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Resource Assessment Program
1812 9th Street
Sacramento, CA 95811
(916) 445-0411

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California Swainson's Hawk Inventory


Swainson's Hawk

The Swainson's hawk was listed as a threatened species in 1983 by the California Fish and Game Commission. This listing was approved in part due to the results of the statewide survey conducted in 1979 by Pete Bloom for the CDFW (Bloom 1980). The Bloom (1980) survey provided valuable information on the nesting distribution of the species in the state. Bloom's work included conducting surveys throughout the state during one nesting season, and by using generalized habitat associations and nest site densities determined during the nesting survey, making a determination of the remaining nesting population and of the minimum percent decline of the nesting population. He estimated that there were 350 nesting pairs remaining in the state and determined this to be a 90 percent population reduction of historic Swainson's hawk numbers.

Goals of the project

In order to recover the species and maintain stable populations of the State threatened Swainson's hawk, it is essential that more complete and accurate inventory information be available regarding available habitat, breeding pair numbers, and species distribution. To this end, CDFW has initiated this study to inventory the state of California for Swainson's hawk breeding pairs and provide an up-to-date and accurate assessment of the Swainson's hawk population in California.

  • To estimate Swainson's hawk breeding pair numbers in California.
  • To test and establish a survey protocol that will be appropriate for long-term trend analysis of Swainson's hawk breeding pair numbers and habitat changes.

Primary Objectives

To achieve these goals, the project objectives are:

  • develop a scientifically based sample design and protocol for estimating Swainson's hawk breeding pair numbers statewide,
  • develop a habitat type map to correspond with Swainson's hawk range,
  • develop a protocol for a long-term trend analysis of Swainson's hawk breeding pairs, distribution, and habitat changes,
  • conduct a pilot study and an inventory of Swainson's hawk breeding pairs,
  • describe the current Swainson's hawk abundance and distribution.


Partner Name Logo California State Parks Partner Name Logo

Overview Map

Project Overview Map
Open BIOS Interactive Map

Project Stats

  • 343 Units Surveyed
  • 83 Nest Trees Located
  • Combined estimate for 2005-2006 is 2081 breeding pairs
  • Average nest height was 43' and 39' in 05-06 respectively
  • (2006 Data)


California Dept. Of Fish & Wildlife Carie Battistone
UCD Wildlife Health Center Dick Anderson
UCD Wildlife Health Center Julie Dinsdale
California Department of Fish & Wildlife Kristi Cripe
California Department of Fish & Wildlife Steve Torres
UCD Wildlife Health Center Christine Kreuder Johnson


Carie Battistone
California Department of Fish & Wildlife
1812 Ninth St.
Sacramento, CA 95814

Phone: (916) 445-3615