The Blanchard's cricket frog is a tiny (7/8 to 1 1/4 inch long, snout to vent), nonclimbing member of the treefrog family which lives in ponds and streams of southwestern Wisconsin. The frog is named for the biologist who first described it, Frank Nelson Blanchard, and for its distinctive cricket-like call.
Male and female Blanchard's cricket frogs look alike, but females are usually larger. Males have a dark vocal sac on their throats that they inflate to help make their mating call. Back color is variable, but is usually brown, gray, olive, or tan, sometimes with a green or reddish stripe running down the middle. Their moist skin has raised reddish spots, or warts. There is a dark triangle or V-shaped spot between their eyes, often rust or lime green in color. Bellies are white and each thigh has dark, ragged crossbars that create a somewhat netlike pattern.
Historically, Blanchard's cricket frogs were found from Southwestern Ontario, Michigan, and Ohio west to Nebraska and south to include most of Texas. Small populations extend into eastern Colorado and New Mexico. Today, this species has almost disappeared from much of the Northern portion of its range, including Ontario, most of Michigan, Minnesota, Wisconsin, Illinois, and Iowa. In Wisconsin, the historical range of the Blanchard's cricket frog was limited to the southern half of the state.
Habitat
Cricket frogs require reasonably permanent water in open country. Open mud flats and stream banks with abundant, low emergent vegetation are preferred. They inhabit marshes, fens, and wet prairies near permanent or flowing water. In lakes and ponds they prefer aquatic sites where submergent vegetation grows along the shorelines. They need soft muddy bottoms to hibernate in through the winter.
Habits
Cricket frogs live mostly on the edges of ponds and streams with submerged or emergent vegetation. Look for them sitting on aquatic plants or sitting at the water's edge.
Cricket frogs can leap great distances, despite their small size. With long legs that are over half of their extended body length, cricket frogs can jump more than three feet. That's like a six foot tall person jumping 200 feet! Cricket frogs escape predators (e.g. fish, snakes, herons, mink) with a quick series of zig-zagging, erratic leaps.
Cricket frogs are cold-blooded. This means that they cannot maintain a steady body temperature like birds and mammals. To survive Wisconsin's freezing winters, they hibernate from late November until late March.
Life History
Cricket frogs are mostly diurnal (active during the day) in spring and fall, but also nocturnal (active after dark) in May through July when males call night and day to attract mates. Their distinctive mating call sounds like steel marbles clicking together. It starts slowly, accelerates, then slows down quickly.
Cricket frogs are sexually mature when one year old. They breed in late May to late July. A male will mate with any female that approaches him. He grasps her body, stimulating her to release eggs while he releases sperm. The eggs are attached to submergent vegetation in clumps of 10 - 15 and are fertilized outside the body. A single female may lay up to 300 eggs. Eggs hatch in a few days into tiny tadpoles (0.4 inches long) that have a black-tipped tail. No other tadpoles have this trait. Tadpoles metamorphose (change) between late July and late August. The average lifespan of an adult cricket frog is four months. This very short lifespan means that the entire population can turn over in only 16 months.
Frogs, along with toads and salamanders, are amphibians. "Amphibian" means "double life," a name given to these animals because, with few exceptions, they spend part of their life cycle in water and part on land. Frog eggs hatch into tadpoles which live in the water. Tadpoles metamorphose from gilled animals into air-breathing adults that are able to live on land.
Food Habits
Blanchard’s cricket frogs mostly eat tiny insects including beetles, spiders, midge larvae, water boatmen, springtails, and small slugs and crickets. They feed both day and night and consume large numbers of prey. One study estimated that in Wisconsin, 100 cricket frogs living around a small pond would consume 480,000 insects and other small vertebrates in one season.
Status in WISCONSIN
Prior to 1970, Blanchard’s cricket frogs were quite common in southern Wisconsin. Then the population declined rapidly. During the 1980s, biologists and volunteers found no cricket frogs in many of the sites where they existed previously. A 1991 survey of 40 historic cricket frog sites found that only 19 of those sites were occupied by cricket frogs. In a 1994 follow-up study of 24 sites (including 12 sites active in 1991) only 5 were active. None of the sites had strong populations. However, two new sites, with fairly large cricket frog numbers, were discovered in 1994. In recent years this frog has been documented in three southwestern Wisconsin counties; Grant, Lafayette, and Iowa.
While the cause of this dramatic decline is not certain, it is known that cricket frogs can't survive in polluted water. Several factors are suspected to be involved, including drought (especially during winter), increased amounts of pesticides, fertilizers, highway salts, and other pollutants that degrade water quality and the loss or fragmentation of wetlands in the southern part of the state. The tremendous flooding of 1993 which resulted in the flushing of several key rivers twice during cricket frog breeding is suspected to be the cause for the most recent declines. Low populations and a very limited life span will severely limit recovery.
Because of the rapid decline in their numbers and their low population, Blanchard's cricket frogs were placed on the Wisconsin Endangered Species List in 1982. Only a few hundred cricket frogs are currently estimated to exist in the state.
Research and Management
Since frogs are sensitive to changes in water quality, they can serve as indicators of environmental problems. As the cricket frog populations decline, concerns about the deteriorating condition of their habitat increase. In 1981, the Wisconsin Frog and Toad Survey was initiated to determine the abundance and distribution of frogs and toads in the state, and to assess the quality of their wetland habitats. This study was expanded in 1984, becoming a statewide volunteer program designed to obtain long-term information about Wisconsin frog and toad population trends.
While no cricket frog management plan has been developed, the DNR encourages citizens to reduce the use of environmental contaminants that get into the water supply, and discourages the destruction of the wetlands so critical to the survival of Blanchard's cricket frogs and other Wisconsin wildlife.
What You Can Do
The Wisconsin Frog and Toad Survey requires the assistance of many people. Volunteer observers survey select wetland sites three times during the frog and toad breeding season. Observers listen for the distinctive calls of Wisconsin’s twelve species of frogs and toads, and record information about species presence and estimated abundance. If you are interested in becoming a long term volunteer observer, contact the BER at the address given below.
Maintaining the existence and quality of Wisconsin's wetlands is essential to the survival of many wetland plants and animals. Wetlands also help humans by filtering and helping to purify our ground water. To find out more about the importance of wetlands and how to prevent and solve the problem of water pollution and wetland destruction, contact the DNR and your local government and environmental organizations.
Endangered Resources Reports
For more information about Blanchard's Cricket Frog, see the reports by topic Blanchard's Cricket Frog reports.
To order any of these reports, please e-mail your request to
Bureau.EndangeredResources@dnr.state.wi.us.
SOURCE:
http://www.dnr.state.wi.us/
