How drones can help leopard seals

Scientists are using drones to monitor and measure the Antarctic mammals.

A Leopard seal (Hydrurga leptonyx) rests on an ice floe along the Antarctic Peninsula

A leopard seal rests on an ice flow along the Antarctic Peninsula © Ty Milford / Getty

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Weighing in at more than half a ton, leopard seals are formidable predators that act as indicators for the condition of the whole ecosystem.

Rather than catching and weighing leopard seals one by one, scientists are using drones to gather the same information at a much faster rate.

“We can get measurements that are just as good, or better, without ever bothering the animals,” says Douglas Krause, a research scientist at Antarctic Ecosystem Research Division (AERD). “Catching a single seal can take hours, but the drone can photograph every seal on a beach in a few minutes.”

To test just how efficient the drones are, the scientists caught and measured the same group of seals that the drone photographed. Length and weight measurements were accurate to within 2 per cent and 4 per cent respectively.

The main advantage, however, was the time saved. It took just two people 20 minutes to gather data on all 15 leopard seals included in the study using a drone. Not only this, but the seals were unaffected by the drone if it remained above 23 metres. 

In comparison, five people took more than four hours to catch and measure the leopard seals.

While leopard seals are an apex predator, their prey – penguins and fur seals – are mesopredators, feeding on krill.

These shrimp-like crustaceans are harvested commercially, so it is especially important to monitor leopard seals to ensure that populations of all species remain stable.

“We’re always looking for more efficient ways to collect data that informs decisions on how to manage resources,” said George Watters, director of AERD.

The drone data collected will be used by fisheries to assess how much krill can be caught sustainably each season, without negatively affecting the populations of penguins and fur seals, and thus leopard seals.

Read the full paper in Plos One.

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Read more wildlife news stories in BBC Wildlife Magazine