Wildlife energy: Survival of the fittest

Using a wildlife version of fitness trackers, biologists can finally measure how much energy animals need to stay alive.

Andrew Curry

10 September 2014

After attacking more than a dozen young Hawaiian monk seals, the aggressive male known as KE18 had to be banished from his island home. He now lives in a seawater pool in California, a few hundred yards from the Pacific Ocean.

Instead of assaulting more members of his species — one of the most endangered marine mammals on the planet — KE18 is now providing information that could help to keep the seals from going extinct. On a breezy June day at the University of California, Santa Cruz, an animal trainer is working to teach him to wear a metal tube containing a trio of accelerometers, tiny devices that track and log changes in velocity. It is the seal version of the fitness trackers that joggers and other endorphin addicts wear on their wrists to capture their every move.

Heaving his 200 kilograms up on the side of the pool, KE18 opens his mouth to show off his teeth and gets a fish as a reward. “We use a lot of fish and hot dogs in our lab,” says biologist Terrie Williams, who heads the mammalian physiology lab.

The hope is that data collected on KE18 will help to explain a mystery about the threatened Hawaiian monk seal (Monachus schauinslandi). Most of the population lives in the remote northwestern end of Hawaii's island chain, where four in every five pups die before reaching adulthood and the population is falling by more than 3% a year. “They end up starving to death,” says Charles Littnan, who runs the Hawaiian Monk Seal Research Program at the National Oceanic and Atmospheric Administration in Honolulu. But a much smaller population living close to the crowded beaches of the main Hawaiian islands is actually growing, despite all the human activity nearby.

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