Illinois Chorus Frog

Pseudacris illinoensis
Species of Conservation Concern
Family

Hylidae (treefrogs and allies) in the order Anura (frogs)

Description

The Illinois chorus frog is tan to tannish gray with a white belly and many dark brown or gray irregularly shaped markings. This frog has a distinctive V-shaped marking between the eyes, a dark stripe from snout to shoulder, and a dark spot below each eye. Young froglets are dull gray and have inconspicuous body markings. The skin of the Illinois chorus frog has a rough texture. The large and muscular forearms of this frog are used to dig the burrows where it spends much of the year. The webbing on the hind feet is poorly developed. The males’ breeding call is a series of high-pitched, rapid, birdlike whistles.

Size

Body length: 1 to 1½ inches.

Habitat and conservation

Sandy grasslands, wetlands, and agricultural areas of the Bootheel. Habitat changes resulting from channelization, filling of wetlands, conversion of sand prairie to agricultural fields, and highway construction were reasons for the original concern and candidate status of this reclusive frog. Management efforts should be focused on creating sand prairie grassland habitat or improving existing areas.

Foods

The tadpoles eat suspended matter, organic debris, algae, and plant tissue. The adult frogs eat small insects and burrowing insect larvae.

image of Illinoise Chorus Frog Distribution Map
Distribution in Missouri

Historically, the Illinois chorus frog occurred throughout sandy grasslands in southeastern Missouri. Its present range includes isolated populations associated with specific soil types in Mississippi, Scott, Dunklin, and New Madrid counties.

Status

Listed as imperiled by the Missouri Department of Conservation and is currently a candidate for federal listing by the U.S. Fish and Wildlife Service. It occurs only in parts of Illinois, the Missouri Bootheel, and one county in extreme northeastern Arkansas. Formerly considered a subspecies of the Strecker’s chorus frog, in 2004 the Illinois chorus frog was given full species status.

Life cycle

This secretive frog emerges from its burrow to breed in late winter, then again to feed during summer rains. Courtship begins in February and may continue into early April. Frogs are stimulated to migrate between burrowing areas and breeding pools when heavy rains occur and when temperatures exceed 48 degrees Fahrenheit. Females lay numerous clusters of eggs. Tadpoles develop into subadult frogs by May or June.

Human connections

Agricultural development in the Bootheel has destroyed nearly all the natural ephemeral pools where this species formerly bred, and housing development has nearly eliminated the sand prairie. This frog still lives in some highly cultivated areas but may not survive continued habitat destruction.

Ecosystem connections

Ecosystems have been likened to jets, and species as the plane’s components. If a species of gnat, violet, or frog disappears, it might be like losing a rivet from a wing. A few missing rivets may not affect the jet’s safety — but at some point, if enough components disappear, it will crash.