But I usually see them on leaves quite green.
I began to think they were actually Gray’s tree frogs, named for Asa Gray, the great 19th century botanist. Perhaps the little frogs kept sticking to him when he reached out to pick the fruits of his research.
Idle thought except I wish that those who named frogs were not, like the botanists, so prone to name the frogs for their color. Clearly, in the spring at least, frogs prefer to be heard and not seen, and if all frogs were named for their song then at least we would all have a head start when we get down to discussing what frogs sound like. Of course there is the spring peeper, and maybe you could give the frog namers come credit for the western chorus frog, which I have heard often but never seen, but I don’t exactly know what a “western chorus” is.
Instead of gray tree frog, how about trill tree frog. Here are their first choruses on our land this spring. Starting to pick up as the peepers wind down:
By May 18 that had the stage all to themselves, which in the video below appears completely black until I had the wit to raise the camcorder up to the moon.
This year as I listened to spring peepers, I fancied that each was trying to avoid catching the same beat "Peepers and Snowfleas". I think gray tree frogs try to pick up on a neighboring trill which makes for a lag which in turn gives rise to short waves of sound.
I was going to try to get to the bottom of that when we were hit with a cold spell and none of the frogs sang. When they started singing again, it seemed a question of the frogs getting back in shape. When some of my trill tree frogs got going, they were joined by a lone peeper. The tree frogs almost sound conversational and the peeper like a child trying to attract attention, of another peeper.
The tree frogs keep trilling into the summer but not in great bunches so I'll have to wait until next summer to better figure out their techniques and style.
Back to naming frogs for their singing. Actually the toads in our area, I believe they are called American toads, sing the best chorus in terms of human music making. If we had to do Beethoven's 9th Symphony, his "Choral Symphony", and we had to use an animal chorus, I would use toads in the spring. Hear what I mean:
There were a few leopard frogs there too adding some bass. Leslie and I make a pilgrimage to a bay off Quarry Point of Picton Island every May to hear the toads. Sweet music and conveniently sung in the middle of the day so we usually make a lunch of it. So I give you the "Beethoven toad."