A Spring Chorus — glwalker.com

Western chorus frogs, Pseudacris triseriata, singing their song (sorry for the shaky video, hand-holding 500mm is tricky)

Every year around this time, I become mildly obsessed. It doesn’t last long, but in late February through early March I find myself spending hours listening to the droning chorus of hundreds of frogs, staring intently into their shallow ponds, and yet seeing none. It is maddening. Their annual song is one of my favorite sounds in nature. It foretells the coming spring, the brighter, warmer, longer days ahead, and yet it inevitably triggers a burning obsession that I apparently cannot contain. Once I start looking I feel compelled to spot one. How can something SO loud, SO abundant, and SO close remain effectively invisible? Finding one cannot be that hard…. but it is.

It is the western chorus frog, Pseudacris triseriata, also known as the striped chorus frog, that is the object of my obsession. These noisy amphibians often get lumped collectively into the spring peeper bucket, but while both are a type of chorus frog, the spring peeper is a separate species called Pseudacris crucifer. Spring peepers make a very different sound. They peep (crazy, right?), whereas western chorus frogs make a repeated, cicada-like croak. We have both in this area, and occasionally I can make out the peep-peep-peep of a lone P. crucifer, but it is all but drowned out by the cacophony of the far more abundant triseriata.

Many times in past years I have been shut out, staring into the swamp endlessly, surrounded by frogs, but never seeing a one. This year (so far) I have fared a little better. My chorus frog game is improving! After a solid hour sitting dead still and scanning the flotsam for gleaming golden eyeballs, I finally found one. And once I found one, it was as if my eyes had been calibrated. I started seeing them everywhere, counting a least a few dozen out of hundreds or perhaps thousands. Such sweet relief, an obsession satisfied…. until next year.

A few frog-finding tips, if you find yourself overcome with an inexplicable need to find the source of this annual chorus — “the very voice of the weather,” as Thoreau called it:

The frogs will, of course, stop calling when you come near. But sit quietly for a few minutes and you will hear a tentative croak or two close by. Once the frogs notice that nothing bad happened as a result, they will begin singing in full force again. Assuming you don’t move or make too much noise, they will ignore you. They have confidence in their camouflage, and that confidence is justified.
They are typically half-in / half-out of the water, perched on partially submerged sticks and leaf litter. Look for little frog heads and shining frog eyes.
Look for the movement of their inflating vocal sacs as they call, but don’t scan too quickly. The pace of their calls and corresponding movement is relatively slow, and if you move on too quickly you will miss the motion.
Most importantly, realize that they are VERY loud, over 100 decibels (like a smoke alarm!). Their sound is generated in their little frog larynx, not unlike our vocal cords. That big balloon of a vocal sac is a resonator, amplifying their calls. Because they are so unexpectedly loud, they are typically farther away than you expect. The individual frog that startles you when it resumes croaking is not as close as you think. It might sound three feet away, but it is probably more like thirty. My photos are with a 500mm lens and they are heavily cropped. The closest image was perhaps fifteen feet away, and the frogs are only about an inch and a half long. You have to look in the right spot with a keen eye. Binoculars help.

If you want to see and hear these little frogs for yourself, good luck! Just beware, you might find that you can’t leave until you find one. But then again, there are worse ways to spend one’s time.

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