For example, declining populations of bald eagles in North America allowed scientists to discover that the environment had been contaminated with DDT, a pesticide used to control mosquitoes and other insects.
For example, declining populations of bald eagles in North America allowed scientists to discover that the environment had been contaminated with DDT, a pesticide used to control mosquitoes and other insects. In this way, the bald eagle served as a warning sign for the environmental damage being done by DDT, allowing a ban on the chemical to be put in place and eagle populations to recover along with the environment.