This is Bird Note.

The bald eagle makes the largest nest of all birds in North America.

Rather than building a new nest every year,

a pair of eagles will repair their nest with new tree branches and reuse it.

During fieldwork in British Columbia in 2015,

scientists came across an eagle nest made largely out of dried kelp.

Back in the 90s, though, that very nest had been made out of tree branches.

Kelp, a type of seaweed, ended up in that eagle's nest

thanks to a furry neighbor.

By 1930, sea otters

had been hunted to near extinction

in British Columbia.

But since their reintroduction in 1969,

they've had a big impact

on the coastal ecosystem.

By feeding on sea urchins, which destroy kelp, otters have aided the growth of underwater kelp forests.

When kelp dies a natural death, it washes up on the beach and dries out, and sometimes ends up in an

eagle's nest.

For Bird Note, I'm Michael Stein.

Support for Bird Note is provided by Sarah Mearner and Craig McKibbon from Seattle, Washington,

and generous listeners around the world.