The Annual Chorus of Spring Peepers

The peeps are coming. No, I don't mean those sugar-covered marshmallow Easter treats, although those will be here before you know it, too. I'm referring to one of the first seasonal signs of awakening wildlife: the spring peeper. Surely, you've heard their iconic call of "peep, peep" as you pass wetland areas during the post-winter months. Spring peepers (Pseudacris crucifer) are delicate-sized tree frogs that grow to a length of a mere one or one-and-a-half inches in adulthood with a weight of only 0.11 to 0.18 ounces. The adult males tend to be smaller than the females and they are known for having white bellies and the distinctive "x" mark on their backs that decorates their shades of tan, brown or gray coloring that resembles tree bark. They have large toe pads that enable them to climb trees, although they spend most of their time on the ground. They survive the winter by burying themselves beneath logs or under loose tree bark near heavily vegetated swamps or marshes and are among the first amphibians to emerge from hibernation. Peepers are able to withstand freezing temperatures thanks to a natural antifreeze in their blood. As their body temperature gradually drops, sugars begin to concentrate inside cells; likewise, the cells will expel much of their water to decrease the amount of ice that forms, confining it to small areas that won't damage internal organs. However, hibernating peepers will still freeze and die at temperatures below about 21 degrees Fahrenheit, and they rely on the insulation of snow cover, as well as autumn leaf litter and debris to keep them alive. The peep call is made by a process of filling their vocal sacs with air that inflates a throat pouch, like a balloon. The release of the air is what lets out the peep sound, and it can either be heard as a short whistle or as a series of ascending peeps. The peep sound is a male mating call, and it can start as early as mid-March here in the Northeast, depending on the weather. As they emerge from slumber, males will congregate together and are known to sing in trios. Although the deepest voiced frog will start the call, they know that they have higher chances of attracting a female if they sing fast and loud. They mate in water, with the breeding males distinguishable by their black throats and swollen thumbs. Females lay between 750 to 1,200 eggs that attach to underwater vegetation. The males then fertilize the eggs, which can hatch in anywhere from two days to two weeks, depending on temperature. The tadpoles that hatch from the eggs have gills to breathe and tails to swim but will metamorphose within two to three months. They feed on algae and microorganisms but often fall prey to aquatic invertebrates and salamander larvae. If they manage to survive into adulthood, peepers are nocturnal predators that eat small invertebrates, like beetles, ants, flies and spiders. Their lifespan is relatively short, at only three to four years. Spring peepers are common and widespread from southeastern Canada to the eastern United States, all the way to the northern parts of Florida, as well as west to Minnesota and eastern parts of Texas. Because they dwell in moist, wooded areas and near ponds and wetlands, they are threatened primarily by a loss of wetland habitats, and although this has caused their populations to decrease in some areas, they remain at a healthy level here in New Hampshire and Vermont. The chorus of their peeps will be heard ringing through the springtime air soon enough.