Illinois Chorus Frog - Pseudacris streckeri illinoensis
The Illinois chorus frog may at first appear more like a toad with its stout body and thick forearms. It is a secretive frog that lives in open, sandy areas that were formerly sand prairie grasslands and wetlands of southeastern Missouri. Except for spring courtship, this frog lives underground most of its life. The main threat to its survival is draining and clearing of sandy wetlands. The Illinois chorus frog is listed RARE by the Missouri Department of Conservation and is currently a candidate for federal listing by the U.S. Fish and Wildlife Service.
Identification
![[line drawing of Illinois Chorus Frog]](images/frog2.gif)
The Illinois chorus frog has an average length (body and head) of 1 to 1 1/2 inches. It is tan to tannish-gray with a white belly and many dark brown or gray irregularly-shaped markings on its body. This frog has a distinguished "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 in color 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.
For a technical description of this animal, refer to:
Johnson, T.R. 1987. The Amphibians and Reptiles of Missouri.Missouri Department of Conservation. Jefferson City, Missouri. 368 pp.
Habitat and Distribution
![[Missouri map of Illinois Chorus Frog distribution]](images/frog3.gif)
Illinois chorus frogs live in sandy grasslands, wetlands, and agricultural areas of the Bootheel. In late winter, they prefer temporary pools in herbaceous wetlands, bottomlands, and floodplains. Wetland draining and habitat changes have forced them to use alternative habitats such as flooded roadside ditches, cultivated fields, flooded pastures, cattle ponds, sloughs, and small remnant wetlands.
Illinois chorus frogs are fossorial, which means they are adapted to digging and burrowing. The Illinois chorus frog uses its front legs to burrow in the sandy soil. They emerge from their burrows only to breed during late winter and occasionally to feed during summer rains. Courtship begins in February, and may continue into early April. Frogs are stimulated to migrate between their burrowing areas and the breeding pools when heavy rains occur and temperatures exceed 48 degrees Fahrenheit. The breeding call of the males is a distinct high-pitched series of rapid, bird-like whistles. Most calls begin after dark and continue into the night.
Females lay numerous clusters of eggs. Tadpoles develop into sub-adult frogs by May or June. The tadpoles eat suspended matter, organic debris, algae, and plant tissue, while adult frogs eat small insects and burrowing insect larvae.
Historically, the Illinois chorus frog occurred throughout sandy grasslands in southeastern Missouri. The present range of the chorus frog includes isolated populations associated with specific soil types in Mississippi, Scott, Dunklin and New Madrid counties. The following soil types offer chorus frog habitat: Clana-Malden in Mississippi county, Scotco and Clana-Malden in Scott county, Crevasse-Canalou and Basket-Broseley-Dubbs in New Madrid county, and Malden-Canalou-Basket and Dundee-Silverdale in Dunklin county. The chorus frog's former range included Pemiscot, Stoddard, and Cape Girardeau counties.
Cause of Historic Decline
Historical changes in habitat resulting from channelization, the filling of wetlands, the conversion of sand prairie to agricultural fields, and highway construction were reasons for the original concern and candidate status of this reclusive frog. However, recent surveys suggest that the frog is locally abundant and that populations are stable. Current farming practices do not appear to harm or to further reduce frog populations. Management efforts should be focused on creating sand prairie grassland habitat or improving existing areas.
Current Threats To Illinois Chorus Frogs
- Insecticides and herbicides The application of these chemicals near water is harmful to chorus frogs and other aquatic wildlife. Frogs collected in Scott County had significant residue levels of hetachlor epoxide and trace amounts of dieldrin and DDE on their bodies. High concentrations of pesticide could harm frog eggs or could directly affect the survival of adult frogs.
- Conversion and clearing of wetlands, sand prairies, and bottomland forests These practices destroy optimal chorus frog habitat. Although chorus frogs seem able to survive in agricultural habitats, the maintenance of a diversity of habitats suitable to frogs is beneficial. It is unlikely that these substitute agricultural habitats are optimum for the frogs.
- Draining and filling wetlands When habitats ideally suited for chorus frogs are destroyed, frogs are forced to use less than optimal habitat. This may result in higher mortality, lower reproductive rate, and reduction in population size.
Protection and Management: Steps Toward Recovery
- The construction of fishless pools in Clana-Malden, Scotco, Crevasse-Canalou, Basket-Broseley-Dubbs, Malden-Canalou-Basket, and Dundee-Silverdale soils in southeast Missouri provides breeding habitat for the chorus frog and other wildlife. Only pools located on these soil types will provide beneficial breeding habitat. Ideally, pools should be constructed so that 1/3 of the bank slopes gradually toward the deepest point of the pool. Pools should be no smaller than 30-40 feet across, and the deepest part should be two feet. Brush piles and tree brances placed in the shallow water provide cover and a suitable place for frogs to lay eggs. If possible, fencing should be placed around the pool approximately 20 feet from the pools' edge. Fences exclude cattle, thereby limiting soil erosion and promoting the growth of aquatic plants.
- Limit the use of pesticides near aquatic sites and on sandy soils, particularly during the early spring. High concentrations of toxins in the water may affect the breeding success of the frog. Caution should also be used when applying pesticides in areas where runoff will cause the pesticides to collect in low-lying areas that fill with water and are used by the frog for breeding.
- Avoid converting wetlands and native prairie into cropland and pastures. Although chorus frogs survive in agricultural fields, they are more suited to natural habitat for breeding and burrowing.
- Improve existing pools by planting sand prairie grasses. Keep small, shallow pools fishless and limit access to the pools by cattle.
For more information on the Illinois chorus frog, or to report sightings of this species, contact:
Endangered Species Coordinator or Wildlife Ecologist Missouri Department of Conservation Natural History Division P.O. Box 180 Jefferson City, MO 65102 573/751-4115
For more information on pasture improvement programs or additional information on Illinois chorus frog management, contact:
Your Local Natural Resources Conservation Service Office
