Summer mortality among caribou calves in West Greenland.

Colibacillosis with polyarthritis, due to E. coli O-group 55, has been found to be responsible for a high summer mortality among caribou valves in West Greenland. The mortality is presumably consequential on overstocking and therefore likely to subside as the caribou population in the preferred habitats is reduced to a lower density--the optimum level of which is as yet unknown.