Cattails are one of the favorite foods of muskrats. If a pond is taken over by loosestrife, cattails die and muskrats will leave the pond. . Going Wild Sometimes domesticated animals like cats, dogs and horses become wild or feral. Feral animals can cause problems for native plants and animals. Some plants in Hawaii are endangered because feral pigs eat them and destroy them by rooting around for food.
Feral cats can kill native birds.
They are especially dangerous to ground-nesting songbirds. Some exotic species are introduced by accident. The zebra mussel is native to the Balkans. The Balkans are in South Central Europe. It was brought to the US when ships dumped their bilge water.