Swainson's Hawk

Conservation Genetics of Threatened Swainson's Hawks

The Swainson's Hawk is a state-listed threatened species in California and is believed to be in decline (CDFG 2002; England et al. 1997). Once flying throughout lowland regions of California, now Swainson's hawks are found only in portions of the Central Valley and Great Basin regions where suitable nesting and foraging habitat still remains. Estimated numbers have dropped from over 17,000 pairs in the early 1900's to 800 pairs (1994). Combined estimate for 2005-2006 is 2081 breeding pairs according to a CDFG study. We worked with the California Swainson's Hawk Technical Advisory Committee and California Department of Fish and Game to supply information about genetic diversity, population structure, and taxonomic distinctiveness of Swainson’s Hawks in California (publications below).

Hawk of Galápagos Islands has Swainson's Hawk as closest relative

In a collaboration between our lab and Dr. Patricia Parker's research team at the University of Missouri, Josh Hull analyzed Galápagos hawk DNA and discovered strengthened evidence that the closest species relative of the Galápagos hawk is the Swainson's Hawk. This work is published in Biological Journal of the Linnean Society, the direct descendant of the oldest biological journal in the world, which published the papers by Darwin and Wallace.  Follow the links below to learn more.


Reduced MHC and neutral variation in the Galapagos hawk, an island endemic. Bollmer JL, Hull JM, Ernest HB, Sarasola JH, Parker PG. BMC Evolutionary Biology 2011, 11:143.

Hull JM, Savage WK, Bollmer JL, Kimball RT, Parker PG, Whiteman NK, Ernest HB. 2008. On the origin the Galápagos hawk: An examination of phenotypic differentiation and mitochondrial paraphyly.  Biological Journal of the Linnean Society. 95:779 - 789.

Hull J.M., R. Anderson, M. Bradbury, J. Estep, H. B. Ernest. 2008. Population structure and genetic diversity in Swainson’s Hawks (Buteo swainsoni), implications for conservation. Conservation Genetics 9:305-316.

Hull J.M., W. Savage, J.P. Smith, N. Murphy, L. Cullen, A.D. Hutchins, H.B. Ernest. 2007. Hybridization among Buteos: Swainson's Hawks (Buteo swainsoni) × Red-tailed Hawks (Buteo jamaicensis). The Wilson Journal of Ornithology,.119(4):579–584.

Hull J.M., D. Tufts, J.R. Topinka, B.P. May, H.B. Ernest. 2007. Development of 19 microsatellite loci for Swainson’s Hawks (Buteo swainsoni) and other Buteos. Molecular Ecology Notes 7 (2), 346–349.


Read about Swainson's Hawks at the California Department of Fish and Game web sites:
Swainson's Hawk Inventory

Threatened and Endangered birds in California including Swainson's Hawks

Swainson's Hawk information