Researchers around the world have discovered that populations of several species of toads and frogs have declined or completely vanished. This disappearance is thought to be the result of:
- habitat loss and degradation
- loss of atmospheric ozone
- increase in pollution
- overuse of pesticides.
The Northern cricket frog, which once inhabited extreme southern Minnesota, has not been documented anywhere in the state for several years. No one has a clear explanation for why this species, now considered endangered in Minnesota, has disappeared. The decline of spring peepers in the Twin Cities metropolitan area may be linked to the loss of forested wetlands. A Wisconsin study found this woodland species is more likely to breed in wetlands with forests nearby.
Why worry about the loss of toads and frogs?
In addition to being fascinating animals, these amphibians make up an integral part of the food web. Tadpoles eat large amounts of algae and plankton, storing excess nutrients that could otherwise put a wetland out of balance. Amphibians later emerge from the wetland, moving nutrients obtained in the aquatic environment onto land. Toads and frogs eat many insects and, in turn, are eaten by birds, mammals, fish, and reptiles.
These amphibians are also indicators of environmental health or sickness. The permeable skin and dual life existence in both water and land make them highly vulnerable to pollution. The loss of toad and frog populations in various areas of the world is a signal that healthy ecosystems may be imperiled.
Frog deformities have recently received much public and scientific attention. Internal and external deformities of frogs and toads have triggered concern over potential links to human health. Pesticides and other chemicals, ultraviolet radiation, and parasites are among the suspected factors that may be working alone or in combination to cause the deformities.
- Information from 1997-2000 research on deformed frogs found in Minnesota can be found on the Minnesota Pollution Control Agency website.
Anyone who buys frogs from outside of Minnesota must have an importation permit, available from the DNR Section of Fisheries. If you have a toad or frog that is not native to Minnesota, do not release it into the wild. Bullfrogs, although native to the state, should not be released outside of their southeastern range, because they are capable of disrupting local populations of toads and frogs.