Calling Phenology in Rana sylvatica (Wood Frog) at High-Elevation Ponds in the White Mountains, New Hampshire

Abstract

Permanent, fishless, alpine and subalpine ponds are extremely rare in New England, and amphibians occupying these ponds are unique bioindicators of environmental change because they are subject to different ecological pressures compared with lowland populations. Further, alpine and montane ecosystems are expected to undergo rapid change in the coming decades. Therefore, uncoupling the interacting effects of temperature, precipitation, and ice-out on breeding efforts may identify specific ecological mechanisms driving reproduction of amphibians. The reproductive phenology of amphibians in climatically extreme alpine environments in the eastern United States is historically under-reported and remains poorly understood. To evaluate the reproductive phenology of amphibians near the upper extreme of their vertical distribution in the White Mountains, NH, we digitally recorded amphibian calls between 2010 and 2020 at 3 permanent, fishless ponds: Hermit Lake (1180 m), Eagle Lake (1278 m), and Lakes of the Clouds (1546 m). Our study revealed dynamic changes in species assemblages and provides the first report of Hyla versicolor (Gray Tree Frog) in a subalpine context (at Hermit Lake). We analyzed the calling phenology of the earliest breeding North American anuran, Rana sylvatica (Wood Frog), and found differences in calling phenology among the 3 ponds and temporary changes in calling phenology correlated with interpolated daily weather parameters. We stress the need for further research to understand both short- and long-term, weather-driven reproductive dynamics in amphibian phenology in high mountains and their corresponding demographic effects.