Everyone has seen it in nature documentaries: a beautiful humpback whale lifting its enormous body all the way out of the water, followed by a gigantic splash. A jump - or, as we call it in the whale-world, a breach - is when a whale leaves the water head first to lift at least part of its body out of the water. Everyone who comes on a whale-watching tour hopes to see a breach - after all, it is undeniably impressive to see such a large animal use so much power to jump out of the water. But humpback whales also display many other surface activities that are exciting to see. The most frequent behaviours that we see - besides breaching - are pectoral slaps, tail slaps and rolling. In this post we explain what these behaviours might mean for the whales, and we also present some statistics to show how often they occur.
Humpback whale breaching - Photo by Rebecca Roberts
Why do they do it?
Although we wish we would see whales breaching all the time, it costs a lot of energy for a humpback to lift its full body out of the water. A 40,000-kg whale can use the same power as 25 draft horses use that pull 4,000kg each. In human terms, that may be approximately the same energy as a person expends during a marathon. It's therefore understandable that they display it sparsely. But with such a high energetic cost, why do whales breach at all? And what are the functions of slapping their pectoral fins and tails? There are multiple theories that might explain all of those behaviours:
The impact of the whales' bodyparts on the water might get rid of whale lice and barnacles that have comfortably installed themselves on the whales' skin.
A jump or slap might shock the fish around the 'landing site', making it easier for the whales to gobble up their prey.
The sound of a multi-ton whale crashing onto the water or slapping its tail or pectoral fin can travel very far. Those behaviours may therefore be a means of communication to other individuals, other species, or sometimes even to us.
We often see that when whales are socialising in a pair or trio, they display surface behaviours. It might therefore be a form of play or relaxation for the whales. Rolling, which is a very calm behaviour where the whale is laying on its back at the water's surface, is almost always an indication that the individual is relaxed.
When is the best time to see surface activity?
Although it is impossible to predict when and where and what is going to happen on whale watching tours, last year, we observed the highest proportion of surface activity during the early summer. Proportionally, the humpback whales were also more active during the evening tours than earlier during the day. Breaching was the most common behaviour, as it was seen in 12% of all tours! If you come on a whale-watching tour with us, there is a 1 in 10 chance that you might at least see one breach.
Tours with humpback whale surface activities per month in 2022
Humpback whale surface activities per tour at different times of day in 2022
Humpback whale associations and activity
Humpback whales are quite social animals, and they frequently occur in pairs or trios. Sometimes we even observe multi-species associations, particularly when white-beaked dolphins seek the company of one or multiple humpback whales. When we analysed our data, we observed that humpbacks are more likely to display surface activity during such intra- and interspecific associations, supporting the theory that these behaviours are important for social interactions.
Surface activity during humpback whale sightings in 2022 with one or multiple individuals.
Surface activity during humpback whale sightings in 2022 with and without dolphins.
We are still trying to understand what motivates humpback whales to perform such energetic displays in their feeding grounds here around Iceland. Luckily, we are seeing lots of breaches and other surface-activities lately. While we are figuring out why they are happening, we are more than happy to get to observe these impressive behaviours during our tours at Elding!
Humpback whale pectoral slapping - Photo by Rob Hyman
By Eline van Aalderink