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SOUTHERN CALIFORNIA – It may not be the most intuitive place for an endangered species to recover, but the staff of the U.S. Marine Corps Base Camp Pendleton have worked hard to protect habitat for the least Bell’s vireo (Vireo bellii pusillus).

USGS researcher holds an endangered least Bell's vireo
USGS researcher holds an endangered least Bell’s vireo marked with a brightly-colored ID tag. (Credit: Barbara Kus, USGS. Public domain.)

The project has been a collaborative effort between biologists from the USGS Western Ecological Research Center (WERC), the U.S. Fish and Wildlife Service, and the U.S. Marine Corps.

Watch a Marine Corps video on this exciting project.

The least Bell’s vireo was once common throughout its range extending from California to northern Baja California, Mexico. However, brood parasitism by the brown-headed cowbird, in which a female cowbird lays her eggs in the nests of other species, and other threats caused least Bell’s vireo numbers to decline significantly. By the time it was listed under the Endangered Species Act in 1986, scientists estimated that only 300 breeding pairs remained in California.

Since then, the Marine Corps has worked closely with WERC’s Dr. Barbara Kus and team to identify and conserve important habitats for the least Bell’s vireo. In 2017, the number of breeding pairs at Camp Pendleton was six times what it was before the listing.

Dr. Kus and colleagues are studying the genetics, distribution, ecology, and demography of the least Bell’s vireo from southern California to Baja California. Learn more about how their findings are guiding the recovery of this endangered bird on our website.

Lisa Allen and Colin Lee
Colin Lee, wildlife biologist with the Marine Corps Base Camp Pendleton Game Warden’s Office, and Lisa Allen, wildlife biologist with the U.S. Geological Survey, discuss conservation methods while searching for an endangered species of bird, the Least Bell’s Vireo, at the Santa Margarita river on Camp Pendleton, Calif. May 16, 2018.  (U.S. Marine Corps photo by Lance Cpl. Drake Nickels)
Lisa Allen with LBV hatchling
Colin Lee, wildlife biologist with the Marine Corps Base Camp Pendleton Game Warden’s Office, searches for the endangered Least Bell’s Vireo at the Santa Margarita River on Camp Pendleton, Calif., May 16 2018. (U.S. Marine Corps photo by Lance Cpl. Drake Nickels/Released)


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