Socialising in feeding grounds?
The humpback whales we see in Faxaflói are generally solitary: they come here to feed, and socialising is not very high on their agenda - at least, that is what researchers have always thought. Recent evidence, for example from the many encounters with pairs of humpback whales during this summer on our whale watching tours, suggests that humpback whales are not such “loners” after all. We have even seen three whales staying close together in the bay over the last two weeks! As so little is known about the social dynamics of baleen whales in Icelandic waters, we hope to understand more by analysing who these whales are through photos and what they are doing through behavioural data collection. For now, we can only hypothesise, but here is what we know so far:
On October 14th 2021, we encountered two whales feeding in the same area. A third whale had joined them when we next saw them on October 22nd . Since then, we have seen the trio of whales regularly on our tours. Of course, we never know what the whales do when we are not watching them: they may have split up sometimes and joined together, or they may have stayed together the whole time.
With our catalogue, we can match individuals based on the unique pattern on their flukes and we can track when and where we saw which humpback whale. As far as we know, the humpback whales have not been encountered together before, but we recognise one of the individuals as “Homer Simpson”: a whale that we have been seeing in Faxaflói since the end of this summer.
Photos of the whales’ dorsal fins and tail fins allows us to recognise each individual and keep track of their movements and social associations.
What are they doing together?
The three whales have been a treat for our whale-watching passengers, showing very social behaviours such as rolling, lobtailing, pectoral slaps, and coming exceptionally close to our boats. We have also observed the whales feeding and resting together. Whereas humpback whales’ feeding strategies in other parts of the world sometimes involve the teamwork of many individuals, the whales in Faxaflói mostly lunge feed by themselves. If the whales aren’t together for cooperative hunting purposes, could their intentions be purely social? Are they “friends” or might there even be sexual motives?
Humpback whales often hunt cooperatively, for example by bubblenet feeding. In Faxaflói, humpback whales mostly obtain their prey by lunge feeding alone.
Is it possible that humpback whales mate in feeding grounds?
The common conception until recently was that humpback whales don’t mate in Icelandic waters: they come here to feed in the summer, and in the winter most whales migrate to warmer waters to breed. However, evidence is accumulating that whales may be getting more action in Iceland than we thought. The encounters of pairs and even trios of humpback whales suggest that some individuals do socialise in Faxaflói (although the extent of these social relationships is not known yet). Another hint is that some humpback whales stay around Icelandic waters the whole winter. Are they only staying here to gain extra winter weight, or do they also attempt to mate with other overwinterers? The final, and most convincing evidence comes from acoustic recordings of humpback whale songs in the winter months (corresponding with their mating season). The songs of male humpback whales are believed to attract mates, so the presence of these mating songs in Icelandic waters might point to the occurrence (or at least males’ attempts) of breeding in these waters.
There is clearly a lot to find out about whales´ social dynamics in the waters of Faxaflói and the rest of Iceland. One of our research aims is to go through our photos of the humpback whale pairs and trios that we have encountered this year and in previous years to gain a better understanding of the associations and social behaviours in their feeding grounds.
By Eline van Aalderink