The Illinois chorus frog (''Pseudacris illinoensis'') is a species of
chorus frog that lives in scattered, restricted habitat ecosystems in the states of
Arkansas,
Illinois, and
Missouri. It was published by Smith in 1951. Its life cycle is little known, its isolated populations are increasingly restricted by agricultural drainage, and it is listed as a
threatened subspecies.
[Jeanne Townsend Handy, "The Secret Life of the Illinois Chorus Frog", ''Outdoor Illinois'' XIX:3 (March 2011), pages 9-11.] It is often referred to as a subspecies of
''P. streckeri''. Collins recognized it as its own species which was followed by ASW6.0 and Amphibiaweb on the basis of its diagnosability from Pseudacris streckeri and its allopatry. The IUCNredlist 2013.2 has not incorporated this taxonomic split.
Description
The Illinois chorus frog, a
wetland amphibian
Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...
, grows to a maximum length of . Its range is restricted to isolated sandy wetlands along the banks of the
Mississippi River and a major tributary, the
Illinois River
The Illinois River ( mia, Inoka Siipiiwi) is a principal tributary of the Mississippi River and is approximately long. Located in the U.S. state of Illinois, it has a drainage basin of . The Illinois River begins at the confluence of the D ...
.
Its life cycle begins with the
mating season beginning in late February and continuing until late April, when the small amphibian signals its aptitude with a version of the distinctive cry that gives its genus its name. The breeding call can be heard at a distance of up to . The pools of spring
meltwater
Meltwater is water released by the melting of snow or ice, including glacial ice, tabular icebergs and ice shelves over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing. Meltwater can be ...
, where they live and eat, begin to dry up as early as mid-May, and the frogs disappear into
hibernation
Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most ...
below the winter frost line. With unusually strong
forelegs for its size, the Illinois chorus frog is described as the only frog that uses a
breast stroke
Breaststroke is a swimming style in which the swimmer is on their chest and the torso does not rotate. It is the most popular recreational style due to the swimmer's head being out of the water a large portion of the time, and that it can be s ...
motion to dig its sandy burrows.
Threats
The Illinois chorus frogs' preferred habitat in Arkansas includes the patch of sandy wetland soil surrounding
Stuttgart, Arkansas
Stuttgart is a city in and the county seat of the northern district of Arkansas County, Arkansas, United States. Established by German settlers, it was named for its larger German counterpart. Known as the "Rice and Duck Capital of the World", t ...
where
rice is grown. However, the invention of
laser land-levelling, and its use by
rice paddy operators, has eliminated 61% of the subspecies' range in this southern state.
Current events
The
Illinois Department of Natural Resources carried out a field study of the Illinois chorus frog's habitat in
Mason County, Illinois, in March 2011. The study hoped to develop a methodological protocol to monitor the Illinois chorus frog's threatened population.
[Chris Young, "Researchers listen for chorus frogs", '' The State Journal-Register'' (March 28, 2011), pages 8, 12.]
References
{{Taxonbar, from=Q16925014
Amphibians of the United States
Chorus frogs
Amphibians described in 1951