There are 15 invasive species that threaten tundra biomes, according to the Global Invasive Species Database, including Canada geese, dogs, cats, beavers, weasels, sheep, red foxes, European starlings and pine trees. Invasive species in the tundra push away native flora and fauna and reduce diversity in tundra biomes.
Canada geese are invasive to the tundra because they are overpopulated and have no local predators. These birds migrate and settle in tundra biomes, and that can be detrimental in terms of food supply and fecal waste in the environment, according to the Global Invasive Species Database.
Dogs, cats, weasels and foxes prey on tundra animals and affect food supplies for native predators. Birds and small mammals are eaten by these invasive species and are threatened by lower numbers. These crafty animals hide from higher order predators in order to survive.
Pine trees take over the land and reduce native vegetation. Trees are planted to enhance forestry products, but they destroy lesser plants that rely on scarce tundra resources such as food and sunlight.
Starlings compete with native birds for food and shelter, thereby reducing tundra bird species. Starlings migrate rapidly and reproduce quickly, so their populations increase faster than native birds.
Wild sheep have decimated local grasses and plants on several tundra islands. These sheep also push away other mammals vying for food.