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Distribution, nesting activities, and age-class of territorial pairs of golden eagles at the Altamont Pass Wind Resource Area, California, 2014–16

Open-File Report 2017-1035
Prepared in cooperation with Next Era Energy, Inc., U.S. Fish and Wildlife Service, East Bay Regional Park District, and The Peregrine Fund, Inc.
By:  and 
https://doi.org/10.3133/ofr20171035

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Abstract

The substantial numbers of golden eagles (Aquila chrysaetos) killed by collisions with oldgeneration wind turbines each year at the Altamont Pass Wind Resource Area (APWRA) in California has been well documented from previous studies. Few eagle nests have been documented in the APWRA, however, and adults and subadults 3+ years of age killed by turbines were generally not associated with nearby territories. We searched a subset of randomly selected survey plots for territorial pairs of golden eagles and associated nesting attempts within the APWRA as part of a broader investigation of population dynamics in the surrounding northern Diablo Range. In contrast to limited historical observations from 1988 to 2013, our surveys documented up to 15 territorial pairs within 3.2 kilometers (km) of wind turbines at the APWRA annually, 9 of which were not previously documented or only observed intermittently during historical surveys. We found evidence of nesting activity by adult pairs at least once during our study at six of these territories. We also determined that 23–36 percent of territories identified within 3.2 km of the APWRA had a subadult pair member, but that no pairs with a subadult member attempted to nest. These data will be useful to developers, wildlife managers, and future raptor studies in the area to evaluate and minimize the potential effects of wind energy or other development activities on previously unknown territorial pairs in the area.

Suggested Citation

Kolar, P.S., and Wiens, J.D., 2017, Distribution, nesting activities, and age-class of territorial pairs of golden eagles at the Altamont Pass Wind Resource Area, California, 2014–16: U.S. Geological Survey Open-File Report 2017–1035, 18 p., https://doi.org/10.3133/ofr20171035.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Methods
  • Survey Results
  • Discussion
  • Acknowledgments
  • References Cited
  • Appendix 1. Number of Completed Individual Surveys for Focal Sample Plots Overlapping with the Altamont Pass Wind Resource Area, California, 2014–16
  • Appendix 2. Observations of Territorial and Nesting Activities of Golden Eagles at the Altamont Pass Wind Resource Area, California, 2014–16
Publication type Report
Publication Subtype USGS Numbered Series
Title Distribution, nesting activities, and age-class of territorial pairs of golden eagles at the Altamont Pass Wind Resource Area, California, 2014–16
Series title Open-File Report
Series number 2017-1035
DOI 10.3133/ofr20171035
Year Published 2017
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Forest and Rangeland Ecosystem Science Center
Description iv, 18 p.
Country United States
State California
Other Geospatial Altamont Pass Wind Resource Area
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details