Scientists have deployed all kinds of technology to study wildlife, from satellite tags and collars to field cameras. Now, a new test has shown that they could use unmanned aerial vehicles (UAVs) to study wildlife populations, too. For the first time, scientists from NOAA Fisheries and the Vancouver Aquarium used a camera-equipped UAV to take gorgeous, straight-down photos of northern resident killer whales, animals that swim in the waters near Vancouver Island, British Columbia. Their paper was recently published in the Journal of Unmanned Vehicles.

You can tell a lot about a whale from a photo. From this photo, for example, scientists were able to determine that the top female "appears skinny and in poor condition," while the female in the middle appears healthy. The whale at the bottom of the photo is pregnant—you can tell because her body bulges near the ribcage. Photo credit: NOAA, Vancouver Aquarium

They flew a hexacopter UAV (named for its six rotor blades) about 100 feet above the whales so they wouldn’t notice its presence. When whales were in the frame, the pilot used a remote link to trigger the capture of still images on the camera's flash memory. The UAV was equipped with both a high-resolution digital camera—which provided enough detail that the scientists could distinguish between the unique markings on individual whales—and a pressure altimeter, which told them the exact altitude of the UAV. Combining this information with the focal length of the camera lens allowed them to calculate the size of objects to an accuracy of 5 centimeters. 

Photo credit: NOAA, Vancouver Aquarium

“Because the image resolution is so great,” John Durban, a marine mammal ecologist with NOAA Fisheries, said, “we can monitor very small changes in an animal’s condition from year to year,” Durban said.

The UAV flew a total of 60 successful missions last year, snapping photographs that aren't just beautiful, but useful too, allowing scientists to “make very precise measurements from them,” Durban said. “We can’t put a whale on a scale, but we can use aerial images to analyze their body condition—basically, how fat or skinny they are.”

By examining the photos, scientists can figure out (among other things) if the whales are eating enough; these northern whales, which are categorized as threatened under Canada’s Species At Risk Act, eat mostly Chinook salmon. The dwindling numbers of Chinook could be adversely affecting the whale population.

Photo credit: NOAA, Vancouver Aquarium

Scientists have used manned aircraft to do this sort of thing for decades, but UAVs provide a number of benefits: They're less expensive to fly, can take off from small vessels, and are much quieter than manned planes, allowing scientists to observe the whales without bothering them.

Two killer whales playfully butt heads. Photo credit: NOAA, Vancouver Aquarium

Researchers conduct a summer census annually to determine how many whales have died. "But mortality is a pretty coarse measure of how well the population is doing because the problem, if there is one, has already occurred," Durban said on the NOAA Fisheries blog. The UAV, however, "can give us a more sensitive measure that we might be able to respond to before whales die."