Once thought to be restricted to southernmore locales, Cope's gray treefrog is now known to occur pretty much over the entire range of the gray treefrogs. This is Hyla chrysoscelis.
Two genetic terms, diploid and tetraploid come into play when discussing these 2 lookalike species, the Gray treefrog, Hyla versicolor and Cope’s gray treefrog, Hyla chrysoscelis. At one time it was thought the the two could be identified by range and/or call with versicolor being the more northerly and having the more slowly trilled, more pleasing (=musical) call. These are now known to be invalid criteria. A friend has found versicolor as far south as Tallahassee, FL and others have found chrysoscelis as far north as Michigan and Massachusetts.

So, exactly how do you separate these 2 common treefrogs? Well, unless you have a genetics lab available you do so inexactly. With a lab, chromosome count can be determined. The gray treefrog is tetraploid, having twice the number of chromosomes as the diploid Cope’s gray treefrog. Without the lab you’ll have to extrapolate and hypothesize, determining the findings of previous researchers for the frogs from a given locale, then comparing whether the calls are pleasant and rather slowly trilled or harsh and rapidly pulsed (almost like a rivetgun)—and of course this latter will only work on the males—the females are silent. And I still find that gray treefrogs are the more common in the northerly climes while Cope’s gray treefrogs are more common in the south.

So you should now be able to at least guess at the identification of the treefrog you are listening to or watching. And of course the name, “gray”, is definitive, right. Nope. While they are often gray, they might actually be a pretty green through shades of gray to almost white. But in all phases they do have a white marking beneath each eye and extensive orange in the groin region.

Have fun.