U.S. Agency Urges More Protection for Rare Songbirds : Wildlife: Officials call a strip of land along the Santa Clara River in Ventura County vital to the endangered least Bell’s vireo.

A federal wildlife agency on Friday proposed stepping up protection against development on a lengthy strip of land along the Santa Clara River in Ventura County considered critical to the survival of a small endangered songbird.

To help re-establish the population of the least Bell’s vireo, the U.S. Fish and Wildlife Service proposed “critical habitat” status for 48,020 acres in six counties--Ventura, Santa Barbara, Los Angeles, Riverside, San Bernardino and San Diego.

Bobbe Dorsey, a board member of the Ventura branch of the National Audubon Society, said she is delighted with the proposal.

“Any action of the kind that will preserve the Bell’s and its habitat is great,” she said. “It’s an endangered species and we should save them.”

Development is not banned in critical habitats, but the designation triggers another layer of review by federal agencies.

The U.S. Endangered Species Act of 1973 forbids federal agencies from allowing construction that would destroy or otherwise harm habitat that is critical to endangered species--unless an exception is granted.

A Fish and Wildlife spokesman, however, said much of the acreage involved in the agency’s proposal is already considered unsuitable for development because of its proximity to flood plains.

The proposed designation would not affect Ventura County plans to build a $53.1-million jail close to the Santa Clara River near Santa Paula, said Arthur E. Goulet, director of Ventura County Public Works. Construction began along the river in June and the jail is expected to open in spring, 1994.

But he said the county is working with Fish and Wildlife officials to avoid harming any birds nesting nearby.

“What we’re trying to do with Fish and Wildlife is develop some sort of management plan that takes into account all of the goals of the different parties.”

Only about 500 nesting pairs of least Bell’s vireos remain in the United States, and about 90% of them nest in the proposed critical habitat area. Several hundred more pairs breed in northern Baja California, but biologists do not have an accurate count in that area.

Larry Salata, a Fish and Wildlife biologist who has studied the birds for 12 years, said the fate of the endangered vireo parallels the destruction of inland wetlands throughout California since the turn of the century.

“About 90% of those kinds of wetlands have been lost,” he said. “Yet they represent one of the most significant wildlife habitats in the state and nation.”

Before the proposal can become law, at least two public hearings will be scheduled. The Fish and Wildlife Service must make a decision by January, 1993.

Under the plan, the critical habitat would consist of about 4,240 acres in an lengthy strip of land along the Santa Clara River in Ventura and Los Angeles counties, most of which is in Los Angeles County. It also would include 9,260 acres along the Santa Ynez River in Santa Barbara County; about 9,135 acres near the Santa Ana River in Riverside and San Bernardino counties, and, in San Diego County, 25,380 acres along the Santa Margarita, San Luis Rey, Sweetwater, San Diego and Tijuana rivers and the Coyote and Jamul-Dulzura creeks.

The Least Bell’s Vireo Description: Four to five inches long, with grayish head, back and tail and whitish throat and breast.

Habitat: Dense thickets, shrubs and trees along streams and rivers.

Range: Although once common in California from Santa Clara County south to Baja California, the bird is now found only in small areas of San Diego, Santa Barbara, Ventura, Los Angeles, San Bernardino, Riverside and Orange counties.

Status: The U.S. Fish and Wildlife Service listed the bird as endangered in 1986. The California Department of Fish and Game listed the least Bell’s vireo as endangered in 1980.

Song: Sings as if through clenched teeth: “Cheedle cheedle chee? Cheedle cheedle chew!” Inflection rises in the first half and falls in the second half, as though answering its own question.