Answer:
Overgrazing, Intraspecific competition, Low amounts of food, and Ecological disturbances.
Step-by-step explanation:
The mass die-off of reindeer on St. Matthew Island during the winter of 1963-64 appears to have been caused by a combination of factors:
(1) huge numbers of reindeer overgraze lichens on the island, which are traditionally the most significant winter feed;
(2) a large number of reindeer fighting for the relatively limited available fodder during the die-winter; off's
(3) the reindeer's comparatively low winter condition as a result of competition for high-quality summer fodder during the summer of 1963; and
(4) During the winter of 1963-64, adverse weather conditions, notably substantial snow accumulation, further limited the availability of the already decreased winter fodder.