Of all the tropical animals that I have experienced, the humpback whales seem to be the most popular. Like most popular things, lots of information can be found about them, yet it seems that there are many more questions than answers. I have experienced humpback whales so often that I have my own a hypothesis that even contradicts the infamous David Attenborough. A statement like that proves that I am either missing some valuable information or it emphasizes how widely misunderstood these creatures still are.
I wrote in an earlier blog that the YouTube videos I produce are normally created when my friends and/or family visit. The GOPRO video below, was created in August 2018 after a group of friends asked me to impress them with something special. For me, almost everything about Drake Bay is special. However, on this occasion, a humpback whale day was the answer.
Drake Bay’s Humpback Families
Drake Bay has the enviable distinction of having the longest humpback whale season in the world, as we are visited by 2 distinct groups throughout the year. In general, humpbacks migrate to the poles to feed and then to equatorial locations to birth and breed. We host a northern hemisphere group, known as the California humpbacks, from early December to mid-May. And the southern hemisphere group, which is known as the Antarctic humpbacks, from mid-July until the end of December. During December, Drake Bay is the only breeding and birthing location to host members of 2 humpback groups at the same time.
The most obvious visual difference between the two groups is their pectoral fins. The California humpbacks have white only on the bottom of their pectoral fins, while the Antarctic have pectorals that are completely white. The only other visual difference that I am aware of, is their physical size. The southern hemisphere group members are larger and can exceed 18 meters (60 feet) in length and fifty tons. While their cousins in the north are rarely longer than 15 meters (50 feet) and usually less than 40 tons. (1) The Antarctic humpbacks are the largest group left on earth containing over 2,000 individuals. When the Antarctic group is active in Drake Bay, it is normal to experience between 15-20 humpbacks on any given day.
Humpback Whale Breaching Behaviors
Pregnant mothers are normally the first to arrive, and birthing occurs shortly afterwards. Because of this, transient killer whales often arrive at this time to take the opportunity to hunt the newborns, before the remaining humpback reinforcements enter the region. This obviously adds an element of excitement for whale watchers, however due to exhaustion from the long journey, the humpbacks are otherwise not very active at this time. Humpbacks are also less active during the month before migration, as they rest up for the long journey back to the poles.
The months between the first and last on the other hand, are filled with breaching and other distinctive surface behaviors that occur all day and even throughout the night. Humpback mothers normally keep their month or two month old calves very close to shore for protection. During their second month, the babies become very active. They perform the same types of breaching behaviors as adult males, which includes; pectoral slaps, tail slaps, head slaps or lunges, peduncle tossing and spy hopping. Humpbacks do not perform these surface behaviors while on migration routes nor while in feeding waters. With the possible exception of spy hopping, which is when the whale pokes it’s head vertically from the water, with no splash. This behavior is known to be for the purpose of navigation, by way of visually identifying landmarks.
Many have claimed that adult males perform these actions as a form of communication (the loud splashing can be heard from great distances). Or perhaps as a way to attract females, or a way intimidate other males. I have never heard or read anything that supports my belief, but my hypothesis is that adult males and babies do these things for exercise. These various surface activities seem like the perfect exercises to increase an individual’s ability to swim for long distances and at fast speeds. To me, it makes sense that babies need to build muscle mass to endure their first journey to the feeding grounds located at the poles.
It is my personal belief that the adult males are also exercising as part of their breeding rituals. When a female is coming into heat, males come from all around. Females are larger than males and thus they are able to swim faster and with more longevity. When a female is ready, she begins to swim and many males give chase. This is called a heat run. The males literally fight for the chance to breed by crashing into one another in the hope of dominating the race. In some instances, males are actually killed during the high-speed fight. In the end, the female will breed with the male that chases her for the longest time, resulting in the strongest genes being passed on. If males are willing to die for this opportunity, then exercising beforehand seems worth the effort. Especially when considering how many heat runs a male may participate in throughout a breeding season.
I’m not ready to call BBC yet, but I feel very confident that my hypothesis pertaining to the purpose of breaching is more logical than David Attenborough’s suggestion that it is a form of communication. Sir Attenborough has been recorded saying that the breaching may also be a form of attracting females or perhaps intimidating other males.
