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Spring Peeper – Pseudacris crucifer

General: Spring Peepers (Pseudacris crucifer) are known for their songs that are often considered a melodic announcement of spring. Although these chorus frogs are known for their sounds, these tiny amphibians are rarely scene due in part to their camouflaged pigmentation and nocturnal habits.

Description: Spring Peepers are a diminutive amphibian, measuring a mere ¾” to 1½” in length and 3g to 5g in weight when fully grown. In addition to their petite size, their coloration aids in providing camouflage, making them elusive and hard to spot. Males and females are similar in appearance. Spring Peepers are generally tan, brown, olive or grey, accented with dark lines across their backs that form “X” patterns and dark bands around their legs and between their eyes. They may sometimes have a reddish or orange pigmentation. Spring Peepers have cream or white undersides and throats, although males display gray throats during the mating season. Spring Peepers are capable of a degree of color-change and can lighten or darken their pigmentation based on their surroundings. They have moderate webbing on their feet and large, round, sticky toe pads that aid in climbing1, although they rarely climb higher than 3’ off the ground. Spring Peepers can be identified by the large ‘vocal sacks’ located under their chins. In order to produce their signature songs, Spring Peepers inflate these sacs with air to a size equal to their entire bodies2.

Subspecies of the Spring Peeper may be identified by unique coloration. Northern Spring Peepers tend to have unmarked bellies while Southern Spring Peepers have spotted bellies3.

Spring Peepers are best known for their high-pitched songs, harkening the start of spring in northern habitats as males begin performing mating displays in March. However, southern Spring Peepers begin their mating songs as early as November, causing the name Spring Peeper to be quite ironic for these populations. Their monosyllabic whistle is often mistaken for the chirp of crickets as it is repeated at a rate of 20 times a minute, although crickets are only heard in the late summer and fall. Spring Peepers may be heard on rainy or cloudy days but are most frequently active on warm, damp nights. By late summer their calls have usually fallen silent but they can be heard again ringing from forests during the fall. Spring Peepers sometimes slur together two syllables and produce a trill-like sound. Males sing in trios and the males with the deepest calls typically lead the choruses. Groups of singing Spring Peepers are often described as sounding like sleigh bells.

Spring Peepers hibernate during the winter in spaces beneath tree bark or under logs, allowing their bodies to almost entirely freeze. In order to survive, Spring Peepers produce and store high levels of glucose in their cells that prevents cells from freezing and rupturing, preserving the frog until the spring thaw.

While their lifespan in the wild is still unknown, Spring Peepers live, on average, 3 to 4 years in captivity4.

Habitat: Spring Peepers live in close proximity to water sources such as ponds, streams, marshes and temporary pools and inhabit swampy wooded areas, and grassy lowlands. They spend the majority of the year amidst debris on forest floors but mate and deposit their eggs in the water.

Within their habitats Spring Peepers are preyed on by birds, snakes, and some mammals. Aquatic insects, turtles, and fish consume their eggs and tadpoles.

Location: Populations of Spring Peepers can be found in eastern and central portions of the United States and Canada. Native populations have been found as far south as eastern Texas and northern Florida and introduced populations have been reported in Cuba.

Diet: Spring Peepers are carnivorous, consuming a diet of beetles, flies, ants, spiders, mosquitoes, gnats, aphids, termites, and crickets. Spring Peepers hunt and feed on forest floors and in low vegetation, rarely exceeding an elevation of 3’.

Reproduction: Spring Peepers breed once annually, from November to March in southern habitats and from March to June in northern areas. The breeding season begins as males emerge from hibernation and commence their mating songs during damp, warm nights. Males gather by the hundreds around water sources, singing in trios and establishing individual territories. Females choose their mates by the quality and frequency of their calls and their overall size.

Spring Peepers mate and deposit their eggs in freshwater ponds or temporary pools that lack fish, showing preference for areas deeper than those used by other species. Males play no reproductive role beyond fertilization. Females deposit the eggs with a nourishing yolk but provide no additional parental care. Females deposit up to 1000 eggs, which measure 1mm in diameter, individually or in clusters of two to three along submerged vegetation. Eggs double in size when fully hydrated and hatch within 6 to 12 days, depending on temperatures. Embryos and larvae are sensitive to water conditions and cannot survive in a pH ranging from 4.2 to 4.5. During the larval stage, tadpoles feed on algae and aquatic organisms. Spring Peepers are slightly larger in their larval stage than when fully mature. The length of the larval stage is partially dependent on water conditions and availability, but ranges from 45 to 90 days.

Spring Peepers reach sexual maturity in 2 to 3 years5.

Notes of Interest: Spring Peepers’ scientific classification, crucifer, is Latin for ‘cross-bearer,’ appropriately assigned to this tiny frog who bears an x-shaped marking on its back.

The choral song produced by groups of Spring Peepers is similar to the sound of jingle bells and has earned them the nickname Pinkletinks from residents of Martha’s Vineyard6.

1. http://animals.nationalgeographic.com/animals/amphibians/spring-peeper/
2. http://www.dnr.state.md.us/features/spring_peepers.asp
3. http://www.enature.com/fieldguides/detail.asp?recnum=AR0014
4. http://animaldiversity.ummz.umich.edu/accounts/Pseudacris_crucifer/
5. http://animaldiversity.ummz.umich.edu/accounts/Pseudacris_crucifer/
6. http://www.dnr.state.md.us/features/spring_peepers.asp