An adult female Southern Resident killer whale nurses her calf. (NOAA Fisheries, Vancouver Aquarium)

Just below the water's surface, a 20-year-old Southern Resident killer whale nursed her baby calf — as a drone hovered 90 feet above.

The stunningly clear photo taken by the unmanned aerial vehicle is the clearest image of a wild killer whale nursing ever captured, National Oceanic and Atmospheric Administration researchers announced last week.

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"[In] previous attempts to photograph from the air, we’ve been in manned aircraft, like helicopters, so we’ve been a lot higher," NOAA Fisheries marine mammal biologist John Durban said on a NOAA podcast released last week. "This is the first time we’ve seen this kind of behavior in this kind of clarity."


An adult female Southern Resident whale is about to surface with her youngest calf, born earlier this year, alongside. (NOAA Fisheries, Vancouver Aquarium)

Researchers with NOAA and the Vancouver Aquarium spent weeks in 2015 using drones to monitor the endangered Southern Resident killer whales, which live part of the year in the waters north of Seattle.

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With only 81 such whales living in the wild, researchers are intently focused on tracking whether these creatures are growing properly and getting enough to eat, particularly since several stocks of their primary food, Chinook salmon, are also endangered.

But you can't get very close in a helicopter. And measuring wild whales is no easy task. Hence, the drones.


An adult female Southern Resident killer whale travels with her juvenile offspring. This image reveals the wide body profile of the mother, indicating that she is likely pregnant and due to have a second calf in the coming months. (NOAA Fisheries/Vancouver Aquarium)

"What we’re trying to do with the hexacopter [drone] is simply to get a camera above the whales and measure their length, so we can monitor growth, and to look at their width profile so we can see how fat they are," Durban said. "We do that by taking pictures and taking measurements from the pictures."

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In the process, the drone came back with photos of family members bringing salmon to a nursing mother whale; parents keeping watchful eyes on their offspring; and adults swimming alongside their mothers.


An overhead image of the newest member of the Southern Resident killer whale population, just days after being born to first-time mother. This image shows the small size of calves and the close bond between mother and calf that will last a lifetime. (NOAA Fisheries/Vancouver Aquarium)

Drones have been used in other wildlife conservation efforts, such as assessing the health of humpback whales off the coast of Cape Cod or even thwarting rhinoceros poachers in Africa. Proponents say drones are less intrusive and expensive than helicopters and are effective additions to the arsenal of conservation work. Some critics say little research has been done on exactly how such monitoring impacts the animals below.

In the NOAA research, the drones never flew closer than 90 feet away from the water's surface.

The subsequent images are more than just beautiful; researchers say continued monitoring with drones will track the whales' eating, growth and reproductive habits, telling humans whether they need to step in to help bolster the endangered population.

"By doing that we can help to guide management actions to perhaps help enable these whales in lean times to make sure they get an adequate food supply," Durban said.

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