Return of the Hawk : Hatchings Boost Renewal of Breed in Colorado River Area

After six years of trying to reintroduce a species of hawk that disappeared decades ago from its native grounds in the Lower Colorado River Valley, state and federal officials have succeeded with a pair of birds that met and mated in the wild.

Two eggs hatched in a nest built by Harris’ hawks in a tall paloverde tree a few miles north of Yuma, Ariz. It is the first time in 30 years that the slim, black and white and chestnut-colored hawks have bred in the area.

“In another week the chicks will be testing their wings,” said Gary Ferrier, a spokesman for the Bureau of Land Management office at Yuma. “This is what we’ve been hoping for. It is very exciting.”

In the early 1950s, naturalists declared the Harris’ hawk extinct in the region--victims of dam and irrigation system development that destroyed the once-plentiful mesquite, cottonwood and paloverde trees the birds prefer.

The project to reintroduce the birds between Blythe and Yuma is a joint effort involving the Bureau of Land Management, the California Department of Fish and Game, the Arizona Department of Fish and Game, University of California, Santa Cruz, and falconry enthusiasts. The Bureau of Reclamation has also participated.

Despite this sizable cooperative effort, “it’s been a nickle-and-dime project from the start,” Ferrier said, adding that the $15,000 invested so far “has been hard to come by.”

Since nearly half of the 100 hawks released along the 70-mile stretch of river over the last five years--all of which were bred in captivity--either failed to mate or flew south to Mexico or east to Arizona, the sighting of the Harris’ hawk nest came as a welcome surprise.

“We had thought the project was a failure because we expected nesting earlier,” said Ron Schlorff, a wildlife biologist with the California Department of Fish and Game’s Nongame Wildlife Program. “This has changed our mind.”

Although never plentiful in California, Harris’ hawks once soared over the length of the Colorado River, feeding primarily on prey such as rabbits, quail, snakes and lizards.

“People unintentionally knocked out the primary predator in that food chain,” said Brian Walton, director of the Santa Cruz Predatory Bird Research Group of UC Santa Cruz. “We are trying to do something to reverse that trend.”

This year, Walton said the group plans to release at least 20 more Harris’ hawks along the river. At the same time, the state and federal agencies plan to restore the birds’ natural habitat by planting more native trees in the area.

Even these efforts, however, will be doomed unless traffic in nesting areas can be kept to a minimum. Therefore, the precise location of the nest with the newly hatched eggs has not been disclosed.

“It is critical that we restrict human contact at this stage,” Walton said. “I have no doubt those babies will survive if people will give them half a chance.”