 Most mysticetes reside at the poles . So , to prevent the unborn calf from dying of frostbite , they migrate to calving / mating grounds . They will then stay there for a matter of months until the calf has developed enough blubber to survive the bitter temperatures of the poles . Until then , the calves will feed on the mother 's fatty milk . With the exception of the humpback whale , it is largely unknown when whales migrate . Most will travel from the Arctic or Antarctic into the tropics to mate , calve , and raise during the winter and spring ; they will migrate back to the poles in the warmer summer months so the calf can continue growing while the mother can continue eating , as they fast in the breeding grounds . One exception to this is the southern right whale , which migrates to Patagonia and western New Zealand to calve ; both are well out of the tropic zone . 
