Migration

Many species of cetaceans, including all baleen and many toothed whales, are migratory. They travel long distances between breeding grounds and feeding areas. Whales migrate for basically the same reason as other animals: to avoid biologically stressful climatic conditions. Whales spend the summer months in areas with plenty of resources to satisfy their enormous appetites. These areas are often located in higher latitudes, far away from the equator. When winter comes, these whales leave the colder waters for more temperate areas closer to the equator. Migration to warmer water allows them to give birth to calves with less risk. Calves are born without insulation and would lose body heat rapidly, risking death, if they were born during winter in high latitudes. However, this benefit for calves has a price for adults. In warmer waters, the food supply is reduced to almost zero. Adult whales may lose enormous amounts of their body weight, in humpback whales up to 10-15%, before returning to feed again in the summer. Bowhead whales, natives of the high Arctic Ocean, migrate east to west rather than north to south, but the reasons remain the same. Some species have well known migration patterns and others less so. The humpback whale is very well known because it inhabits areas close to shore in both summer and winter. Other species, like the blue, fin and minke, are harder to find because they head out into the open ocean in winter. Scientists still do not know where some whales go for almost six months of the year!