New discoveries made through drone footage of gray whales feeding habits

Drone footage of a gray whale captured off the coast of Oregon over a seven-year period reveals new details about how the giant marine mammal finds and eats its food.

The findings, described in two studies published this summer, include that gray whales use different swimming techniques to gather food depending on their size and age, and that larger whales are able to swim more easily in the water. It includes a high chance of spitting out a “bubble explosion” to stay in place.

“Until this study, we thought all whales exhibited this behavior,” said Clara Byrd, lead author of both studies and a research scientist at Oregon State University's Marine Mammal Research Institute. said. “No one thought there was a pattern to who behaved in what way.”

Bird's research also found that whales use different predation techniques depending on the depth at which they forage and the habitat of their prey. Such information could inform future conservation efforts, she said, as it provides insight into the types of habitats that need to be protected to maintain whales' access to food.

“While we are not currently actively seeking to protect specific habitats, future concerns include the possibility that whales of different ages may not all be using the same habitats. “It's very important to know,” Bird said. “It will help us manage them in the future.”

Some gray whale populations are designated as an endangered species Under the Endangered Species Act. The entire species was once at risk of extinction due to commercial hunting. Gray whales were once common in the Northern Hemisphere, but are now only regularly seen in the North Pacific Ocean. As of 2016, just under 27,000 of them are estimated to be in the region. According to a 2020 report from the National Oceanic and Atmospheric Administration.

Whales eat amphipod crustaceans, such as small shrimp and earthworms. These creatures suck up water and sediment from the ocean floor where they live and use their whiskers to filter and consume food. Gray whales are usually observed alone or in small groups, but large groups can sometimes be seen on feeding and breeding grounds.

Bird and her team conducted a survey off the coast of Newport. During their seven-year voyage, the group used drones to track and record individual whales. They used identification markers such as scars, spots, and tail shapes to identify specific whales.

The first study that resulted from that research was Published in Animal Behavior magazine in Julyfocused on changes in whale foraging behavior depending on size and habitat.

The research team tracked 78 gray whales in a total of 160 sightings from 2016 to 2022. In drone footage, young, small whales were observed often swimming sideways or facing forward, opening and closing their mouths in an attempt to find and ingest food. . Older, larger whales, on the other hand, tended to dive and then stay in place with their heads down, in what scientists describe as a “handstand technique.”

As whales grow larger, the probability of such headstands increases, but the probability of forward swimming tactics decreases, the study found. Water depth and habitat type, including rocky, sandy, and coral reefs, also influenced the whales' approach.

Bird believes the switch in technique is due to the maturation of the whale's muscles and its level of strength and coordination.

Her team's second study was published Published in Ecology and Evolution In August, we explained how older, larger whales emit air through their blowholes to stay underwater as they forage.

These “bubble explosions” can reduce the whale's buoyancy and help it sink. Larger whales have a greater need for this because their lungs hold more air, contain more fat, and are easier to float.

The discovery was based on observations of 75 whales. On average, the bubble explosions occurred 27 seconds after the whale dove took off in search of food, and most were observed while the whales were doing a handstand. The older and larger the whale, the more likely such an explosion will occur.

“Combining size and individual-level behavior in this way is a really interesting part of this study,” Bird said.

Susan Parks, a biology professor at Syracuse University who has published research on whale eating habits but was not involved in the new study, said documenting the diversity among whale species is important for scientists. said that it helps avoid inaccurate generalizations.

“When working on conservation efforts and protecting endangered species, it's really important to understand that there can be large variations in behavior,” Parks said. “So you can't just stop at a single observation.”

The park also highlighted the potential drones have for collecting detailed data about whales.

“There is so much we don’t know about whale behavior,” she said, adding that the study “uses drone footage to essentially monitor whale behavior to help explain how whales make a living.” “It gave us a completely different perspective on the details of what's going on,” he added.