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Current Status:

Loss of riparian woodland habitat to urban and agricultural development, livestock grazing, flood control, and water development projects continue to affect least Bell's vireo populations. Nesting parasitism by the brown-headed cowbird also causes problems.

Achievements:

Since this species was listed in 1986, the U.S. population has increased from about 300 pairs to 500 pairs. Two populations, one at Santa Margarita River and the other at Prado Basin, now consist of 100 or more pairs, while as recently as 1986, the Prado Basin population contained only 19 pairs. Cowbird trapping, as well as habitat management and enhancement, apparently are responsible. In another hopeful development, vireos have been sighted in areas where they were previously undetected.

Two years of informal section 7 consultations between the Fish and Wildlife Service, Sweetwater Authority, and Army Corps of Engineers have led to a tentative agreement to eliminate an upstream sediment detention basin and sediment transport project from an area containing more than 30 vireo pairs. The Sweetwater Authority has agreed to address the Sweetwater Reservoir's sedimentation problem with a plan to remove surface sediment only below the high water line and only when the vireos are absent. Thirty years of sand extraction operations also have ceased. The disturbed upstream habitat must be revegetated and occupied by vireo pairs before surface sediment removal disturbs an equal amount of downstream habitat. Section 7 consultations with the Federal Highway Administration over various highway projects and bridge construction also are under way.

In addition, in 1991, the Service received two section 10 permit applications and final draft Habitat Conservation Plans from the San Diego Association of Governments for the San Diego and Sweetwater Rivers. The Habitat Conservation Plans are under review, and a draft environmental assessment is being prepared.

Current Recovery Needs:

Continued population monitoring, cowbird management, biological research, watershed-specific management plans, and habitat conservation and restoration are needed.

Section 6 Funding and Activities:

The California Department of Fish and Game received $90,000 in FY 1991 and again in FY 1992 for least Bell's vireo management. In FY 1991, $45,000 were used for cowbird control and $45,000 for population surveys. In FY 1992, it was recommended that $60,000 be spent on cowbird control and $30,000 on population surveys.

Partnerships

US. Marine Corps: The Fish and Wildlife Service and the Marine Corps signed a 1989 Memorandum of Understanding (MOU) for vireos within proposed critical habitat on Camp Pendleton. Resulting actions have helped control cowbirds, increasing vireos from 15 territories in 1980 to 259 in 1991.

California Department of Fish and Game: The Department assists with cowbird control and vireo monitoring.

Recovery Plan Status:

Agency draft plan.