Like any apex predator, wolves have a significant impact on their environment. Throughout the nineteenth and twentieth centuries, wolves were hunted to near extinction on the Great Plains. This led to several significant environmental changes as the delicate balance between predators and prey was disrupted.
Without the presence of wolves to keep populations in check, deer, antelope, and even elk proliferated. Without the pressure put on these grazing animals by predators, they gathered at water sources in large numbers. When grazing animals consumed too much erosion-preventing vegetation along the banks of rivers, these waterways changed. They became wider and shallower. This increased the temperature of the water, which led to the decline of many aquatic animals, and particularly trout. Also, wolves have the effect of strengthening herds of deer since they typically target the old and sick. Without wolves, the deer population became less robust, even though it increased in size overall.
Furthermore, overgrazing by animals that wolves traditionally prey upon led to the destruction of smaller animals' habitats. This, in turn, reduced the presence of small prey for other predators, like foxes and raptors. Additionally, without the presence of large carcasses left behind by wolves, the population of many scavenging creatures declined.