The native Hawaiian tree snail population is plunging because of rats, say University of Hawai'i researchers.

The tree snail's numbers have plunged 85 percent on Moloka'i since 1995, say the researchers, who say the rats are eating the snails.

Hawai'i once had 750 species of land snail found nowhere else, but roughly 90 percent are now extinct, researchers have found.

The Nature Conservancy started a rat-poisoning program in 1995, but snails continued to disappear.