For the birds

Mar 01, 2011 By Janet Wilson
UCI biologists are creating a welcoming habitat near campus that they hope will help the cactus wren thrive. Credit: Steve Zylius / University Communications

Kristine Preston steps softly onto UC Irvine's Ecological Preserve, 62 acres of cheerful wildflowers and sweet-smelling sage scrub tucked above University Hills.

"We had a pair of birds using this plant two days ago, which is just incredible," she whispers, pointing to a large prickly pear cactus. The 40-year-old plant is one of a whole stand recently transplanted from a campus area slated for development to a formerly weed-strewn four-acre patch of the preserve.

Preston, science program director for the of Orange County, is glad to see the cacti seem to be doing well. But she's more interested in what could be hiding in the dense, bristling pads. Slowly, she draws close, binoculars at the ready.

Disappointment. No noise, no flash of .

Preston is on the hunt for a cactus wren, a cheeky brown-and-white bird once common in coastal Southern California. She's thrilled that she spotted a male and female in this little stretch of sage scrub earlier in the week. Born last year in nearby territory, the male was caught and banded with orange over white on his right leg.

He appears to have taken up with a female born in 2009, banded in red and dubbed a "floater" because she has no established territory. The male's father rules the adjacent land, so if this pair has already made itself at home in the newly transplanted cactus, it will be a major success — with babies possible by spring.

But even when cactus wrens do hatch, they face tough odds finding their own home. Most of the bird's habitat has been chopped, lopped and crisscrossed by highways, housing tracts and shopping malls. The Laguna Beach fire of 1993 and Santiago fire of 2007 each killed most of the birds on county reserve lands and scorched 75 percent of their precious remaining habitat.

"There's been massive overdevelopment, and the fires really hurt," says Peter Bowler, a UCI senior lecturer in ecology & evolutionary biology who has been studying or teaching at the campus since 1970. He gazes from the hilltop preserve at a slope filled with houses. "This all used to be wilderness."

But biologists in suburbia learn to work with what they've got, as do the creatures they study. Bowler, Preston and Margot Griswold, a veteran restoration ecologist hired by the Orange County Transportation Corridor Agencies, are spearheading a collaborative effort to bring the birds back.

The four-acre cactus restoration program is part of a $600,000 project funded by the California Department of Transportation and the Orange County Transportation Authority in exchange for bulldozing sage scrub for roads elsewhere. Another eight acres at the preserve will be stripped of invasive plants with no natural predators that are crowding out beautiful native grasses and wildflowers.

The aim is to nurture a loose chain of cactus wren habitat patches stretching from near the Fashion Island mall to above the Coyote Canyon Landfill. These bits of habitat could serve as signposts to cactus wrens that there are other homes available — which could prevent inbreeding and genetic loss.

The transplanted mini cactus forest, on a knobby knoll and adjoining slopes above State Route 73, is a key piece. Biologists hope the normally sedentary birds will perch there, spy the distinctive outlines of existing cacti and sage scrub on the other side of the freeway and fly over eight lanes of traffic to reach it.

"The UCI preserve has one of the largest wren populations in the area, and in addition to providing new cacti for them to use here, cacti will be placed in line-of-sight locations to link the preserve with other populations," Bowler says. "This is a very exciting project."

On a sparkling morning at the preserve, birdsong rises over the drone of traffic and planes taking off from John Wayne Airport. Dozens of birds are happily chirping, whirring and circling. A flock of tiny bushtits dances between silvery green artemisia and blooming pink lemonade berry bushes.

Sparrows, towhees, even Bewick's wrens and federally threatened California gnatcatchers are all visible. The cactus wrens, though, have vanished. A good-sized Cooper's hawk perches hungrily on a fence post, worrying Preston.

The cactus wren has a long, hooked beak; a razor-top head; and a sleek, dark bar across its cheeks and beady red eyes. It's a medium-sized bird that takes shelter from hawks, snakes and other predators in a cactus's piercing needles. But it doesn't always get there in time.

Slowly, Preston circles the preserve, narrating a virtual wren soap opera: A first "wife" was booted out by a younger "wife" and flew across the toll road, finding a new mate and home. There have been a lot of cactus wren "divorces" lately, Preston says, and she's not sure why.

The male bird she's looking for may have been driven out by its father, anxious to preserve his own precious habitat. Preston has also forgotten her bird-call tape, which she hoped to use to rustle up the wren. It's been that kind of morning. Still, it's a beautiful day.

There's a click-clicking in a low tangle of buckwheat and coastal cholla cacti. It is a cactus wren, annoyed by noisy intruders but not the one she's seeking.

Finally, Preston turns to head back to her car. Something catches her attention, way back on the first cactus. It's her bird, perched on the very top, preening and cocking an eye at the blue sky.

Explore further: A step into the unmown creates a 'win-win' for wildlife and humans

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