It wasn’t the bottom of the 9th, but more like the top of the 5th when I finally quit the Tiger Baseball playoff game for the night. It was getting late and they were playing the A’s in Oakland and, well…it was late and “we” were winning , so please don’t get on me about being a true fan. Hey, did I say it was late? Well it was. At any rate, I turned off the television and wheeled around to turn off the light when I saw someone looking at me through the sliding glass door. His face and the better part of his body, was pressed up against the glass. And, I should mention, he was completely naked.
If the sight had been that of a human Peeper (as in a Tom), the sight would have elicited a cascade of inner Psycho music and an immediate bowel-emptying incident. But, the Peeper in this scenario was a frog – not a Peeper (as in Spring) but a Tree Frog (as in Gray). I must admit that I jumped a tiny bit before fascination took over and I ran for my camera. Sure, late night frogs trump late night Tigers in this man’s world. It wasn’t really that late.
Technically there are two kinds of Tree Frogs in our region and both go by the name of Gray Tree Frog. Both climb trees, have pebbled skin, and trill like miniature raccoons. The Cope’s Gray Tree Frog is nearly identical in appearance to the standard Gray Gray Tree Frog except that it has a nasal quality to its voice along with a few more slight, but biologically significant, differences. My peeper was of the usual Gray Gray Tree Frog type.
Grays can alter their skin color from gray to green depending on their daytime camouflage needs (thus the scientific name Hyla versicolor). In spite of the name, the mottled green mode can be considered the default coloration since night hunting doesn’t require any camo. The belly view presented a display of the bright yellow inner leg patches typical of the species and also revealed the sex identity. It’s all about throat shading, you see. Males have dark throats while females have light ones. This peeper wasn’t a Tom after all, it was a Tomisina.
The creature was stuck to the glass like one of those plastic goo-balls. Although there is a slight possibility that she was trying to watch the Tigers game, I am fairly confident that it was seeking the insects which were attracted to the light. Regular old American Toads frequently hop about in the dim glow of the night window for the same reason. They, however, are earth bound fellows who can only dream of doing what their arboreal Anuran cousins can do. The only way that an American Toad could hope to stick to the window glass in this manner would be as Potato Gun ammunition (or if the house suddenly accelerated forward at 60 miles per hour). Gray Tree Frogs are equipped with so-called “sucker discs” that enable them to climb trees, branches, and slick surfaces such as glass.
It is actually better to refer to these structures as toe pads because they are not suction cups in the true sense of the word. Detailed micro photography of tree frog pads shows them to be covered with thousands of hexagonal structures separated by tiny crevices (see here) Mucous glands line the bottom of each crevice. In a remarkable case of natural form repetition, basalt formations such as those found at the Giant’s Causeway in Ireland duplicate this structure in mega scale (see here). The surface of the Tree Frog columns are covered with tiny bumps, so they aren’t exactly like the Irish rock example. And, as far as I know, there are no mucous glands at the bottom of the Basalt columns but hopefully you can get beyond all that. Next time you are in Ireland you can hop across the crackled rock surface screaming “Look everyone, I’m a wee little leprechaun and am standing atop a tree frog toe pad.” Please let me know how that goes for you in the case you get such a golden opportunity.
The little Gray Tree Frog lassie was able to climb the dry glass (oddly enough, an overly wet surface decreases this effect and the frog will slide) through the action of the sticky mucous and the multiple hex cells. Pressure creates suction. Release of same enables the walker to lift off and re-apply. Toes widely spread, each pad is allowed to make full contact for full effect.
Overall the effect is somewhat creepy when viewed by a sleepy human. I do wonder what this sleepy human looked like to the wee window frog. “Look everyone,” he might say, “I’m a wee little hopper and I’ve climbed the magic window and looked into the face of a two legged giant with three eyes.”