Many animals over the years have become endangered due to human activity by introducing nonnative species.

In the Great Smoky Mountains from 1934 to 1975, the National Park Management would add species of fish like the rainbow trout and the brown trout into the Great Smoky streams.  They used these trout as game fish.  However, the regions native trout which was the brook trout already inhabited those streams.  The native trout has been striving to survive since the nonnative (rainbow, brown) trout has taken over most of its habitat. 

Many of the salamander species have also become endangered due to wild hogs that have entered the Great Smoky Mountains National Park in the 1920's.  In the 1920's many of the wild hogs escaped from a local game farm.  They eat mostly everything insight including rare salander species.

An Asian fungus called Chestnut Blight during the 1900s has also affected animal species to become endangered.  The Chest Blight affected chestnut trees killing them all around the Appalachian area.  It was first detected in 1904 in New York City.  The chestnut trees were not immuned against the asian fungus.  Several years later in 1950, the chestnut trees were completely wiped out causing them to become extinct.  Many animal species were affected by the extinction of the chestnut trees.  The chestnuts were some of the animals main source of food. Some of those animals were the ruffled grouse, wood ducks, and wild turkeys. The chestnut blight affected the forest birds the most by destroying their habitat; causing many of them to become endangered.