Traveling back and forth from the polar regions of the world, where big weather and food abounds, to tropical climates with gentle breezes and calm waters, humpback whales lead a nomadic lifestyle that many humans would envy.
However far their travels seem to take the whales, these impressive creatures live a very regular and cyclic life. How the cycle continues is due to motivations that prompt the whales to travel huge distances every year. Humpbacks manage to navigate thousands of miles between destinations, and their behaviors observed at each location indicate an animal completely adapted to life in the ocean.
At the end of the summer months, humpback whales begin their journey towards the equator. The algae bloom in the nutrient-rich waters of the polar regions that sparked an incredible growth in plankton is over, unraveling the base of the food chain, and ending the abundance of food for the whales.
Harsh weather will begin soon. While adult humpbacks would not be overly troubled by monster storms and washing-machine-waves, a newborn calf with weak muscles would struggle to remain with its mother, trying to time its breathing precisely between waves.
A percentage of the females heading back to the tropics are pregnant and due within a few months, and many of the other females will be ready to mate soon. Like many mammals, mating requires a significant amount of interaction between adult humpbacks. These interactions would be largely impossible in high sea conditions and at the very least, not very romantic.
Perhaps most important, the whales are heading to locations that have far less predators in waters that are considerably less deep. To a mother and her newborn calf, the safety of shallow, crystal-clear water from predators that may rise from the deep (specifically orcas or “killer whales”) are a top priority, and sightings of orcas in tropical waters are rare.
The migration to warmer waters takes about six-eight weeks. Humpbacks tend to be solitary travelers, sometimes seen in pairs, but not usually for long. The only exception to this are mother and calf, and then only as they return from the tropical birth place. A yearling is almost never seen in the company of its mother.
Biologists aren’t sure how the whales navigate such a long journey. No one underestimates the possibility of long memories in these whales, so one common theory is recognition of key coastal landmarks on the ocean floor. Other theories relate to the supreme eyesight of whales, both in and out of water, and that star navigation might be possible. Some suggest there may be a magnetic substance in their brain called “magnetite” that allow them to use the earth’s magnetic fields for guidance.
However they manage it, they all know where they’re going. The many miles traveled seem not to present a problem for the whales. Sometimes arriving at their breeding grounds is not always the final destination. For many of the adults, over the next few months they will continue to wander from one breeding area to the next, all within the same general latitudes, but adding considerable miles to an already epic journey. Humpbacks that frequent Hawai’i during the winter months might also be seen in Mexico or in Japan during the same season.
One unique behavior observed during the humpback mating season is their song. Humpback whales are the only whales that sing, and the males collectively create a song that is used only during the breeding months. Thought to attract females, the song is made up of distinct units, phrases and themes. Several themes together are repeated in a precise order, sometimes sung for hours by one individual. Constantly evolving as the weeks of the mating season continue, a new song emerges and is stored away in memory to begin the singing ritual the following year.
Utilizing sound frequencies in the ocean for communication is crucial to the survival of humpbacks. Sound waves travel five times faster under water, and whales have learned how to maximize the distance they can send sound. Aside from singing, these giant creatures will also breach, tail slap and pectoral slap the water to convey meaning with sound that is heard from miles away. As the fifth largest whale in the world, averaging in length around 45 feet and roughly 40 tons, humpbacks don’t appear especially built for the amount of splashing, jumping and excitable energy they display while breeding. Barrel-rolling, tail throwing, bubble blowing and high bursts of energy are also seen as males compete for females.
Returning back to colder waters after a successful mating season, the late spring and early summer months mark the start of a new algae bloom in polar regions. The humpbacks arrive just in time to break their long fast and start their feast on the abundant plankton that results.
Different from their behavior during breeding, the adults now work together in loose-knit teams to corral prey and create feeding circles. Since no food is available to them in the tropics, adult whales need about one ton of food a day to replenish the body fat lost during the migration. Typically, adults lose roughly one third of their total weight, and working in teams when feeding ensures they put on pounds faster.
Adapting to the ebb and flow of food supplies, whales use their blubber layer to sustain them during months of fasting. The blubber also stores water supplied from the massive quantities of food eaten, giving humpbacks sufficient fresh water to survive in a world of salt.
Humpbacks have proven their ability to survive within the cycles of the ocean, and do so with great success. Their regular migratory lifestyle motivated by food and safe waters, their use of navigational techniques still not fully understood, and behaviors that show advanced communication and adaptation skills together create an existence where humpbacks find harmony with their continuous ocean journey.
