Saturday, March 28, 2009

Spring Peepers

First frog program of the year last night; I was afraid it was going to be too chilly for much frog activity, but we were pleasantly surprised to find the Reflecting Pond absolutely rockin' with Spring Peepers (Pseudacris crucifer) in full chorus. These tiny little frogs are no bigger than your thumb, and can be identified by the vaguely cross-like marking on their backs, which is where the scientific name "crucifer" comes from. They may be tiny, but these little frogs pack some mighty vocal power. A few minutes spent in the middle of an army of chorus frogs and your ears actually ring. ("Army" is the term for a group of frogs, like "flock" is to birds). Only the males call, trying to attract a female. Calling is the most energy expensive activity a frog can do, so the females know that males able to call long and loud are likely to be healthy and good potential fathers for their eggs, genetically speaking, anyway. Once the eggs are laid, both male and female Spring Peepers head back to the forest, and the tadpoles grow up with no parental care needed.
Here's a video clip of a male Spring Peeper calling, with another nearby, probably a female. The male really puts his whole body into the effort of calling - hopefully the female peeper was impressed!

And another short clip of a peeper calling - this one looked like he waved at me!

Peepers were the only frog we heard calling, but I did spot one very sleepy Bullfrog (Rana catesbeiana) poking her head up. Spring Peepers spend the winter in the forest, burrowed underground. They actually have an anti-freeze-like substance in their bodies that prevents them from suffering damage from sub-freezing temperatures. Bullfrogs, on the other hand, spend the winter under the ice of the pond, hibernating in the leaves and muck at the bottom. Because of the cold temperatures their energy needs are very low, and they can take in enough oxygen through their skin to sustain them.

I could tell this Bullfrog was a girl because her tympanum, or ear, the little circle just beneath her eye, is smaller than the eye. On a male Bullfrog the tympanum is larger than the eye. This doesn't work for Spring Peepers, but you can still tell the males apart by the yellowish or dark brown deflated vocal sac on their throats, while females have white throats.

1 comment:

mfb said...

Very neat videos. I am always impressed with how bold the peepers are; they keep on calling even when in the middle of a flashlight beam.