Northern Spring Peeper
Pseudacris crucifer

Photo of Northern Spring Peeper on a branch - courtesy of John White

Among the first true signs of spring in Maryland is the cacophonous sound of the tiny, thumb-nail sized Chorus Frogs, known as Spring Peepers.  Along with the return of the Osprey and the departure of Canada Geese, the Spring Peeper is a strong indicator of warmer days to come.  The loud, peeping chorus of Spring Peepers means winter is finally coming to an end. These little frogs are among the very first to call and breed in the spring. The call is very important during the breeding season, as the female will choose a mate by the quality of its call.

The Spring Peeper, though nocturnal, is one of the most familiar frogs in the East. Like many of the Chorus Frogs, the Spring Peeper is often heard, but not seen. It gets its name from its call, which consists of a single clear note or peep, occurring once a second. Only the males sing, calling from shrubs and trees standing in or overhanging water.

The faster and louder a male sings, the more likely he is to attract a mate. A male peeper may also give a lower-pitched trilled whistle, usually when another male has moved too close to its calling site. During the daytime, peepers often call during light rains or in cloudy weather.

The intensity of calling increases and can become a deafening chorus during humid evenings or just after a warm spring rain when many males congregate. The resulting chorus sounds of many peepers calling together sounds a bit like jingle bells. In fact the residents of Martha's Vineyard, Massachusetts, call these creatures Pinkletinks.

Photo of Northern Spring Peeper on a branch - view of the back - courtesy of John WhiteThe Spring Peeper, like other Chorus Frogs, is a small animal attaining an adult length of only a little over an inch long. A characteristic of the Spring Peeper is the dorsal marks that form an X on the back. It usually isn't a perfect X, but some form of it. Their Latin name, Pseudacris crucifer, was chosen because  "crucifer" in Latin means “cross bearing.”

Pseudacris crucifer has moderately webbed feet and noticeable disks on its fingers and toes. Like all treefrogs, peeper toepads are sticky and round, useful for climbing trees and other plants. It also has dark bands on its legs and a dark bar between its eyes. The general coloration is a variation of brown, gray, or green. This frog has some color-changing ability and can darken or lighten, depending on its mood or the surroundings.

Because they breed in permanent or temporary fresh water, pools are a habitat requirement. This frog is found in fishless, temporary wetlands associated with forested habitat like marshy woods, non-wooded lowlands, or near ponds and swamps. Although it is a good climber, spring peepers seem to prefer to be on the ground or hiding in leaf litter.

Photo of Northern Spring Peeper egg mass shown next to the pont of a pencil  - courtesy of John White

The breeding period is from February -June, when the female lays  200 to 1,200 eggs. Peepers do not lay eggs in strands or clumps. Unlike all other MD frogs, they lay their eggs singly, attached to submerged aquatic vegetation.  After the breeding season, they move into woodlands, old fields or shrubby areas.

Depending on the temperatures, eggs may hatch within two to four days or may take up to two weeks during cooler periods. The newly hatched tadpoles become late tadpoles by early July. When they become tadpoles, they breathe with gills and swim using a tail. Peeper tadpoles are bigger than the adult peepers. As they mature, they lose their tail, and they develop lungs for breathing air. Transformation occurs within eight weeks when the young tadpoles are fully transformed into young frogs and leave the pond.

By the end of the summer, they have reached the adult size of about 1 - 1 1/2 inches. Maturity is reached within one year. As the days cool, the peepers dig into the soft mud near ponds for the winter. During the winter, peepers go into a type of partly-frozen hibernation, and they re-emerge when the weather warms.

Quick Facts:

  • Length: in. to 1 in. (record 1 in.)
  • Weight: 3 to 5 g. (0.11 to 0.18 oz.)
  • Calls: Short, loud, high-pitched peep. Many individuals singing together sound like sleigh bells.
  • Sounds like: spring peeper call (348k) - spring peeper chorus(106k)
  • Eats: The spring Peeper eats mainly small insects including ants, beetles, flies, and spiders. They catch them with their long, sticky tongue.
  • Identifying: Although their voice is loud, they are difficult to see. Their coloring of grays to browns, makes for perfect camouflage. The large, dark "X" on their back is a great way to identify them.
  • Subspecies: The Southern Spring Peeper is virtually identical to the Northern species, except for the belly, which has strong, dark markings on it. The belly of the N. Spring Peeper is visually plain.
  • What to look for: Spring Peepers have large "vocal sacs" under their chins. They pump these sacs full of air until they look like a full balloon, then let out a mighty "peep" while discharging the air. The easiest way to see calling Peepers is to look for their shiny vocal sacs, which look like 25-cent pieces, inflating and deflating as they call.
  • Where to find: They are considered a tree frog, but don't usually climb too high off the ground, clinging about a 30 - 40 inches up on trees using their adhesive toe pads.
  • Range:

Spring Peeper Range Map - Courtesy of USGS - Northern Prairie Wildlife Research Center

Source: USGS, Northern Prairie Wildlife Research Center
Checklist of Amphibian Species and Identification Guide

Did You Know?

  • A spring pond full of peeping Peepers can sound like sleigh bells jingling -- only louder.

  • Their Latin name, Pseudacris crucifer, was chosen due for the cross, or 'crucifix' located on the back of this species.

  • The spring peeper produces glucose, or sugar, and "freezes" itself for the winter. In winter, peepers' bodies freeze--but their cells don't rupture because of the concentrated sugars in them. These sugars act as a kind of natural anti-freeze.

  • Their toes have large, sticky pads which help them to cling to tree trunks and climb them quickly.

  • Spring Peepers have one of the largest vocal-sac-to-body ratio of any of the frog species in Maryland. The vocal sac is almost the same size as the peepers body size.

  • The residents of Martha's Vineyard, Massachusetts, call these creatures Pinkletinks.

  • With the possible exception of the bullfrog, the spring peeper is the most popular frog in Maryland.

A Simple Glance at Metamorphosis

Graphic depicting life stages of a tadpole to a frog

For greater detail of the metamorphosis process, visit:
A Frog's Life: Metamorphosis


Maryland Amphibian
and Reptile Atlas Project

"A Joint Project of the Natural History Society of Maryland, Inc. and the Maryland Department of Natural Resources"

Photographs courtesy of John White