Amphibian migration seasonally early in the eastern United States

I’ve been noticing amphibian movement postings here in Northeast (US), and have seen a few myself. As a long-time observer of this amazing phenomenon, it seems that the timing is earlier than the late-March /April of previous years. Our temperatures fluctuated but tended towards warmer than average this year.

I’d just like to open this up for discussion. What are other folks experiences, past & present? Are some species more affected than others? Are urban (UHIs) more affected? Do other factors (e.g., altitude) seem to be a factor? AND, are the migrations in sync with wetlands thawing? Feel free to add . . .

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There is a really well-documented phenomenon of amphibian calls starting earlier and earlier over time, including some in your neck of the woods (see references below). Interestingly, one of the best records we have came from an early version of community-science. The Marsham phenological record is a record of all sorts of biologically-relevant timing events recorded by five generations of the same family on their estate in the U.K. Here’s a screenshot of Table 1 from Sparks and Carey (1995). At the very bottom they list frog and toad first croak as days since Jan. 1 (so on average in late March…d 85).

Observations like you’re talking about are extremely valuable…and extremely rare. So keep up the good observing. I wouldn’t worry too much what factors may affect the kinds of observations you’re making and focus more on making regular visits to the same sites over and over, especially if there is a dataset already available to build on. However, yes, cities tend to be warmer, higher elevations tend to be cooler, and the cues amphibians use are well timed to the thawing. My rule of thumb is amphibians start to emerge on the first big rain after the last snow of the year…whenever that occurs locally. Here in Wisconsin it hasn’t happened yet, but we’re expecting rain tonight, so I’ll be out in the wetland listening and looking. Hopefully, other community-scientists around the world will be too.

Beebee, T. J. C. 1995. Amphibian breeding and climate. Nature 374:219-220.

Beebee, T. J. C., A. R. Blaustein, T. L. Root, J. M. Kiesecker, L. K. Belden, D. H. Olson, and D. M. Green. 2002. Amphibian phenology and climate change. Conservation Biology 16:1454-1455.

Gibbs, J. P., and A. R. Breisch. 2001. Climate warming and calling phenology of frogs near Ithaca, New York, 1900-1999. Conservation Biology 15:1175-1178.

Green, D. M. 2017. Amphibian breeding phenology trends under climate change: predicting the past to forecast the future. Global Change Biology 23:646-656.

Scott, W. A., D. Pithart, and J. K. Adamson. 2008. Long-term United Kingdom trends in the breeding phenology of the common frog, Rana temporaria. Journal of Herpetology 42:89-96.

Sparks, T. H., and P. D. Carey. 1995. The responses of species to climate over two centuries: an analysis of the Marsham phenological record, 1736-1947. Journal of Ecology 83:321-329.


Yes, these do fluctuate year to year with local conditions certainly, but they are tracking earlier and earlier with climate change. Wood frogs and spotted salamanders are starting to go here in RI.

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Speaking of the Marsham phenological record (though not particularly in connection with amphibians), I happened across this lovely new essay, which refers also to current initiatives of citizen science, “From Snowdrop to Nightjar: Robert Marsham’s “Indications of Spring” (1789)
by Hugh Aldersey-Williams.