Leopard frogs are more tolerant of the cold then many other amphibians. This has allowed them to survive in colder climates and claim a more northerly range, up into the middle of Canada. However since the 1970 their population has been on a steep decline. Most people believe that this is probably due to pollution and the chemicals that can be found in many waterways. Collection of leopard frogs for school dissection projects as well as consumption, some people consider frogs legs a delicacy, has also added to their decline.