Modeling the spatial behaviors of reintroduced California condors as a predictive management tool for assessing the impacts of wind farms

Background/Question/Methods   The California condor was reintroduced to its former range in the Sierra Mountains of Baja California, Mexico in 2002 by the Zoological Society of San Diego. The goal of the reintroduction program is to establish a self-sustaining breeding population that will eventually link up with other managed condor populations in the USA. The Baja Sierras was chosen as a condor reintroduction site because of its pristine habitat, isolation and extensive steep ridgelines that generate the strong and consistent wind conditions that enable condors to fly with energetic parsimony. These winds also make the ridgelines attractive to utility companies seeking to erect wind farms to meet the increasing demand for clean, renewable energy. At least three large-scale wind farm projects are currently proposed for the Baja Sierras. These projects are in close proximity to each other and comprise a considerable risk of injury and mortality to avifauna in the region. Information is urgently required on condor movement patterns and habitat use so that the risks to the birds posed by wind energy developments can be assessed and minimized. Unfortunately, published studies on condor spatial ecology are lacking. Condors travel extensive distances from their communal roosting sites while searching for food carcasses and may maximize foraging efficiency and minimize the energetic costs of wide-ranging foraging by static soaring on turbulent uplifts. If wind conditions determine condor foraging efficiency, then condor habitat use and specific route choices will be predicated on the attributes of the prevailing winds specific to a region. I am characterizing condor spatial ecology and energetics with a view to constructing a model of condor habitat use. I am matching condor movements and internal state to the environmental attributes within their habitat using the following telemetry data: 1) GPS locations acquired from every condor released in Baja; 2) condor heart rates and powered vs. gliding flights recorded using miniaturized digital biologgers; 3) the climate conditions experienced by each condor, recorded by a series of meteorological stations installed throughout their range.

Results/Conclusions   Cohesive, seasonal patterns of condor spatial behaviors are already emerging as the birds expand their ranges and follow the Sierra ridgelines during foraging flights of greater distances. This information can be incorporated into the planning stages of wind energy developments to predict and reduce the risk of impacts on condor populations.