by Rob Nawojchik The humpback whale is perhaps the favorite species of many whalewatchers. Humpbacks are well known for their diverse repertoire of dramatic behaviors, from fluking and breaching to flipper slapping and lob-tailing. Certainly, other species of whales exhibit these behaviors at times, but humpbacks seem to be particularly demonstrative when they’re showing off. Humpbacks seem to be oblivious to our presence and will carry on with their high-energy behaviors even when close by. At times, they seem curious and will approach or circle the Searcher as we drift alongside. (This is in contrast to a shy and elusive species such as the Bryde’s whale, which rarely affords us a close-up look.) There are several places around the world where humpback whales congregate during mating season. One of these places is the Gorda Banks, off the southern end of the Baja peninsula. During our 12-day Natural History Tours, one of our days is devoted to watching humpbacks on the Gorda Banks. We can (and do) see humpbacks at any point in our trip, both on the Pacific side of the peninsula and in the Gulf of California, but by far the greatest concentration and numbers of humpbacks are in the Gorda Banks region. Although we can’t see the Gorda Banks from the surface, the humpbacks apparently use the underwater feature as a focal point of their activities. This association with underwater geological features is typical for humpbacks and other species of whales. For example, western North Atlantic humpbacks (another population I’ve observed) congregate around Silver Bank and Navidad Bank off the Dominican Republic during breeding season, and around Stellwagen Bank off New England during the summer feeding season. In addition to their spectacular behavioral repertoire, another aspect of humpback whales that makes them fan favorites is that humpbacks are probably the easiest large whale species to identify. Once you’ve seen a humpback whale, you are unlikely to confuse it with anything else. Size and shape of blow: As always, keep in mind that the appearance of a whale’s blow is highly variable among individuals and is affected by the wind. For the humpback, the blow is usually described as “bushy,” reaching heights of about 10 feet or so. As we discussed in prior blogs, the blue whale often has a taller blow, the gray whale’s blow can appear heart-shaped of V-shaped, and the sperm whale’s blow is at a 45-degree angle (i.e., not straight up). Size of animal: Humpback whales reach about 50 feet (16m) in length. Among the other baleen whale species in Baja, blue and fin whales can get larger, gray and Bryde’s whales are about the same size, and minke whales are smaller. Color: Humpback whales are mostly black in color, with areas of white on the flippers and abdomen. The underside of the tail flukes ranges from all black to all white (more on that later). The black body color is in contrast to the mottled blue of blue whales, the blotchy gray of gray whales, and the slate gray of fin whales. Dorsal fin: Humpback whales have a dorsal fin, but its appearance is different from other whales. Humpbacks have a step-like base that forms the foundation of the upper more-typically-shaped portion of the dorsal fin. This overall shape may be the origin of the name “humpback.” Humpback whales arch their entire back quite dramatically when diving, and that behavior may also contribute to the name “humpback.” There is individual variation in the shape of the dorsal fin in humpback whales. Tail flukes: Humpback whales often show their tail flukes when diving. As mentioned earlier, the color pattern on the underside of the flukes is highly variable and individual-specific. The behavior of showing the flukes, coupled with the flukes’ high variability, makes fluke patterns a perfect characteristic to use for individual identification. Since the early 1970s, marine mammalogists have photographed the flukes of humpback whales and compiled catalogs of thousands of individual whales. By photographing and identifying individuals, many behavioral and ecological questions can be answered. I’ve been photographing the flukes of humpbacks during 10-years’ worth of Searcher Natural History Tours to Baja and have over 250 individual whales in my catalog. We’ll talk more about that in a subsequent blog. One last feature about the tail flukes: the trailing edge of the flukes often has a serrated appearance, in contrast to the more-smooth trailing edge in most other species. Species-specific traits: Humpback whales have several anatomical features that distinguish them from other whale species. We’ve already discussed the uniquely-shaped dorsal fin. Another unique character is the extremely long pectoral flippers. The flippers of humpbacks are one-third the body length, much longer than what we see with any other cetacean species. Thus, a 45-foot humpback would have 15-foot flippers! Yet another distinctive feature of humpbacks is the presence of a series of bumps on the head. These bumps, sometimes called “tubercles,” are over-sized hair follicles and in fact do contain a tiny hair in the middle. The function of these hairs is still speculative, but may be sensory. Regardless, the presence of these tubercles on the head of a whale is diagnostic for the humpback. All of the other whale species we see have a smoother head and lack large tubercles. Behavior: As mentioned, humpback whales exhibit a variety of high-energy out-of-water behaviors that are spectacular to witness. A “breach” is when the whale jumps out of the water. Sometimes the whale will breach just once, while other times a whale may breach repeatedly. Single breachers are hard to photograph as you never know where and when they will breach. With repeat breachers, you can sometimes anticipate the next breach. Although a few other species of cetaceans have been seen to smack their pectoral flippers on the water, this behavior is best exemplified with humpbacks, given the humpback’s giant pectoral flippers and the particular enthusiasm with which they perform this behavior. Referred to as both “pec-slapping” and “flipper flapping,” this behavior can be seen (and heard!) from quite a distance. The “lob-tail” is yet another high-energy behavior best seen in humpbacks. The whale is oriented vertically in the water, with the tail and caudal peduncle (the base of the tail) raised high out of the water. The tail is then smacked aggressively against the water, created a big splash and a loud sound. As with the breach and pec-slap, this behavior most likely has some communication value. We don’t have space today to discuss exactly what is being communicated, except to say this: for me, the first step when analyzing behavior is to determine the CONTEXT. Who is displaying the behavior? (calf? adult male? etc.) Where are they? (breeding grounds?) Who else is around? (other males? receptive females? etc.). Another behavior worth mentioning is one that you won’t see but will hear. Humpbacks are famous for their songs, usually produced by males on their breeding grounds. Aboard Searcher we have a hydrophone that we sometimes turn on while we’re drifting at the Gorda Banks. If the whales are singing and they’re close enough we can pick up their songs, which Captain Art then broadcasts on the Searcher’s speaker system. Superlatives always come to mind while watching cetaceans of any species. If there were a cetacean awards show, the humpback whale would get my vote for “Easiest to Identify” and “Most Entertaining.”
