It's Easy Bein' Green... If You're a Treefrog

It seems that cold weather has finally arrived in northeast-central Mississippi.  In some ways, I find this a welcome change, but I can’t deny that it is also a bit of a jolt to go from mid-70s, temperature-wise, to 40s and below.  Of course, since this is the southeastern U.S., it goes without saying that the temperature will continue to fluctuate wildly through the rest of fall and into the winter!  On some warm days in winter, it isn’t unusual to see butterflies flitting about on the roadsides and to hear frogs calling in the soggy fields and ditches.  

I suspect that I will not be seeing frogs and toads around here for a while, though—at least, not until the next warm spell.  A day or so ago, we did get high temperatures and torrential rains, which temporarily spurred toads (Fowler’s toads, mainly) into action.  I saw several of these toads hopping over wet roads and sidewalks, traveling from one moist habitat to another, and I imagine that the rains brought a few treefrogs out of hiding, too.

In honor of Halloween, I wanted to highlight one of the most interesting features of treefrogs: their ability to disguise themselves.

Treefrogs can change hues by altering pigment distribution in the layers of cells in their skin.  This is especially noticeable in squirrel treefrogs, which can appear bright green, drab brown, dark gray, and all shades in between.  If someone in the southeast is having trouble identifying a treefrog, chances are pretty good that it’s a squirrel treefrog, since it may not perfectly match any of the pictures found in the standard field guides. 

And while green treefrogs, the larger relatives of the squirrel treefrogs, don’t have quite such dramatic chameleonic abilities, their skills are nonetheless impressive.

I took several pictures of treefrogs earlier in the month, before the major temperature downswings occurred.  In the following photo, a green treefrog is clinging to a pane of glass just below the one that the smaller squirrel treefrog is using.

Frogs on the windows

The squirrel treefrog here shows light green coloration, which is common.  These frogs are nearly always considerably smaller than green treefrogs and lack any obvious white or pale yellow stripes.

Squirrel treefrog

The green treefrog, on the other hand, usually does have white stripes running along its sides.  As befits its name, it also tends to be a very vivid green color.

Green treefrog from below...

...And from above

However, under certain conditions (heat, stress, or a need for concealment, for instance), it might turn almost black.  The frog in the photo below was resting under an umbrella at Sam D. Hamilton Noxubee National Wildlife Refuge, back in July.  It’s almost the same shade as the umbrella poles, but the white/cream stripe stands out and gives away the disguise.

Extremely dark treefrog!

As I mentioned, the toads and frogs around here have probably gone into hibernation by now—another impressive kind of concealment, in a way.  They will be alive and well, but completely hidden from view in mud, under bark, in cracks and crevices, and in numerous other places.  Some species, such as leopard frogs and chorus frogs, will breed during warm spells in the winter, but others, such as the treefrogs, will wait until early spring to emerge again.