bobcat observations, respectively, and failed to detect rabbits. Road surveys also revealed that these species are more common in areas where pythons have been discovered only recently and are most abundant outside the python's current introduced range. These findings suggest that predation by pythons has resulted in dramatic declines in mammals within ENP and that introduced apex predators, such as giant constrictors, can exert significant top-down pressure on prey populations. Severe declines in easily observed and/or common mammals, such as raccoons and bobcats, bode poorly for species of conservation concern, which often are more difficult to sample and occur at lower densities.

Recent awareness of amphibian declines has raised the need for effective monitoring programs. Call surveys are a standard approach to monitoring populations of most anuran species. Temporal variation in calling activity, however, may result in failure to detect some species. Automated recording systems (ARS) allow consistent sampling for extended periods with little or no disturbance to calling anurans. We used an ARS to measure temporal variation in anuran calling activity during the summer of 1997 at a Carolina bay on the U.S. Department of Energy's Savannah River Site, South Carolina. We documented considerable interspecific variation in calling activity, a phenomenon that, using traditional call survey techniques, would result in failure to detect some species. In particular, we found that Southern Leopard Frogs (Rana sphenocephala), thought to breed only in early spring and fall in the region, called consistently from midnight until dawn during July. Because protocols for most call surveys d...