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California Condor Viewshed Analysis

Pinnacles NM
Patrick Flaherty
Pinnacles National Monument has been working on releasing the endangered California Condor (Gymnogyps californianus) back into the park ecosystem and surrounding area. With a wingspan of 10ft., they have the largest wingspan of any North American land bird as they fly long distances in search of carrion. Pinnacles Natural Resources Staff has partnered with Ventana Wilderness Society ( for releasing 6 initial birds. The process has had many steps and components, but birds are anticipated to be brought to the park by the end of 2003. They will be housed in a “release pen” along with a mentor adult bird to condition them to the area before the free-flying release into the park ecosystem. The release site is on a ridge in a South East portion of the park near newly acquired BLM land. The release pen is close to a private landowner ranch and the site is located outside of Pinnacles designated wilderness.

An ATV trail is to be built for ferrying water and lead-free animal carcasses to the top of a ridge that rises over 600 ft above the North Chalone Creek bed below. From a dirt road up a canyon below the release site the proposed trail was GPSed by the trail builders and the lead condor biologist then converted to a shapefile. A local trail designing expert will build the trail after environmental compliance and direct consultation with the park resource staff.

Before building the trail a viewshed analysis was performed using the ArcView 3.2 spatial analyst extension. The analysis helped to visualize what surrounding areas would be in condor view from the release pen. Condors are curious birds by nature and in minimizing human presence near the site, hopefully the birds will stay away from harmful future human–induced confrontation. After running the viewshed analysis with the associated DEM for the area, the proposed ATV trail was found not to be in direct sight from the condor pen.

Other trail/road features were placed on the map in case a different approach to water/carcass deposition was necessary. Alternate routes give the project options for delivery of water, carcasses, and biologists to get to the release site. The viewshed has given the Pinnacles Resource Staff an awareness for how the condors view the area around them and how we may better minimize human and vehicular traffic. The spatial analysis can also visualize the peaks condors may fly to upon their release. GIS will figure prominently into future planning, tracking of birds and in working with local landowners.

As of September 2002, 6 young condors and 1 mentor 14 yr. old bird have been deleivered to the release pen. Anticipated release is for mid-November.

April 08, 2004