One of my favorite things to hear is the first sounding of the Spring Peeper chorus in March.Their chirping calls mark Spring’s beginning, even when there’s still ice melting. Our sub-species here in Maryland is the Northern Peeper or Pseudacris crucifer.
Easier to hear than find, these tiny nocturnal frogs are less than an inch long and can be variants of tan, brown, olive green or gray with a dark cross on their back. The peeping sound is made only by the males as they expand and contract their balloon-like vocal sac. As you may guess, it’s for attracting the ladies and warning off the competition. They often congregate in the damp vegetation around small ephemeral or semipermanent wetlands in groups of several hundred. Up close the sound can be deafening as each male frog chirps once per second. Their trills can be heard up to 2 1/2 miles away.
They breed close to the water sources between March and June laying up to 1000 eggs hidden in vegetation at water base. The tadpoles eat algae and tiny water life while adult Spring Peepers are insectivores, mostly on the ground level, although they can climb with toe pads.
I often felt bad for these little guys with our typical unsettled weather and wondered how they handled the return of the freezing cold and snow we often get. Apparently they produce a glucose like substance and freeze themselves to hibernation under loose bark or logs. After re-emergence, they can continue to tolerate the refreezing of part of its body fluids.
The Peepers aren’t considered to be among the endangered amphibians in our state since they can make use of even small bodies of ephemeral waters during the spring breeding season.
Here is the collective Peeper sound we hear when the temperatures are above freezing, typically by dusk through early morning: