The copper striped blue-tailed skink (Emoia impar) has become extinct from the Hawaiian islands, the U.S. Geological Survey said today.

The skink, a sleek lizard with smooth, polished scales and a long, sky-blue tail, was last confirmed on Kauai’s Na Pali coast in the 1960s, a USGS news release said. Repeated field surveys on Kauai, Oahu, Maui and Hawaii islands from 1988 to 2008 have yielded no sightings or specimens.

The exact causes of the skink’s extinction in Hawaii are unclear. Scientists said factors could include loss of habitat from human development and predation from introduced species.

"There’s some evidence that an invasive ant was preying on these skinks," says Robert Fisher, a biologist with the USGS Western Ecological Research Center. "That’s a new factor we’ll need to examine as we look out for other at-risk species in the Pacific islands."

This variety of skink was once common in Hawaii and can still be found on many other Pacific islands, Fisher said.

Fisher and colleague Ivan Ineichof the Muséum national d’Histoire naturellein Paris announced their findings on the skink this month in the international conservation journal "Oryx," published by Fauna and Flora International.

"No other landscape in these United States has been more impacted by extinction events and species invasions in historic times than the Hawaiian Islands, with as yet unknown long-term cascading consequences to the ecosystem," said U.S. Geological Survey director Marcia McNutt. "Today, we close the book on one more animal that is unlikely to ever be re-established in this fragile island home."