This is scientific American's 60 second science. I'm Christopher Intagiyata.

Today we have sophisticated bois packed with instruments and robotic underwater drones.

But more than a century ago, the seas were surveyed by different types of autonomous data gathering instruments,

which also happened to be alive.

We just call them sea otters and white sharks and blue and tuna.

Kyle Van Houghton is director of science at the Monterrey Bay Aquarium.

And what he means is that marine mammals and fish and

seabirds concentrate unique chemical clues about the ocean and what lives in

it within their tissues. In their bones, in their feathers, in their vertebrae, in their earwax.

For his most recent study, Van Houghton needed to locate feathers

from some long dead birds.

Let's see, so I'm just looking here, so that was a

Boer's petrol from French frigate shoals. I had the database open in front of me

here. Molly Hageman, who describes herself as a librarian for dead

animals at Honolulu's Bishop Museum was able to help.

So that one was collected in May of 1891, and then we also had a brown knotty from

1895.

The scientists analyze the ratios of heavy to light nitrogen isotopes within those old feathers compared to ratios in modern day specimens.

And they found that Pacific seabirds of yore ate diets dominated by fish. But the birds of today, they were fishing

farther down the food web, and seemed to be eating nearly twice as much squid as their ancestors

did, maybe due to the combined effects of commercial fishing and climate change.

The details are in the journal Science Advances.

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