Migratory animals take an annual journey between two places, usually at the same time every year. Humpbacks live in cold oceans most of the year, and warm oceans for part of the year, traveling between their two homes annually. Theirs is one of the most spectacular migrations on the planet. Humpbacks migrate farther than any other mammal. They travel around 3,000 miles each way, every year. Humans do not yet understand how they navigate to find their destination. They fast (the whale does not eat) during their trip down and back, and the duration of their stay in the mating and calving grounds. Although the average stay in the mating and calving grounds is four to six weeks, a male Humpback was seen here for three whole months! Another male was seen in the Hawaii breeding grounds, then in Mexico during the same season. Also, whales do not always return to their same breeding grounds season to season. Some Humpbacks migrate who are neither mating nor having calves. All these details about their migration, which we don't understand, remind us that we really don't know that much about these whales. Since we can really only observe them when they're at or near the water surface, there are many things that remain a mystery.

Annual Migration

Humpbacks migrate annually to their mating and calving grounds in tropical or subtropical locations. The exception to this is the population in the Indian Ocean and some whales in Costa Rica, who do not migrate. Rarely, there are some whales who stay behind in their feeding grounds, but scientists do not understand who they are or why they stay behind. (Researchers much prefer studying whales in warm, tropical climes to studying whales in freezing cold oceans in the dead of winter, so it may be awhile before we really know who is staying behind and why.) Early each season, the whales start showing up in their mating and calving grounds as a harbinger of the excitement to come.

How Long It Takes

This approximately 3,000 to 3,500 mile migration takes them about 30 to 35 days each way, so they are traveling about 100 miles per day. They travel an average of three to five miles an hour for the duration of their journey. This is a lot slower than taking a plane across the Pacific, but they get to see more sea creatures on their trip, and whales would have a hard time fitting into airplanes anyway.

How Far They Go

Humpbacks migrate longer distances than any other mammal. The longest recorded migration a Humpback undertook was a whale tracked from Antarctica, across the equator to Costa Rica, 5,157 miles. Usually, Humpbacks migrate about 3,000 miles North or South. A very few, motivated animals have crossed the equator (to be recognized as a Son of Neptune?) but usually Humpbacks do not cross the equator, instead migrating to destinations located on the planet at 22 degrees North or South in the Northern and Southern Hemispheres.

How Do They Find Their Way?

We don’t know how whales navigate to find their way to their migratory destinations. It’s one of the big mysteries of the whales. Current theories include:

• They may be celestially navigating, using the stars to visually locate their destination
• They may be using deep ocean trenches or underwater landmarks to visually locate the way to their destination
• The small amount of magnetite, a magnetic element, is found in their brains and may allow them to align with the earth’s magnetic fields and polarity as if they were using an internal compass

Destinations

Whales from widespread feeding areas come together to concentrate in the mating and calving grounds. This probably gives whales a bigger selection of mates. Whales seen in the upper latitudes may be migrating, as opposed to having reached their migratory destination. Whales traveling on their migratory path are few and rarely seen, since they are just passing through the area. There are more whales in the migratory destination, as they concentrate here, coming from many feeding grounds to meet in the mating and calving grounds, for an average of four to six weeks.

Most whales return to the site they visited previously. Humpback calves tend to return to the mating grounds and feeding grounds that they traveled to with their moms, but whales occasionally visit different breeding grounds between seasons.

Scientists do not know too much about the few whales who stay behind in the feeding grounds. Most all of the whales leave the feeding grounds to migrate to the mating and calving grounds, even juvenile whales that are not sexually mature. The whales that stay behind may be females who are not pregnant or do not wish to mate. It is possible that older whales stay behind as well.

Why do you think whales would stay behind?

Humpbacks do not all migrate together at once. Despite the fact that whale season in the mating and calving grounds lasts about four months, each individual whale stays in their mating grounds for an average of four to six weeks. Because of this, there is a peak in the middle of the season when the most whales are in the mating and calving grounds. Some whales migrate early in the season, some migrate in the middle, and some whales migrate later. Humans can relate to the whale season by imagining a dinner party. There are a few people who come a little early, most people come during the middle of the party, and there are always a few who stay way too late, and it is the same for the whale’s breeding season. There’s always a few males hanging around in April wondering where all the girls went.

The largest concentration of whales in the mating and calving grounds happens in the middle two months of the mating season. This occurs in Hawaii from mid January to mid March and is the best time of the year to see the most whales. What do we mean by ‘best’? Much of whale watching is whale ‘waiting’. If you come any time between December 15th and April 15th, you’re almost guaranteed to see whales. However, what makes whale watching so amazing is surface activity! Breaching, tail slapping, whale fights… the behaviors that make your jaw drop. If you have more whales, you’re more likely to see exciting stuff and spend more time whale watching vs. whale waiting. So as you get closer to the peak of the season you just have better odds of seeing more surface activity, since there are so many more whales together

In contrast to time of year, there is no better time of day to go whale watching. There is no correlation between active whales and time of day or weather conditions. As proof, whale watch companies would charge more for a “better” whale watch if they could figure out when it was going to happen. Humpbacks are equally active through the night as they are during the daytime because of the way they sleep.

Whales stay in their mating and calving grounds for an average of four to six weeks, but it depends on who you are as to how long you stay:

• Moms with new calves will stay an average of four to six weeks
• Juveniles and yearlings will stay an average of four to five weeks
• Males looking to mate will stay up to eight weeks
• Females looking to mate and get pregnant will stay about a week, sometimes they may not even make it all the way down to the migratory destination. Females that do not have calves are thought to return to the feeding grounds as soon as they are pregnant, and that they “just know” when they are pregnant.

Male to Female Ratio in the Mating Grounds

Males stay longer in the mating grounds than the females do. This is especially true for females that aren’t pregnant, as they only stay about a week. So it appears that there are many more males than females. Scientists calculated that there are more than 2 males for every female present in the mating grounds, but in the feeding grounds the whole population is split evenly between males and females.

Since the whales aren’t feeding when they’re in their breeding grounds, leaving early might seem to indicate that this is further proof that females are smarter than males. Then again, it may just prove other things about the priorities of males.