Surprising behavior in one of the world's least studied mammals

Some animals live in such remote and inaccessible areas of the Earth that it is almost impossible to study them in their natural habitats. Among the beaked whales that have been found are 24 species so far: They live far from land and in deep ocean waters, where they search for food at depths of up to 500 meters and more.

The record holder for the deepest mammal dive is the Cuvier's beaked whale, which was measured in 2014 to dive at least 2,992 metres. The beaked whale also holds the mammal record for the longest dive; 222 minutes.

Now, the world is getting a surprising new insight into the world of distant beaked whales through a scientific study of a group of Byrd's beaked whales. The population was unexpectedly found closer to the coast and in shallower water than previously observed.

The study was led by whale biologists Olga Filatova and Ivan Fedotin from the University of Southern Denmark/Fjord & Bilt. Published in the magazine Animal behavior.

Filatova and Fedotin have many years of whale studies in the North Pacific, and during an expedition to the Commander Islands in 2008, they first saw a pod of Byrd's beaked whales near the coast.

“We were there to look for killer whales and humpback whales, so we just noticed that we saw a group of Byrd's beaked whales and didn't do much about it. But we also saw them in the following years, and five years later we suspected it was a sedentary community that visited the same area repeatedly.”

“We saw them every year until 2020 when the coronavirus prevented us from returning to the Commander Islands,” explains Olga Filatova, a whale expert and postdoctoral researcher at the Department of Biology and the SDU Climate Group at the University of Southern Denmark.

The groups of Baird's beaked whales studied were close to the coast, at a distance of four kilometers from land, and were observed in shallow waters, at a depth of less than 300 metres.

“It's uncharacteristic for this species,” says Olga Filatova, who also points out that this group has likely adapted to this specific habitat, thus deviating from the prevailing perception that all beaked whales wander far out to sea and into deeper waters.

“This means that you cannot expect all individuals within a species to behave in the same way. This makes it difficult to plan for species protection – in this case, for example, you cannot plan based on the assumption that beaked whales only live in remote places,” she says. Olga Filatova: “In the deep sea. We have shown that they can also live in shallow and coastal waters. “There may be other different habitats that we are not yet aware of.”

There are many examples of individuals of the same whale species not behaving in the same way. In the world of whales, it is common to find groups of the same species living in different places, eating different prey, communicating differently, and not liking to mix with other species in other groups.

Some killer whale groups hunt only marine mammals such as seals and porpoises, others hunt only herring. Some humpback whales migrate between the tropics and the Arctic; Others reside in certain areas. Some groups of sperm whales develop their own dialects for internal communication and do not like to communicate with others outside the group.

According to Olga Filatova, social learning plays a role when groups develop preferences, for example, for habitats and prey.

There are many forms of social learning in the animal world. Imitation is the most complex form; The animal sees what others do and understands the motive and logic behind it. Then there is “local reinforcement,” where an animal sees another animal heading to a certain place, follows it, and learns that the place has value. This has been observed in many animals, including fish.

Olga Filatova believes that the population of Baird's beaked whales in the Commander Islands learn through “local improvement.” They see that some of their peers go to the shallow waters near the coast, follow it, and discover that it is a good place, perhaps because there are a lot of fish.

“This has become a cultural tradition, and this is the first time a cultural tradition has been observed among beaked whales,” she says.

Other examples of cultural traditions in whales include when they develop specific hunting traditions: some slap their tails to stun fish, some generate waves to wash seals off ice floes, and some chase fish onto the beach.

Researchers observed a total of 186 individuals of the beaked whale species in the Commander Islands from 2008 to 2019. Of these, 107 were observed only once and were therefore assessed as transient whales. 79 individuals were monitored for more than 1 year and were assessed as residents.

61 passing whales were seen interacting with residents, seven of which were seen in shallow waters.

“The transients are not as aware of the local conditions as the population, and therefore, they usually forage at depths natural to their species. But we actually observed some transients in the shallow area. These were individuals who had a form of socialization with the population,” says Olga Filatova. . Through this contact, they should learn about shallow water and its advantages.”

It is unclear how many Byrd's beaked whales there are in the world.