San Diego Natural History Museum--Your Nature Connection[San Diego County Bird Atlas Project]

Monitoring for Raptors...An MSCP Commitment

The Wildlife Research Institute, Inc. (WRI), sponsored by the California Department of Fish and Game, is developing a long-term monitoring program for the raptors addressed by southwestern San Diego County's multiple-species conservation plan (MSCP). The MSCP, adopted on 22 October 1997, encompasses 582,000 acres extending, roughly, from San Dieguito Lagoon and Boden Canyon (north of Ramona) south to the border and east to Marron Valley (east of Otay Mountain). The plan's goal is public acquisition or permanent protection of 172,000 acres.

The monitoring of raptors is recognized as a critical component of the MSCP. Why? Although once widely distributed and relatively common grassland and forest birds, some species have declined seriously. At the top of the food chain, they are the classic "miners' canary," revealing environmental toxins and changes such as loss of habitat long before we, less sensitive humans can notice them.

The objectives of the biological monitoring plan for the MSCP include documenting the protection and changes in habitats and targeted species and evaluating the effectiveness of management and enforcement. Species selected as indicators of ecosystem function for this include those dependent on coastal sage scrub, upland reptiles, and grassland-dependent raptors. Although the monitoring plan identified only the Burrowing Owl, Golden Eagle, and Northern Harrier for grassland monitoring, WRI's approach includes all of the raptors considered "covered" by the MSCP and so addresses also the Bald Eagle, Cooper's Hawk, Ferruginous Hawk, Peregrine Falcon, and Swainson's Hawk (though the last is not known to have nested in San Diego County for 68 years). To date, no comprehensive study has been conducted on any of these species within the limits of the MSCP.

WRI's objectives are to...

Determine, specifically, where these species are breeding and wintering in the MSCP area. For some, like Cooper's Hawk, a sampling approach rather than a comprehensive survey will be necessary.

Wherever possible, document the breeding success.

Characterize both successful and less successful or unsuccessful habitat.

Identify, modify, or devise, if necessary, raptor-monitoring methods, based on scientific principles, appropriate to the objectives of the MSCP's monitoring plan.

Identify needs for management and research, and opportunities for enhancing the habitat or population.

Our approach to this challenge is to develop protocols for long-term monitoring of these species, documenting their population trends. Trends need to be identified as they emerge so that environmental management decisions can be made in time to make a difference. With input of many other professionals, we have identified approximately 40 potential management units (e.g., Torrey Pines State Park, Mission Trails Regional Park, Sweetwater National Wildlife Refuge, Border Field State Park, Rancho Jamul, etc.) and other locations that could serve as controls for a long-term raptor-monitoring program. Each is being examined for its monitoring potential, with an emphasis on which raptors are present during the breeding season and winter, the repeatability of surveys, personnel safety, and disturbance to the birds. These sites will be surveyed several times through 2001 and 2002, with a final report presented early in 2003.

The museum's San Diego County Bird Atlas has already proven to be an invaluable source of relevant data. Thanks to Phil Unitt, Ann Klovstad, and the efforts of hundreds of volunteers, we have examined the results of the atlas' first four years. These not only help us identify areas important to the raptors' survival, they help characterize the relative density of populations. In addition, because of the organization of the atlas database, we can easily identify observers who are knowledgeable about specific areas where certain raptors have been sighted. We will be contacting many of the atlas participants for details of their observations, but "heads up" to those covering the MSCP area.

If there are any atlas participants or other experienced birders who would like to play a role in this exciting research project, please contact Dr. Jeff Lincer, director of research, WRI, at (619) 668-0032 or

--Jeff Lincer

Fall 2001 Wrenderings | Wrenderings Archive | Bird Atlas Introduction