2004 began with the sound of Chorus Frogs calling on January 3rd. This was in response to the unseasonably warm temperatures we had at the time. In point of fact Chorus Frogs can sing nearly every month of the year. However they save their most enthusiastic choruses for the mating congresses where they gather, sometimes, by the thousands, at the tail end of the calendar winter.
Chorus Frogs are often confused with their relatives the Spring Peepers (Pseudacris crucifer) but the calls of the two species make them easy to tell apart. (Chorus Frogs have a raspy, metallic, rising call that sounds very similar to a fingernail drawn across the short teeth of a plastic comb - except much, much louder. Spring Peepers have a more musical, rising, whistling call and in large choruses sound like sleigh bells jingling - extremely loud sleigh bells. Chorus Frogs are the earliest frog species in our area to begin calling, followed anywhere from a few days to several weeks later by the Spring Peepers. Both species are treefrogs.)
Why do these tiny critters make such a racket? First of all, potential mates are widely scattered and would never hear a softer call. If you've ever stood next to a pool with even a modest complement of singing males, another answer will spring to mind. You seem to approach through a strident wall of noise, and then the din seems to get inside your skull and rattle around in there. It's almost painful for a human being, and must certainly be unpleasant and highly confusing to any predator with sharper hearing than we have.
In some seasons these spring choruses can last up to six weeks, though three is more usual. This calling is done exclusively by the males. The calls serve two purposes: to advertise the presence of willing males and thereby lure equally willing females to them; and to notify neighboring males of their presence. Chorus Frogs, like all frogs, tend to space themselves evenly through available habitat and they use their calls to locate rivals and space themselves so their calls will work to greatest effect.
Once a male and female meet the male climbs on her back and clasps her under her armpits with his front legs in a position called amplexus. The two remain this way for anywhere from several hours to a day or more until mating is complete. The female lays masses of eggs that are attached to and float amid submerged aquatic plants. Once mating is completed the female returns to her usual haunts and the male returns to his perch on the pond's edge and calls for more females.
The eggs hatch in two to four weeks, depending on temperature, and the tadpoles feed eagerly on algae which in the time from egg-laying to hatching has covered nearly every submerged object in the pond. The tadpoles metamorphose by the first of May when the young leave their birth pond to make their way alone in the world
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Copyright © 2006 Jim Jung
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