Baleen whale species migrate annually, with many following a predictable pattern. In particular, both humpback and gray whales have notably long migrations. Both species have migrations that total over 10,000 miles round trip, with the longest recorded migration being a 13,988 mile journey by a gray whale from Mexico to Russia and back. These animals have not only the longest migrations for whales—it is the longest migration for any mammal.
Caption: Migratory Routes of the Humpback Whale (from Off the Map Travel website)
Animals migrate for a variety of reasons, including following food sources and giving birth. Along the Massachusetts coast, several species, including humpbacks, arrive in the spring to feed on large populations of small fish and zooplankton throughout the summer. These animals had spent their winter months in the Caribbean where the water is warm, but the ecosystem doesn’t provide much, if anything, to eat.
Conversely, many whale species dedicate their winter months to breeding and calving. In these months, whales migrate to warm tropical climates to give birth, as the calves have only a thin layer of blubber. Being born in warmer water puts less stress on their bodies.
Because whales have the ability to metabolize energy from the oil in their bone marrow and from blubber, certain species of whales can go months without eating while living off these energy reserves. They build up their reserves during the many hours of daily feeding during the spring and summer. In fact, they may eat as much as 4% of their body weight each day during the summer.
Some whales exhibit different migration patterns based on sex and/or age. For example, for right whales, it’s mainly the pregnant females who migrate. However, for humpback whales, both sexes are seen migrating. Calves will stay with the mother to nurse until they can hunt on their own, at which point they follow their normal migration cycle (around one year for baleen whales to be weaned).
On the other hand, most toothed whales are not thought to have set migration patterns. In sperm whales, the females and calves will stay in the breeding grounds close to the equator their whole lives. Male sperm whales have been found to wander the colder areas of the oceans alone, except for when breeding.