So if an area is overgrazed or burned the caribou won't be able to use that habitat for many years. In fact, there have been fires in northern Manitoba within this herd's winter range and we're concerned how this might affect their use of the area. In the wintertime, caribou obtain the lichens by 'cratering' through the snow. When we go out for field studies in late March we've seen instances where they've cratered through snow as much as 2 feet deep. In most winters they can forage without difficulty but some years starving can occur if an icy cover forms and prevents them from obtaining food easily.
Many lichens are very sensitive to pollution in the air.
When there are too many harmful things in the air, lichens die. They can tell us if the air is clear and clean. Even in the remote arctic, pollution has contaminated lichens. Through studies of arctic women who are nursing their babies, these contaminants are known to even reach babies when they drink their mother's milk. Write a vacation postcard from a manatee to a caribou.