|The Question: I found this little guy in my backyard. It’s smooth and green on top and gray/tan on the bottom. It has striped legs and horizontal pupils. What is it?
Submitted by: Elizabeth, southern Indiana, USA
|The Question: I found this little guy in my backyard. It’s smooth and green on top and gray/tan on the bottom. It has striped legs and horizontal pupils. What is it?
Submitted by: Elizabeth, southern Indiana, USA
The Question: It’s 9:00 p.m. and I live next to a small woods. I hear a noise outside and was wondering if it was a bug or bird. I hear this noise regularly. It’s a repetitive trill same note. Here’s my recording:
Submitted by: Diane, Ohio, USA
The Short Answer: I’m combining Elizabeth’s question and Diane’s question because they are both dealing with the same species … maybe. Elizabeth’s picture is of either a gray tree frog (Hyla versicolor) or a Cope’s tree frog (Hyla chrysoscelis). They are pretty much impossible to tell apart by appearance, especially since both are so highly variable. In fact, despite the “gray” in its name, the gray tree frog can be any color from green to brown or gray, as this collage shows. And the Cope’s has the same variation. To make it even more difficult, any one individual frog can change color to some extent depending on its surroundings. What both species have in common is yellow markings on the underside of their hind legs, so look for that.
The way experts tell the two species apart is by their call. Carl Gerhardt, at the University of Missouri, who studies communication in frogs, says that above 75 degrees, the difference between the two species is that you can hear distinct pulses in the call of a gray tree frog, whereas the Cope’s sounds more like a buzz. (As the temperature drops, however, the trill of the Cope’s slows down and begins to sound more like the gray.) Listen to these two videos and you should be able to tell the difference:
Cope’s tree frog: http://www.biosci.missouri.edu/gerhardt/video/Hyla%20chrysoscelis.mov
Now listen to Diane’s recording again and try to guess which frog Diane’s is. Click here to see if your answer agrees with Dr. Gerhardt.
Another way to tell which frog you have is by location. As the range maps at these links show, if you’re looking at one of these frogs in the most southeastern states of the United States (Florida, Georgia, Mississippi, Alabama, South Carolina), you probably have a Cope’s tree frog. If you are in the northeast, from New York to New England, you almost certainly have a gray tree frog. In all the other states, it’s possible to find both. Where Diane lives in Stark County, Ohio, only the gray tree frog has been recorded, so that’s confirmation that Dr. Gerhardt’s identification from the frog’s song is correct.
Gray tree frog range map: http://www.amphibiaweb.org/cgi-bin/amphib_query?special=maps&genus=Hyla&species=versicolor
Cope’s tree frog range map: http://www.amphibiaweb.org/cgi-bin/amphib_query?special=maps&genus=Hyla&species=chrysoscelis
Elizabeth, by the way, said she took her picture in southern Indiana, which means she probably has a Cope’s tree frog.
The Weird Genetics: It’s clear that the Cope’s tree frog and the gray tree frog are very closely related. Just how closely was discovered in