Changes in Distribution and Abundance of Anuran Species of Staten Island, NY, Over the Last Century

The global decline of amphibian species is a pressing problem that has garnered much scientific attention. Annual fluctuations of amphibian populations are a common occurrence due to weather variability, reproductive failure, or other factors. Therefore, a long-term perspective through the use of historical datasets is needed to identify persistent trends. To examine the changes in the populations of Anuran (frog and toad) species in Staten Island, NY, we used the detailed notes contained in the field journals of naturalist William T. Davis (1862–1945) to form a basis of comparison to modern surveys (2010–2011). We found very substantial changes, mainly declines, in the amphibian biota of Staten Island. Of the 10 original species, 4 have apparently been extirpated and another 4 have declined in probability of occurrence (PO), most notably Anaxyrus fowleri (Fowler's Toad), whose PO decreased 1 order of magnitude. Only Lithobates clamitans (Green Frog) and Lithobates catesbeianus (Bullfrog) have increased through time. We show that these changes are related to environmental perturbations that have occurred over the same time period.