What do you do when hundreds of mountain goats have become so addicted to the salt found in human urine and sweat that they are a deadly menace to national park visitors, charging at hikers and trampling vegetation?

If you run Olympic National Park in Washington State, about 100 miles west of Seattle, the answer is to airlift 375 of the bad-tempered animals - slung blindfolded beneath helicopters - to more remote areas where they will be less of a nuisance.

Authorities said they expected to shoot another 300 or so that cannot be caught.

The operation began this week. Crews equipped with tranquiliser darts and nets captured goats from ridges and rocks within the park before being airlifted to a staging area.

From there they were being driven to another part of the North Cascades, a mountain range stretching to Canada, and airlifted in crates before being released back into the wild.