Predators include the wolf, artic fox, and snowy owl. Polar bears, and sometimes brown bears are seen. Many birds nest in the tundra shrubbery in summer, migrating to milder climates before the winter season sets in. Invertebrate life is scarce, but insects such as black flies and mosquitoes are abundant. Alpine animal life includes the mountain goat, big-horned sheep, pika, marmot, and the ptarmigan, a grouselike bird.
Flies are scarce but butterflies, beetles, and grasshoppers are abundant.
The tundra ecosystem is extremely sensitive to disturbance with little ability to restore itself. Disruption of vegetative cover causes permafrost to melt deeply, causing collapse of ground and loss of soil. Automobile tracks cause deep gullies that persist for years. The tundra wildlife is vulnerable to habitat destruction, to overhunting, and to extinction through loss of any of the animal or plant species that make up the fragile, highly individual tundra community of life. The number of plant species on the tundra is few, and their growth is low, with most of the biomass concentrated in the roots.