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One thing leads to another. Dennis Skadsen and I were collecting clam shells on a warm September day along the Big Sioux River in Union County. Suddenly Dennis locked his eyes on movement along the shoreline and whispered "what kind of frog is that?" Although I had never seen a frog like this either, my first guess was that it was a northern cricket frog, having the advantage of recently reading about this species and how it was disappearing from places it was once common. We captured one and after checking our field guides confirmed that it was indeed a northern cricket frog, Acris crepitans.

The northern cricket frog is reported to be disappearing from many portions of its northern and western range. It is state listed as endangered in Wisconsin, Michigan, and Minnesota. Major losses in range are reported in Illinois. Northern cricket frogs may be gone from Ontario. This species once occurred in ten counties in southeastern South Dakota but until we found the frogs on the Big Sioux River in the fall of 2000 the cricket frog had not been reported anywhere in South Dakota since 1972. It was also common along the Keya Paha River in Tripp County as recently as 1967 but is now apparently gone from that area. Since there had been several recent attempts to locate northern cricket frogs in South Dakota, without success, I was pleasantly surprised to find these frogs.

This is one of the smallest frogs that occur in the northern plains. The species has a wide distribution across much of the eastern and southern United States and formerly into southern Ontario. Cricket frogs can be abundant in their preferred habitat of well-vegetated ponds and streams. Breeding occurs later than in most species of frogs and toads, in South Dakota the peak of the breeding season appears to be in late May and early June. As frogs congregate in suitable breeding wetlands the males begin calling. Male cricket frogs have a call that can best be described as someone clicking two rocks rapidly and repeating over and over. Females may lay up to 400 eggs, singly or in groups that attach to submergent vegetation. The tadpoles undergo metamorphosis in one to two months after hatching. Although tadpoles feed on algae and small aquatic invertebrates, adult are completely carnivorous, feeding mostly on insects. Renowned for their jumping ability, these small frogs, reaching a maximum of 1.5 inches in length, can easily leap a distance of three feet or more.

Cricket frogs are active late into the fall until cold weather drives them into their hibernation sites. The winter is spent in crayfish burrows, cracks in mud, and other protective holes along the streams and ponds they inhabit. They do not hibernate in the water of the streams and ponds, as leopard frogs do. However, this species is not freeze tolerant like tree frogs, chorus frogs and wood frogs, which also hibernate in terrestrial habitats, not in water. Freeze tolerant frogs freeze solid in winter then revive in the spring. They have evolved physiological traits that allow them to survive being frozen. Cricket frogs cannot do this. Cricket frogs must hibernate in terrestrial sites that provide protection from freezing temperatures and so are probably existing at the northern limits of their range in southeastern South Dakota. Our discovery of cricket frogs on the Big Sioux River was intriguing but I had no time to investigate further.

When Ron Wilmot, a science teacher at Akron-Westfield Community School in Akron Iowa, contacted me about our Wildlife Diversity Small Grants Program I suggested a cricket frog project and Ron jumped on the idea. Ron and his students surveyed the Big Sioux River valley in Union County in the spring and summer of 2001. Using a technique that is popular in many states, Ron and the students ventured out at night to listen for calling frogs along established routes and sites. Frog calls are easily identified by comparing them to taped calls. In addition, the students captured some cricket frogs and photographed them for verification of their records. They identified ten species of frogs and toads, including northern cricket frogs. The cricket frogs were found at nine of thirty sampling sites. Cricket frogs were most common in the river flood plain.

Meanwhile, Ricky Olson, a naturalist from Pierre and also funded with a Wildlife Diversity Small Grant, was looking for cricket frogs in Tripp County, along the Keya Paha River and wetlands. Although cricket frogs were common along the Keya Paha River as recently as 1967, Rick’s work showed that cricket frogs are no longer found in that part of South Dakota.

Going into the fall of 2001, all the available evidence indicated that cricket frogs were only surviving in the extreme southeast corner of South Dakota. Prior to learning about the frogs on the Big Sioux River, this species appeared to be extirpated from the state. A research project out of South Dakota State University that surveyed east west transects of eastern South Dakota for frogs and toads, using calling surveys, detected no northern cricket frogs in 1997 and 1998. In 1995, a researcher from Drake University checked all of the historic collection sites in South Dakota and found no cricket frogs.

One thing leads to another. Just this fall, I was collecting clam shells, this time along the James River in Yankton County. I collected at many different sites, but at one location, a small Game Production Area owned by the South Dakota Department of Game, Fish and Parks, a small frog leaped mightily from the muddy riverbank into the water. It was cricket frog! I eventually found several more in this area and north into Hutchinson County, all along the muddy banks of the James River.

The decline of cricket frog has rang the alarm bells in some states, since no one seems able to explain the losses. It may be just a simple matter of natural range contraction and expansion at the periphery of the range. At this latitude, a few years of poor conditions, especially in winter, could knock populations down to low levels or just wipe them out. Now, cricket frogs may be recolonizing river bottoms in eastern South Dakota. Or, are these just remnant populations that are clinging to survival? If so, why? Is there is an environmental problem? The only way to answer these questions is to continue monitoring species like the northern cricket frog and other rare species in our state. Without good information, good decisions cannot be made.