 When there is a significant amount of snow, moose stay in conifer swamps, making them easier prey for wolves, because they are more confined, and immobilized due to the snow.Deep or heavy snow decreases the speed and agility of moose that is necessary to evade wolf attacks, and calves born during a winter with particularly deep snow are more vulnerable to being weaker prey for wolves later on in their lives because of foraging problems that occur when the snow is deep.The keen survival instincts of moose have been clearly evident from the studying of their actions on Isle Royale.