Checklist of Amphibians and Reptiles of Barro Colorado Island, Panama, with Comments on Faunal Change and Sampling. Smithsonian Contributions to Zoology, 1969 No. 10.

摘要

One hundred species of amphibians (32) and reptiles (68) are estimated to occur on Barro Colorado Island, on the basis of approximately 47 years of collecting. The island is a seasonally wet, tropical forest locality in man-made Gatun Lake, central Panama. The faunal composition has not been static since the island's formation in 1912-1914. Some species have disappeared from the island whereas some others seem to be recent arrivals. Faunal change is at least partly correlated with vegetational succession, as old clearings change toward mature forest. The extirpation of certain 'edge' species and their failure to have recolonized the laboratory clearing indicates that it is easier for a resident population to become extinct than for new colonization to occur. The sampling of such a complex, tropical herpetofauna is shown to be not so difficult as might be expected. Man-hours of collecting are plotted against percent of the herpetofauna for several collections, indicating that nearly one-half of the species can be collected in a few weeks of intensive effort in the rainy season. Approximately 80 percent of the species recorded from the island had been collected by 1931, after only about a decade of sporadic, unsystematic collecting by various persons. The generalization that tropical species have lower population densities than temperate species may not be valid for such groups as frogs and lizards but does seem true of snake faunas in low, humid forest regions. Snakes also are more difficult to collect in the tropics because of shifts in habits. There is a great expansion of tropical snakes into arboreal situations and a general avoidance (by all vertebrates) of rock and log microhabitats, which are frequently occupied by large arachnids. Small terrestrial snakes of lowland tropical forests tend either to be fossorial or to inhabit the leaf litter, where they are difficult to detect. Seasonal aggregations of snakes are rare in the wet tropics.