Dead moose

A guy is walking around a snow covered lightly wooded area with hills and mountains he comes across 200 moose dead on the ground. no wounds no nothing but they are all dead... he wonders how did this happen. another man shows up on a snowmobile ignores the man and ties a rope around one of the moose to carry it off for food.. the original man asks the other man, did you kill them? the other man says no. so he asks, how did they die then? the other man replied, they drank too much. the man confused by the other mans answer asks, drank too much? the other man says yes and drives away.
so how did the moose die?