Last week I was floating under gray skies and windless conditions on a whale-watching boat outside of Hoonah, Alaska. We drifted with engines off while Humpback Whales (Megaptera novaeangliae) fed around a rocky reef a hundred yards that was exposed by a shrinking tide. The distinct kee-kee-kee of hundreds of marbled murrelets, (Brachyramphus marmoratus, small pelagic birds) rang out around us and the bellow of sea lions droned from a distance green channel buoy. Towards that buoy an enormous nose broke through the surface and in a fraction of a second a mature Humpback Whale hung in the air with only the tips of its tail in the water. Its re-entry sent water far into the air with a crash. On its second breach I was ready and captured a series of shots as it arched into the water. My heart was racing as I soaked in what had just happened! Ultimately its leap from the water set my mind turning on why a whale would try to fly at all.
Mature Humpback Whales are gigantic creatures weighing between 45-50 tons (NOAA) and reaching up to 45 feet. I think Whitehead (1985) has it right when he states, “A Whale’s leap from the water is almost certainly the most powerful single action performed by any animal.” He found that a 12-m long adult humpback must travel at about 17 knots (3 times their normal cruising speed) to break the surface and expose at least 70% of their body. The energy required to thrust their entire body comes at an expense of energy, and begs to question about what they gain from it. It is possible whales breach to communicate with others, to act aggressively towards another whale, to show strength, or to “play” (Whitehead 1985).
A lot of research on aerial behavior has tried to associate breaching with group dynamics. These studies have yielded interesting correlations. Whales breach more often in groups (Whitehead 1985). They were more likely to breach within 10km of another whale. Humpback whales surface activity (including multiple behaviors above surface) increases with group size and also occurred more with underwater vocalizations (Silber 1986). There also seems to behaviors which foreshadow breaching. For instance, breaching often comes after a tail lob. A tail lob is another visual and audio spectacle where the whale slaps its tail against the water. Since breaching occurs more often in groups, these lends to the notion that it is a form of communication.
For some researchers, time spent on water results in findings that have little explanation. For instance, whales may breach more as wind speed rises (Whitehead 1985). Although support for why that would be is nearly impossible to determine, it has been shown that surface slaps can carry for several kilometers and the amount of sound created changes depending on what angle the whale strikes the water (Payne and McVay 1971, Deakos 2002 citing Watkins 1981). The distance that a breach can be heard is unknown, but it certainly surpasses the visual extent lending to the hypothesis that it is a form of communication, however, what message it conveys is unknown.
By listening to whale vocalizations (for which humbacks are famous) that occur leading up to breaches, researchers found there is a relationship between the amount of vocalizations and breaches. Male to male interaction and above water behavior were often correlated with increased vocalization between males (Silber 1986). It is likely these vocalizations are aggressive and that males are plying for position or to mate with a female. The subsequent breach is probably an “exclamation” (Whitehead 1985) on the underwater vocalization rather than an attempt to harm the other whale during the breach. Certainly it would demonstrate to a female the prowess and strength of the male (Whitehead 1985).
Insight into breaching behavior may be gained from researching other percussive behaviors. Deakos (2002) found that pectoral slapping varies with age class, sex, and social position. Females were likely to slap pectoral fins on the surface to indicate readiness to mate, while males often did it to compete with other males without full-on combat. Pectoral slapping was shown to be frequent in young whales and is likely an important piece of their development (I was fortunate to see a calf breaching last year). However, pectoral slapping and frequent breaches from young and feisty individuals taper off as the whales mature and get older (Whitehead 1985). This likely means it not a form of play for older animals. From these findings in pectoral displays we likely assume that a breach from male, female or young calf means separate things.
My review of the science and literature surrounding whale behavior is stumped by the same issue that plagues the field : the true question of “why” a whale breaches is illusive because “what” they are trying to convey is likely different for each whale. Much like the way that we clap our hands different at sporting events, golf tournaments, at a wedding, or after a concert, whales likely use the clap of the water to communicate different feelings. Answers are relegated to vaguery due to the inherent difficulty of researching an underwater animal. I can only conclude that whales breach to communicate. It seems most plausible that humpback whales and other species breach to add emphasis to a message or to get a point across.
Deakos. (2002). Humpback Whale (Megaptera Novaengliae) Commication : The context and possible functions of pec-slapping behavior on the Hawai’ian wintering grounds. Thesis.
Payne, R. S., & McVay, S. (1971). Songs of humpback whales. Science, 173, 585-597
Silber, G. 1986. “The relationship of social vocalizations to surface behavior and aggression in the Hawaiian humpback whale (Megaptera novaeangliae)”. Canadian Journal of Zoology. 64(10): 2075-2080
Watkins, William A. (1981). “Activities and underwater sounds of fin whales [Balaenoptera physalus].” Scientific Reports of the Whales Research Institute (Japan).
Whitehead, H. 1985. “Why Whales Leap”. Scientific American.