As of last month, scientists studying walruses can map out just where the blubbery animals hang out in the coastal Pacific—and where they’ve hung out for the past 160 years, NPR reports.

A new database years in the making documents the locations of walrus “haulouts”—when the marine mammals venture onto the beach or ice to rest between feeding escapades, often in groups that number in the thousands. Why these hordes of walruses gather where they do is somewhat of a mystery. Haulouts aren't always on a beach that’s near their hunting grounds, and they will switch locations seemingly at random after years of flocking to the same spot annually.

And because of climate change, the options for resting spots are becoming limited since the ice floes that have been haulout hot spots in the past are melting. Female and young walruses especially tend to gather on ice, since haulouts can be somewhat risky for them, should there be a stampede triggered by the appearance of a predator or another unpleasant surprise. Now, some of those ice floes are no longer available to them. 

Walruses on land have been fascinating naturalists, observers, and hunters for centuries. In 1874, naturalist Henry Wood Elliott described a gathering of 150 male walruses in Alaska as looking like “so many gnomes or demons of fair romance,” as NPR quotes. (He was clearly appalled by them: "The longer I looked at them the more heightened was my disgust; for they resembled distorted, mortified, shapeless masses of flesh," he wrote.) The new database’s creators, including both U.S. and Russian scientists, referenced old ships’ logs dating back to the 1850s, oral histories from walrus-hunting Native peoples, and books and articles from Russia, Canada, and the U.S. The resulting database logs 150 known walrus haulouts, documenting how many walruses have been observed there, the ages and sexes that tend to congregate, what seasons it has been used during, and what decade walruses were last seen there.

Hopefully, tracking walrus haulout patterns will help scientists discover how they choose their resting spots, and how those spots are evolving due to climate change.

[h/t NPR]

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