This species is known to possess language, and can create other sounds that travel much farther than the sounds they could make with a splash. It also makes no sense to me that they would make splashes as an attempt to attract a female when it’s understood that he must still fight and race for her regardless. As far as intimidating other males, I suppose that it would be intimidating if other males were able to perform more impressive exercises because it would logically lead to the presumption that those competitors would have the best chance of being the victors.
Whale Reproduction and Hybrids
Female humpbacks reach sexual maturity at age five, achieving full adult size a little later. Males reach sexual maturity around seven years of age. Females typically breed every two or three years. The gestation period is 11.5 months. The peak months for birth are January and February (northern hemisphere group); and July and August (southern hemisphere group). Females wait for one to two years before breeding again. Recent research on mitochondrial DNA reveals that groups living in proximity to each other may represent distinct breeding pools. Humpback whale births have rarely been observed. One birth witnessed off the coast of Madagascar, took just 4 minutes. Humpback whales have been occasionally known to hybridize with other rorquals, as there is a well-documented report of a humpback-blue whale hybrid in the South Pacific. Humpback whales also appear in mixed groups with other species, such as the blue, fin, minke, gray and sperm whales. (2)
The Famous Humpback Song
Both male and female humpback whales vocalize, but only males produce the long, loud, complex “song” for which the species is famous. The song lasts for 10 to 20 minutes, which is repeated for hours at a time. The California and the Antarctic humpbacks sing a different song from each other, but whales within groups have one song only. However, these songs are not static. Each population’s song is known to evolve over a period of several years, with small changes slowly adding up to more noticeable differences. (3)
Scientists are (as yet) unsure of the purpose of humpback whale songs. It has been observed that singing males are often approached by other males, frequently resulting in conflict. Singing may, therefore, be a challenge to other males. Some scientists have hypothesized the song may serve as an echolocation function. Humpback whales make other sounds to communicate, such as grunts, groans, snorts and barks. (4) They stop singing when they leave the breeding grounds, but continue with their evolving tune when they return. “They resume the song at the same point that they left off.” explains Mark Simmonds, director of science at the Whale and Dolphin Conservation Society. (5)
Study of Migrations
Because whale tail identification is a relatively new field in cetacean studies, we have only recently begun to understand the migrating habits of these amazing creatures. In 2007, Kristin Rasmussen from the Cascadia Research Collective in Olympia, Washington came up with some fascinating research related to our humpbacks. The study identified seven individuals wintering off the Pacific coast of Costa Rica, as having traveled from the Antarctic around 8,300 km (5,200 mi) away. Identified by their unique tail patterns, these animals had made the longest documented mammalian migration. Seven animals were photographed in both locations and a mother and calf pair were seen in Antarctic waters 161 days after they had been spotted in Costa Rica, having traveled 5,266 miles.
In all cases, the animals were choosing water temperatures of around 24-25C. The whales she studied off the coast of South America would have to continue beyond the equator to find water this warm. Ms Rasmussen believes that a high enough water temperature is crucial for them to breed. “It’s likely that being in warm water is somehow beneficial to the calf,” she said. (6)
Whale Watching in Drake Bay
During migration, humpbacks know where they are based on their visual recognition of shoreline landmarks. For this reason, the species is normally found within 20 miles of the coast, making them easy to spot even while relaxing on one of our many Drake Bay beaches. Adult males are normally father from shore, and rarely interested in humans. Calves on the other hand, are often very curious and it’s sometimes possible to swim from shore to meet them. Having said that, you increase your odds enormously by participating in a whale watching trip by boat.
During the month that my friends visited in 2018, the humpback whales were everywhere and very active. At this time of year, even Cano Island or Corcovado National Park tours often encounter humpback whales along the way. Tours like this however, observe the whales for a short time- continuing along to the tours primary objective. Dedicated whale watching tours have the unique opportunity to spend a comprehensive amount of time with the cetaceans encountered.
Another advantage is that there are some distinct humpback “hotspots” that are not en route to either Cano Island or Corcovado. On this particular day, we had the opportunity to visit a reef known as “Paraiso” (paradise). As you can see from the video below, I certainly met my goal of showing them something special and they told me that the experience surpassed their expectations.