San Diego Management & Monitoring Program

Golden Eagle nest platforms

May 23, 2011 - August 17, 2013 completed

Project description

San Diego National Wildlife Refuge (SDNWR) personnel and contractors constructed and installed artificial nest ledges to induce Golden Eagles (Aquila chrysaetos) to resume nesting on SDNWR and other suitable habitat nearby. Since the platforms were installed, the biologist at SDNWR has monitored them for use by eagles. Platforms were initially monitored by watching the platform and environs with a scope from a vantage point approximately a mile away. In early spring of 2016, we installed motion-triggered cameras at each of the nest platforms, and abandoned the remote surveillance we had been doing. In addition, Dr. Robert Fisher of the Western Ecological Research Center, US Geological Survey, is aware of the platforms, and looks for evidence of platform use in the data transmitted from radio-tagged eagles that are the subject of his study. To date, we only have one unequivocal record of use of the platforms by eagles. On 4 April, 2014, the refuge biologist watched a mated pair of eagles perched together on the San Miguel Mountain platform for approximately 2 minutes, after which they resumed soaring around the east side of the mountain. They occupied that hillside for the entire nesting season without nesting.

Project protocol

Name: Golden Eagle nest platform protocol

Description: The ledges are about 2 X 2 m in size, and are made of perforated sheet metal and 4” angle iron. They’re mounted on more-or-less vertical rock faces. The platforms themselves, the diagonal cables that support them from above, and the diagonal braces supporting them from below are very firmly secured, with bolts drilled into the rock and held in place with epoxy. We constructed rudimentary nests on the ledges, using branches of mission manzanita (Xylococcus bicolor) and chamise (Adenostoma fasciculata) gathered from the surrounding hillsides. We used white latex paint, squeezed from a plastic bottle, to simulate eagle droppings on the rocks surrounding the platforms.

Project spatial boundary

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Project focus

Project type: General Management

Target species: Golden Eagle

Implementing entities

Main implementing entity: U.S. Fish and Wildlife Service

SDMMP lead: Emily Perkins

Study lead: Jill Terp; John Martin