Changes in frog and toad populations over 30 years in New York State

Lack of historical data against which to measure population trends greatly hampers understanding the status of amphibians. In 2001-2002 we resurveyed a hitherto unexamined baseline of monitoring data established in 1973-1980 at some 300 sites in western, central, and northern New York State, USA, and contrasted population transitions with environmental conditions to identify correlates of population change in American toads (Bufo americanus), northern spring peepers (Pseudacris crucifer), western chorus frogs (Pseudacris triseriata), leopard frogs (Rana pipiens), and wood frogs (Rana sylvatica). At the regional level, loss of habitats along roadsides has been substantial (minimally 7-12% of sites), yet within remaining wetlands, populations of most anurans have not declined. At the local level, population disappearance was associated with elevated levels of acid deposition (in American toad, spring peeper, western chorus frog, and leopard frog), urban development (American toad and spring peeper), increased forest cover (western chorus frog), and high-intensity agriculture (spring peeper); whereas population persistence was associated with increased deciduous forest cover (American toad, spring peeper, and wood frog) and low-intensity agriculture (American toad and western chorus frog). Habitat configurations at surprisingly large spatial scales (5-10 km from surveyed populations) were most closely associated with transitions in local anuran populations, implying that large-scale extinction-recolonization dynamics influence population transitions, a result land managers should consider in conservation planning.