After the thrill of the woodcock flight, it’s time for the trill of chorus frogs. Walking along Boathouse road, lit up by the perigee moon, I hear plenty of individual frogs in the wet areas that dot the western edge of South Patrol Road Prairie. The mating call of a western chorus frog – typically the first one heard in our region – sounds like running a fingernail across the teeth of a plastic comb. A big sound for a frog that measures barely an inch and a half in length.
A bunch of chorus frogs calling together sounds almost like sleigh bells with a living pulse. And that’s exactly what I hear at the far northwest corner of the prairie, where lies a good-sized ephemeral pond – a pond that holds water during the spring but typically dries up over the summer. Ephemeral ponds are havens for the smaller frogs because they don’t harbor any fish, which feast on their eggs.
Following the established frog monitoring protocols, I record the air temperature – 46 degrees. I take the water temperature – 46 degrees. I look up and then record the sky code – #1, meaning partly clouded. I estimate the wind speed according to the Beaufort Scale – #1, meaning a light breeze (1 to 3 mph) in which rising smoke would drift a bit. And then I record the ambient noise level – #1, meaning I can hear a faint din of traffic from Interstate 55 about a mile away. Finally, I check my watch – 8:03. For the next 10 minutes, I listen and then record the level of frog calling – #1 would mean no calls, #2 would mean distinct individuals, #3 would mean distinct individuals overlapping. I record #4 – an indistinguishable number of frogs overlapping.
On to my second monitoring location. The enormous full moon casts sharp shadows along the path through Prairie Creek Woods, leading me to Buttonbush Pond. A dammed up former oxbow lake, the pond is home to lots of fish. And therefore few frogs. At least not the smaller ones. But the absence of frogs is important data, too. Perhaps there will be some bullfrogs and green frogs later in the season, but tonight all is silence.
It’s just me and the moonlight reflecting on a perfectly still lake save for the wake of a late-working muskrat.