After Being Hunted to Near-Extinction, New Zealand Sea Lions Are Reclaiming the Mainland

Around 200 years ago, the once-flourishing population of New Zealand sea lions was completely hunted off the mainland and driven southwards to other islands. But in 1993, one female gave birth to a pup on the mainland, and since then, the population has bounced back with a blubbery vengeance—they've managed to wiggle themselves all the way from the ocean to places like golf courses, swimming pools and forests, reports Charlotte Graham-McLay for the New York Times.

There are currently around 12,000 New Zealand sea lions, and the species is still listed as endangered. Previous distribution models for the New Zealand sea lions didn't completely reflect where the animals were living or moving on the mainland, so the team set out to create a more comprehensive dataset by combining algorithmic modeling with field data, according to a press release.

"It’s one thing for wildlife rangers to look out for sea lions on sandy beaches, but it’s another challenge for them to tromp through forests to find baby sea lions hiding under the trees," lead author Veronica Frans, a Ph.D. student at Michigan State University, says in a statement.  

They mapped out different types of habitat—such as forest, sand, grass, slopes and cliffs—as well as human-created barriers like roads, farms and neighborhoods. All these elements can help scientists understand where a sea lion could live, how it would get there and the challenges it may encounter along the way. They published their findings this week in the journal Methods in Ecology and Evolution.

"While we can’t know for sure where female sea lions will go on the mainland, we can use models to make helpful predictions," Frans says in the press release. 

Using the model, Frans counted 395 spots that could serve as sea lion habitat. However, human-made obstacles such as roads and fences affect about 90 percent of those spots, reports the Times.

"Nearly 400 sites seem like an incredible potential for a bright future for these sea lions. All signs point to many more sea lion pups in the future, if we do our best to welcome them," Frans says in the press release.

Mother sea lions can trek more than a mile into a forest for safety. These mothers are remarkably protective, and a forest keeps pups far away from aggressive adult males and shelters them from the elements. However, the journey into the forest isn't easy—sea lions get hit by cars while crossing roads and they may encounter other barriers, like fences, that limit their movement, reports Isaac Schultz for Gizmodo.

Furthermore, not all New Zealanders are thrilled about the sea lions' comeback. Accidentally stumbling upon a mother and pup can be startling, since mothers are loud and protective of their young. The sea lions' presence can also be disruptive; in one instance, authorities shut down a road for a month to protect a mother and her pup, which didn't bode well with some residents. Some people have gone as far as intentionally killing the sea lions, the Times reports.

"One way [modeling] will help is the public awareness and engagement and knowing which communities to target as the population expands," Laura Boren, a science adviser for New Zealand’s Department of Conservation, tells the Times. "We can get people ready for sea lions coming to their town."

Despite the sea lions' grand return, it doesn't mean people should be planning their days around them. There's a way to live together, Frans tells the Times.

"It’s difficult because we imagine protected areas being areas that kind of kick people out, but people are allowed to be integrated in those places," she says. "It’s more that we find a balance."

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Rasha Aridi is a science journalist based in Richmond, Virginia. She has written for Science magazine and Science News for Students. You can find her portfolio at rashaaridi.com.