Does that orca have a baby bump? Drones can tell from the air

Orcas, like humans, get baby bumps in the early months of pregnancy that grow larger as the pregnancy advances.

Researchers say they can now spot those underwater baby bumps from the air and keep better tabs on whales' maternal health.

The Northwest’s endangered orcas have been having a hard time reproducing.

The calves often die before their first birthday, with a shortage of salmon, toxically polluted mothers’ milk, and inbreeding thought to be key causes.

Pregnant orcas often have miscarriages, though how often is unclear.

Researchers with the nonprofit Ocean Wise in Victoria, British Columbia, say they can use drone photos to spot pregnant orcas by their body shape — even ones with just a baby bump.

“It's statistically different, the shape, even though you can't really see it with the eye,” said coauthor and aquatic ecologist Chloe Robinson.

“We start seeing that very subtle bump in sort of the mid-region, but the whales also gain a little bit of weight, so the shape around the head will change a little bit,” Robinson said. “Essentially, that sort of ratio between the length of the whale and the width of the whale will change.”

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Robinson and coauthor Brittany Visona-Kelly describe their method for quantifying the shape of an orca in the Jan. 25 issue of the journal Scientific Reports.

They used measurements derived from drone photos to determine whether an orca is newly pregnant, heavily pregnant, lactating, or not pregnant at all.

The researchers devised a protocol for identifying six “landmark” points on an orca’s body, from the nose to the notch of the tail fin, that a drone can photograph when a whale is swimming just beneath the surface.

“There hasn't been an existing method to look at those earlier stages of pregnancy, such as between the first month all the way through to the 10th or 11th month of pregnancy,” Robinson said.

Orca pregnancies typically last about 18 months, twice as long as human pregnancies.

Newborn calves weigh about 400 pounds and are around 8 feet long.

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The researchers say knowing which whales are pregnant or have miscarried can help scientists better understand why so many endangered orcas die very young and devise better strategies to help orca mothers raise healthy babies.

“It will be great to have a minimally invasive tool to detect early-stage pregnancies,” Seattle-based Oceans Initiative chief scientist Rob Williams, who was not involved in the study, said by email.

“The results so far are very promising,” Michael Weiss, research director of the Center for Whale Research in Friday Harbor, Washington, said by email.

“When collecting behavioral data with drones I often think whales ‘look’ pregnant, but this method provides a much more reliable, systematic way to go about this,” said Weiss, who was not involved in the study.

The Ocean Wise researchers took drone images of the northern resident killer whales for four years.

Those orcas live mostly in Canadian waters, often near the northern half of Vancouver Island — hence the “northern resident” in their name. Though their ranges overlap, these orcas, which number about 341, seldom interact with their endangered relatives, the southern residents, with a population of just 75.

“They do very much tend to keep themselves to themselves, in the same way that the transients, the mammal-eating whales, will utterly avoid southern residents at all costs,” Robinson said.

Robinson said she was meeting later in February with U.S. scientists to discuss applying the new research protocol to the southern resident killer whales, with their high rates of infant mortality and miscarriages.

She expects that the new research protocol will discover previously uncounted miscarriages in both populations.

Researchers in Canada and the United States have been using drones to photograph whales’ body shapes for a decade, usually to see whether an animal is well-fed or undernourished. They can spot an orcas’ bulging third-trimester middle but have, to date, had difficulty recognizing earlier stages of pregnancy or early miscarriages.

They can discover less-visibly pregnant whales by the presence of pregnancy hormones.

The Ocean Wise researchers say their drone-based protocol is faster and less invasive than the current method of following orcas by boat, then scooping up and chemically analyzing the floating poop that orcas leave behind.

“Anything that reduces that time from image collection to data getting out there and getting into the hands of decision makers is good news,” Robinson said.

The researchers fly a four-rotor drone, about 3 feet wide and weighing 15 pounds, under a federal research permit and at least 80 feet in the air.

Robinson said that’s high enough to avoid disturbing the whales.

“They've never exhibited any avoidance behavior,” she said.

In recent weeks, some northern resident orcas have been spotted swimming just 25 miles north of the Washington state border in Howe Sound, immediately north of urban Vancouver, B.C.

“This family has come down every year, and they'll sort of hang out for a bit, and then they'll move on,” Robinson said. “The food must be pretty good here at this time of year.”

Howe Sound is just around the corner from the mouth of the Fraser River, Canada’s largest producer of Chinook salmon – northern and southern resident orcas’ preferred food.

To protect salmon habitat, environmental groups have been fighting major industrial developments near the Fraser delta, including expansions of a Port of Vancouver container port and a liquified natural gas plant.

In January, six groups sued the Canadian government over its failure to declare an emergency to protect the southern residents, which are listed as an endangered species under Canada’s Species at Risk Act.

Orca researchers in the U.S. and Canada say it’s not too late to save the southern residents, though time is of the essence.

“If we give them the chance, and we give them the space and we give them the food, then I do think they can come back,” Robinson said.

Robinson’s title at Ocean Wise, a nonprofit that works on several ocean conservation issues, is “Director of Whales.”

She grew up near London, England, but always dreamed of working with orcas. After finishing her Ph.D. in Wales (but not on whales: it was in molecular biology), Robinson landed a postdoctorate job in Ontario, studying freshwater biodiversity.

“Then I headed over to the West Coast, which has always been my aim since I was an 11-year-old child,” she said. “I told my mom, ‘I'm going to work with killer whales on Vancouver Island.’ And in 2021, I did.”