Summer 2020 Conservationist

Welcome Back

by Dan Thompson, Natural Resources



Image by jeannevc/CC BY-NC


After an absence of nearly 50 years, the Blanchard’s cricket frog has returned to DuPage forest preserves!

The Blanchard’s cricket frog is a member of the tree frog family, which in DuPage includes boreal chorus frogs and spring peepers. Its common name is a nod to well-known herpetologist Frank Blanchard and to the subset of frogs it belongs to, which can jump a bit like crickets. Its skin is typically light brown with dark spots and occasional green highlights; in most cases there’s a dark triangle behind the eyes. Like other tree frogs it has small sticky pads on its toes, but it spends its time on the ground and not in trees, so these pads are not well-developed. Unlike other tree frogs it has bumpy skin that makes it look a bit like a toad.

At 1.5 inches long, though, and with the ability to change color based on its surroundings, the Blanchard’s cricket frog is rarely seen. But now that it’s returned to DuPage, it’s starting to be heard. Males call during the mating season (usually April into summer) to attract females but sound more like insects than frogs. The clicks they make sound like tiny stones or marbles being tapped together.

Blanchard’s cricket frogs live near the edges of lakes, ponds, streams, and marshes, where they primarily feed on small terrestrial and aquatic insects and spiders. Environmentally, they and other amphibians play important roles in the food web, serving as both predators and prey and keeping things ecologically balanced. As predators, they help keep insect populations in check; as prey, they sustain a variety of birds, mammals, reptiles, and other amphibians.

Amphibians as a group are important to humans and the environment. For people, they serve as environmental indicators. Most amphibians have thin skin, which makes them highly sensitive to pollutants and other ecological factors. Negative environmental changes are quickly reflected by an increase in malformations, reproductive problems and population declines. Amphibians also provide a source of biomedicines that can help with a variety of human health issues.

In the 1960s the Blanchard’s cricket frog was considered one of the most abundant frogs in northeastern Illinois, but these small amphibians disappeared quite suddenly. The reason is still unclear, but researchers speculate it was the result of less stringent regulations on pollutants such as PCBs and the use of the pesticide DDT. DDT in particular is well-known for the damage it does to the eggs of birds of prey (think California condors and bald eagles), but it may play an equally detrimental role in declining populations of frogs and other amphibians.

Fortunately, the socially driven environmental movement of the 1970s spurred the establishment of the Environmental Protection Agency in 1972 and the Endangered Species Act in 1973, and DDT and other pesticides were soon banned. This turned around the fate of many species, including the Blanchard’s cricket frog quite likely.

A few years ago, Forest Preserve District ecologists were accompanying their counterparts from the Illinois Natural History Survey through Will County when they spotted Blanchard’s cricket frogs along a corridor that connects Will and DuPage. It took a few years, but Forest Preserve District ecologists and volunteer frog monitors started hearing and seeing the frogs in DuPage forest preserves as well. Volunteers continue to focus on Blanchard’s cricket frogs and play a key role in tracking the amphibians as they slowly spread into additional areas.

Today DuPage has not only Blanchard’s cricket frogs but also bald eagles, ospreys and other birds of prey, all living, breeding and successfully raising young once again. They’re great examples of how we all benefit with a healthier and more ecologically diverse world. As years pass on, the hope is that the sound of tapping pebbles will heard even more.