An international team of scientists has observed the behavior of several groups of males whales of Globicephala species known as pilot whales and long-finned pilot whales, in the Strait of Gibraltar and Cape Breton (Canada). Their results indicate that these whales swim in synchronous when they recognize an external threat.
In the Strait of Gibraltar inhabit about 300 pilot whales. These whales are present throughout the year in the waters of the Mediterranean Sea and the Atlantic Ocean, but little is known about their social structure.
A study led by the University of Aberdeen (UK) in collaboration with the Doñana Biological Station (CSIC) and the group Conservation, Information and Research on Cetaceans (CIRCE), has analyzed the patterns of association between individuals within this whale community, to provide a long-term vision of their social system.
“The important thing is that we compared two different populations, one that lives in the Strait and is exposed to predators, which in this case are the ships, and the other with an ecotype where there is no presence of so many ships, in the Cape Breton in Canada . Pilot whales are social species and we were interested to see, for example, how to document learning from mothers to offspring. What we see is that they are synchronized to danger, “explains Renaud de Stephanis, a researcher at the Biological Station of Doñana and coauthor of the study published in the journal Behavioural Processes.
The scientists collected samples from 1999 to 2006, 23.004 kilometers of the Strait of Gibraltar, and took 4887 pictures of the dorsal fins of whales for comparison with Canada.
“Synchronicity is complete here and there. By having maritime traffic, or when the whale watches the boats nearby, there is a joint reaction of the group to external stimulation. When we arrived at the watching area they were swimming at their normal rhythm but after 10 or 15 minutes near to them, the mothers and their young began to swim in a synchronised manner in alert position. This is a sign of affiliation to the group,” adds the expert.
According to the researchers, these whales also have a social structure made up of permanent partners, i.e. remain for life time together and do not exchange individuals among the different groups as, for example, with bottle-nose dolphins.
Other data provided by this study is that the presence of boats also disturbs their behavior at the time of the dive. “So, at the beginning of the observation, usually long enough on the surface, and as we continue more time with them, increases the immersion time. It is a change of behavior that may affect their energy, since they will have to spend more to protect themselves and their children, limiting more time to hunt and thus to properly feed their young, “he concludes.