Humpback Whales - Migration and Song
Humpback whale is a species of baleen whale. They can weigh 40 tons and be 50 feet long. To get an idea of how long they are... If you line up six of them from head to tail, they would span the length of a football field. If you don't watch football and/or not familiar with how long a football field is, think for three sedans parked bumper to bumper, that is how long one whale is. But they are much heavier than three sedans. Think 24 sedans; that's how heavy they are.
Humpback whales population had been as low as few thousand worldwide before an international ban on their killing went into effect in the 1960s. Now their population has rebounded and is estimated at 10,000 or more in the North Pacific. Their lifespan is around 40 years.
Many of them like to be near Hawaii during the winter months of November to May. This is where they mate and give birth. Females give birth every two to three years. Each pregnancy lasts 11 months. After birth, the infant is nursed and cared for by the mother for a year.
BBC video of swimming with whale
Humpback Whale Migration
After their stay in Hawaii, the humpback whales (and with their calve if they have) will migrate north to their feeding grounds in the polar waters of Alaska.
The journey is about 3000 miles long and baby calf can get tired. In the BBC Documentary Nature's Great Events, they show a mother humpback with her calf making the journey. You see the mother supporting the calf in its swim when it becomes tired. In the United States, the British documentary was shown under the alternative title Nature's Most Amazing Events, which is now available on DVD.
Why do they make such a long journey? The warm waters of Hawaii is ideal for giving birth. If you were a whale calf, wouldn't you rather be born into the warm weather of Hawaii rather than the icy polar waters? But the icy polar water is where they can get an abundance of food in the summertime. So they go north to feed.
When they arrive there, they have to eat a lot during their summer feeding season up north. Because they will have to live off their fat reserve when they go back to Hawaii in the winter. They eat about 2000 pounds of food each day during the feeding season. They doing this by gulping large schools of crustaceans, krill, small fish, and plankton. When they close their mouths to expel the water, the food is filtered using their baleen plates.
When they are inclined, the humpback whale can also perform an unique group hunting technique known as bubble-netting.
In the BBC documentary, you see underwater footage where a humpback whale gulp down a large bait ball in one gulp. You also see them doing some bubble-netting.
The humpback whale song is a mystery. Only the male sings. The song is one of the most elaborate and longest known in the animal kingdom. It can be 10 to 20 minutes long.
Surprisingly, it does not seem to attract females. Instead it attracts other non-singing males. The two males would swim for a while without aggression. All humpback within a region, say North Pacific, will sign the same song. The songs may change over time though the years. People such as Jim Darling has been trying to figure out the whale song for 25 years.
DVD: Nature's Most Amazing Events
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