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Baleen whales are some of the most unique and breathtaking animals in the world. These huge marine mammals are some of the largest ever and can be found all over the world. Despite their size, these gentle giants are famous for eating only the smallest animals around. What’s more, they are known for making some of the longest migrations of any animal. Here we will find out exactly why baleen whales migrate and where they go.
What are baleen whales?
There are fourteen species of baleen whales, including blue whales, bowheads, right whales, fin whales, humpback whales, minke whales, and gray whales. Baleen whales are whales that have “baleen plates” instead of teeth. These mustache plates are made of keratin and grow in rows on either side of the mouth. They have bristles that act as a filter when the whale is feeding. The length of the whalebone varies from species to species, with the right whale having the longest of them. Baleen whales have two airways rather than one, and they are usually much larger than their toothed cousins. The blue whale is the largest animal that ever existed and is known to grow to a whopping 110 feet in length.
Baleen whales primarily feed on krill, plankton, and small fish. They feed by taking large gulps of water, which is filtered through whisker plates, in which krill or fish are caught, which are then swallowed by whales. Baleen whales have two feeding methods – fat-free feeding and lunge feeding. When they feed on lean meat, they slowly swim through schools of fish or plankton with their mouths open to catch a gulp of food. However, some species – such as the blue whale – feed on lunges and jump at great speed over huge clouds of krill to feed in massive numbers.
Unlike toothed whales, baleen whales usually live alone or travel in small groups rather than in large social herds. They do not use echolocation; instead, they communicate using low-frequency sounds known as “songs” that can travel long distances. Even though they are solitary animals, they are usually always within the reach of other members of their species. It is believed that these communication songs are used to warn of danger and find each other for mating.
Where do baleen whales migrate to?
Although baleen whales are found in all major oceans, they migrate far. Many species of baleen whales migrate annually from cold water feeding grounds, where they spend the summer, to warm water breeding grounds for the winter. Their feeding grounds are areas at higher latitudes, closer to the poles, where water is colder and food is much more, and breeding grounds are closer to the equator.
In the summer, baleen whales typically spend four to six months in the rich feeding areas of polar waters. During this time, they eat about 4% of their weight every day, which is much more than they need. All of this excess energy is stored as fat in a thick layer of blubber to keep it going through the winter.
In winter, baleen whales spend six to eight months cruising tropical waters and giving birth. All this time, baleen whales eat much less or even do not eat at all, as there is much less food. On average, they eat only 0.4% of their weight per day in winter, relying instead on the fat they have accumulated during the feeding season.
Why do baleen whales migrate?
The main reason for the migration of baleen whales is that they can give birth in warmer tropical waters. When baleen whale babies are born, they have an underdeveloped blubber, which is the layer of fat that keeps them warm. Since their fat is not fully developed, it is not thick enough to warm them in colder water. This means that cold water can kill them. Thus, when giving birth in warmer water, calves have ample time to build up a thick layer of subcutaneous fat before returning to the cold water feeding area.
Another reason baleen whales migrate to give birth in warmer waters is to protect their young from killer whales. Killer whales are one of the main predators of baleen whale cubs and top predators that hunt in packs. While they can sometimes be found in tropical waters, they generally prefer colder waters. This makes tropical waters safer for baleen whale pups.
Calves breastfeed for 4 to 11 months and stay close to their mothers at all times. Nursing calves grow quickly from mother’s milk, which has a fat content of almost 50%. During the feeding period, the calves learn from their mother many important rules of behavior, such as how to feed. Calves are usually weaned in the first summer spent in feeding grounds and return to tropical waters alone the following winter.
How far do baleen whales migrate?
Most baleen whale species travel between 1,800 and 3,000 miles one way. Southern humpback whale populations leave their Antarctic feeding areas every January and spend three months traveling 3,000 miles to their breeding grounds in northern Australian waters.
However, some species actually travel much shorter distances. Seichalot feeding grounds are not so close to the poles, so they do not migrate that far every year. Bryde’s whales prefer warmer waters of 16 degrees Celsius or more (61 degrees Fahrenheit), so their migration is shorter as they feed in temperate waters and then travel to the equator to breed. However, some populations of Bryde’s whales are classified as “permanent” whales. This is because they do not migrate at all and remain in the same place all year round.
Gray whale migration: the longest migration of any animal in the world!
Depending on the species and location, some of these migrations can be very long. The gray whale has the longest recorded migration of not only a whale, but any animal in the world. Gray whales have been reported to have traveled an incredible 14,000 miles from the Sea of Okhotsk to the Baja Peninsula.
Scientists recorded the migration of gray whales in 2015 using GPS and were surprised that a 9-year-old gray whale named Varvara traveled 13,887 miles! Surprisingly, gray whales travel nearly 14,000 miles, but these are just three calving lagoons where they give birth to their young. All are in Baja California.
Migration of blue whales
The migration patterns of blue whales are much more diverse than those of gray whales, and scientists are still looking for many answers to the question of their migration. For example, the breeding sites of blue whales in the Southern Hemisphere are still unknown, but they are believed to be in deep ocean depths across the tropical regions of the Indian, Atlantic and Pacific Oceans. In the Northern Hemisphere, blue whales migrate between their favorite breeding grounds such as Costa Rica and off the coast of California and in northern waters where they go to gorge themselves on their abundant food.
Because blue whales have much less specific migration patterns, some of them may even remain year-round in certain geographic regions.
Humpback whale migration
Humpback whales have much more diverse spawning grounds than gray whales. One of the popular breeding grounds is Hawaii, where about 10,000 humpback whales migrate each winter when they can be seen between November and May. Cabo San Lucas is another popular spot for humpback whale watching in winter, as humpback whales pass by, heading for breeding grounds in the Sea of Cortez and along the Mexican coast. Other popular breeding grounds for humpbacks are off the coast of Brazil, equatorial Africa on both coasts, along Japan, Australian Queensland and the west coast.
Although most humpbacks migrate, the Arabian marine humpback is considered an exception. This poorly studied group of humpbacks is isolated and, apparently, does not follow the migration patterns observed in other humpbacks.
Are baleen whales endangered?
Unfortunately, several species of baleen whales are under threat, with blue, right, humpback and seismic whales classified as endangered. Many of these populations were almost completely wiped out during commercial whaling operations. However, while large-scale whaling is now a thing of the past, many dangers still exist for these magnificent whales.
Collisions with ships are a major factor for some species, especially blue whales, which often cannot get out of the way fast enough due to their sheer size. The increase in the speed of modern ships on already congested sea lanes also increases this risk. In addition to being hit by ships, baleen whales face threats of pollution, disease, and fishing gear.
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