One of these is not like the other. But when it comes to Virginia’s two gray treefrogs, don’t count on being able to tell the difference. The Cope’s gray treefrog (Hyla chrysoscelis) and the common gray treefrog (Hyla versicolor) are so visually alike that only an expert—or a high-powered microscope—can discern the distinction. “If you are looking at one in the wild, there is no difference,” says Mike Clifford, chairman of the education committee for the Virginia Herpetological Society.
In fact, only recently did it become clear that the two are, well, two. Although researchers had noted as far back as the 1930s some variation in the calls between apparently identical treefrogs, says Clifford, it took laboratory analysis to determine that there were indeed two species masquerading in the same frog form.