It is mid-March, somewhere in the mid-Atlantic states. Little, if any, snow is on the ground. But a person who ventures forth at dusk may hear the sound of distant sleighbells. In fact, it is a chorus of tiny frogs: spring peepers.
Literary scholar and naturalist Joseph Wood Krutch, in a collection of essays titled The Twelve Seasons, expressed in delightful fashion his opinion that a spring peeper chorus, not the arrival of the first robin or appearance of the first crocus, was the truest harbinger of spring.
Male spring peepers, no bigger than the first thumb joint, produce the loud, bell-like calls each of which is a single note ending with an upward slur. In t his manner the males urgently beckon the slightly larger females to the ponds--permanent, or more generally, temporary--that serve as breeding sites. The inch-long males have hopped their way from wooded tracts through varied landscapes, perhaps over a distance of half a mile (about 32,000 inches!) to reach these ponds. Now they wait as females make the same impressive trek.
Sounds of this chorus carry almost half a mile. This fact supports the view of a pioneering herpetologist, G.K. Noble, who believed that amphibians in temporary ponds have louder voices and shriller calls than species (such as bullfrogs) that dwell in permanent ponds or lakes. Mating and larval development must be completed before the ponds disappear with the heat of the summer.
The spring peeper is one of roughly 600 species of frogs that have been given the family name Hylidae. Tree frogs, whistling frogs, and chorus frogs are common names of other members of this family. All of them have distinctive expanded toe tips with sticky adhesives pads. Cartilage between the terminal two bones of each toe facilitates swiveling motion sideways and backward.
The peeper can generally be identified by a black, X-shaped mark on its back. This feature inspired its Latin species name, crucifer. The genus name was Hyla until a few years ago, when taxonomists changed it to Pseudacris.
The oblique dorsal cross is most readily visible on those peepers whose bodies are tan, olive, or gray and less visible on individuals whose body color is darker brown. Irregular, black or brown bars and blotches mark the limbs, especially the hind limbs. Among the northern subspecies, P. crucifer crucifer, the belly is an unmarked white to pale yellow, while individuals of the southern subspecies, P. crucifer bartramiana, have a spotted belly.
The family Hylidae belongs to the ancient clan Amphibia. This class of vertebrates was the first group to solve the challenges of life on land. Fossil evidence indicates that amphibians emerged in the late Devonian period, about 350 million years ago. Today, the three main groups of amphibians--salamanders, frogs, and toads--are found worldwide but, as is true of other poikilotherms (animals with variable body temperature), the majority dwell in tropical and temperate regions.
The range of the northern spring peeper extends from the Canadian Maritime Provinces to Manitoba, south through the northern and mid-western regions of the United States to the Gulf Coast and most of the southern United States. The southern subspecies is found in southeastern Georgia and adjacent northern Florida.
Male peepers call from secluded sites, positioning themselves among grass tufts or woody shrubs just above the surface of temporary or permanent ponds, water-filled ditches, or shallow pools. In the southern regions, choruses begin at dusk from November through March. But for residents of the mid-Atlantic states and northward, the chorus that signals spring begins in mid-March and continues until early June. Early in the season, the chorus seems to coincide with warm evening rains. Later, desperate males sing day and night in hopes of mating with late-arriving females.
Take time to listen to the chorus. …