Abstract

The amphibian response to climate change has been generally described as phenological shifts toward earlier breeding periods, with animals exhibiting smaller body sizes and male frogs producing breeding calls higher in pitch and shorter in duration. However, with >8000 species of amphibians now described, and the effects of climate change intensifying, the amphibian response to variable climates is likely to be broader and more nuanced than scientists have so far observed. For example, our previous work described a dramatic acceleration in the breeding season from spring to the previous fall, associated with warming, in Southern Leopard Frogs (Lithobates sphenocephalus); a correlation between precipitation levels and body mass indices in Crawfish Frogs (Lithobates areolatus); and the expression of a variety of daily activity patterns dependent on seasonal variations in temperature and humidity in Crawfish Frogs. Here, we add to this literature by documenting a shift in wetland breeding habitats from seasonal/semipermanent wetlands to permanent wetlands in response to decadal-long hydrologic cycles by Northern Leopard Frogs (Lithobates pipiens) and Eastern Tiger Salamanders (Ambystoma tigrinum). Three implications follow from this result. First, when challenged by climate variability, conserving amphibian diversity requires preserving wetland diversity. Second, amphibian occupancy of any particular wetland basin shifts over time, complicating conclusions drawn from short-term survey data. Third, the wetland shifts we report in response to natural climate variability might provide amphibians the flexibility to successfully respond to future climate challenges. Our insights herein derive from field studies, and we worry that the well-documented trend toward de-emphasizing fieldwork will limit scientists' ability to accurately assess threats to species from climate challenges. As the legendary writer Jim Harrison retorted when asked why he had never accepted any of the comfortable academic jobs he had been offered, “Somebody's got to stay outside.”

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