This is Bird Note. Only the most intrepid birders lay eyes on the striking

cobalt feathers of the island Scrub J. One of the rarest songbirds in the U.S.

You'll have to take a boat about 20 miles to California's Channel Island's

National Park. Then, trek into the Chaparral Woodlands of Santa Cruz Island.

There, an estimated 1700 island Scrub J's live in monogamous pairs,

nesting within island Scrub oak trees. The J's have few natural predators,

or competitors for food, letting them grow larger than their continental counterparts.

But the bird's isolation makes them susceptible to diseases such as

West Nile virus, which has an 85 percent mortality rate among related

California Scrub J's. Though the mosquitoes that transmit the virus don't

like the island's chilly temperatures, climate change could help them spread. To

prepare, scientists have launched an avian vaccination campaign. Another

option being considered? Relocate some J's to nearby Santa Rosa Island, where

they could help re-establish native oak trees when they bury the acorns in

the ground. A double biodiversity win for bird note. I'm Michael Stein.