The Call of the Spring Peeper

March 14, 2016
Spring Peepers
S.H. LeeThe male spring peeper emits a shrill call to establish his territory and to attract mates.

The spring peeper, a frog species, is named for its most distinctive feature: a high-pitched mating call that is inextricably tied to the end of winter—and that’s very loud.

“To hear hundreds and hundreds of males making that sound, if you’re camping in a tent or shelter, or if you have a pond near your house, it can be pretty intense,” says Nicky Pizzo, an AMC senior naturalist based at Pinkham Notch in New Hampshire. “People are shocked when they see the size of them, given the sound they can make.”

Call and Response
Female spring peepers average only about 1.5 inches long, and males—the individuals responsible for all that noise—are even smaller. They’re both tan, with a dark brown “X” on their backs and round toe pads, “almost like little suction cups,” which help them climb trees, Pizzo says. Spring peepers are nocturnal, hiding from predators under leaf litter and loose tree bark during the day and emerging at night to eat ants, flies, and other bugs.

As warmer weather in early spring melts bodies of water, spring peepers dig themselves out of their hibernation spots and head to open water to mate. This often happens in May in New Hampshire but may start as early as March farther south.

The males emit their shrill peeps after dusk to establish their territory and to attract females. After two spring peepers mate, the female leaves hundreds of eggs in the water and heads back into the woods. The male resumes peeping to find another partner. Males call thousands of times per night, every night, for several weeks. “They have one thing on their mind,” Pizzo says.

Not a Peep
The males’ serenade emanates from a vocal sac about the size of a quarter. As with other frogs, this sac expands and deflates like a balloon to amplify the call.

If one male spring peeper grabs another and tries to mate, the male being embraced makes a sound that differs from the mating call, as if to caution, “Hey, I’m not what you’re looking for,” Pizzo says. The males also have distinct calls for defense and for the moment before mating. Some individuals peep in the autumn, when weather conditions are similar to spring.

Spring Fever
If you hear a nighttime chorus of spring peepers, try creeping closer for a peek. They will stop calling when you are near, but if you approach the water’s edge quietly and stand still, they may start up again. Shine a light at ground level or about a foot up, and you may spot the males’ glistening vocal sacs inflating and deflating. You may also spot couples mating in the water.

If a pond-side chorus that has been calling for several nights falls silent, mating season has likely ended in that location. Instead, Pizzo recommends looking for frogs on the trail or in the forest as the males move back into the woods.

About six weeks after the mating season, in late spring or early summer, the next generation of small frogs will move into the forest, so watch for hopping action near wetlands on your hikes.


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Heather Stephenson

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