Serum samples were obtained from 307 birds collected on a sheep range (Hopland Field Station) in northern California. Forty (13%) of these birds had agglutinating antibodies to Coxiella burnetii. At a nearby dairy farm, sera from 49 of 129 (38%) birds tested were positive for Q fever antibodies. In both areas the birds with the highest antibody prevalence were the carrion eating birds (crows, ravens and turkeyvultures) and those birds (Brewer's and red-winged blackbirds, golden-crowned sparrows and pigeons) that live and feed in close proximity to infected livestock. The extent to which migratory birds are involved in the ecology of this zoonosis is uncertain. Immigrant birds may have been exposed to Q fever prior to their arrival in the area; however, emigrating birds have the potential to disperse the rickettsiae from such areas where livestock are infected with C. burnetii.