JOINT BASE LEWIS-MCCHORD, Wash. — An undeveloped stretch of native prairie in south Puget Sound offers one of the few habitats in the world where a two-inch colorful checkered butterfly thrives. It also happens to be the main artillery impact range for Joint Base Lewis-McChord.

The Army’s Stryker combat brigade and other troops regularly practice military maneuvers and live-fire training on acres of scenic, open grassland where a small population of Taylor’s checkerspot butterfly feed on nectar of native blooms, mate, and lay eggs.

The butterfly’s listing as a federal endangered species last fall ‘‘has the potential to cause major restrictions on training,’’ said Jeffrey Foster, an ecologist at the military installation.


That has the Army working to boost the numbers of butterflies, once found at more than 70 sites in Puget Sound, Oregon, and British Columbia, but now down to 14 sites. The effort mirrors others by the Army at bases across the country.

From Maryland to Louisiana to Colorado, the Army has been conserving buffer areas around bases to limit urban development, while also preserving and restoring habitat for rare species such as the red-cockaded woodpecker and the golden-cheeked warbler.

So far, the program has preserved more than 200,000 acres of land.

At Lewis-McChord, 44 miles south of Seattle, the program is helping not only the Taylor’s checkerspot butterfly but also the streaked horned lark and Mazama pocket gopher.

Last October, the US Fish & Wildlife Service concluded that the Taylor’s checkerspot was in danger of becoming extinct and designated nearly 2,000 acres in Clallam County, Puget Sound, and Oregon’s Willamette Valley as critical habitat for the creature.

The agency said it considered ‘‘military training under present conditions a threat to the short-term and long-term conservation of the Taylor’s checkerspot.’’