Thank you for your comments. I thought briefly about darkening the background, but decided to leave as it was as it may still give someone the feel that this guy was actually shot outdoors (which it was) and not in a studio set up somewhere. But I will take your suggestion and try playing with it to see how it comes out. Regarding the "critter", its a type of very small tree frog. Its common name is actually "Spring Peeper" as dozens of males will form a loud chorus of "peeps" during their mating period in the early spring of the year. For many of us living in the eastern U.S., the call of this frog is the first true sign of the return of spring.
I like this photo. I like the simple but effective composition and the little guy peeping. As for *, I'd clone the greenish area in the lower left side of the picture so all the background is black. The picture *may* also benefit from some sherpening. What's the critter, btw? A gecko?