Abstract

The U.S. Fish and Wildlife Service has received numerous petitions for listing sage-grouse (Centrocercus urophasianus) as a threatened or endangered species. The role of infectious diseases in reduced productivity and population declines in sage-grouse over their range is not known. Information on diseases of sage-grouse is limited. Therefore, to determine if there was a high prevalence of disease in sage-grouse in portions of their range, we surveyed sage-grouse (n=40) from southeastern Oregon in April 2003 for serologic evidence to selected disease agents including: Salmonella typhimurium, S. pullorum, Mycoplasma gallisepticum, M. synoviae, avian influenza, Newcastle disease, Chlamydophila psittaci (n=36), and West Nile virus (n=27). All were negative. We also surveyed the same sage-grouse from southeastern Oregon (n=40) and additional (n=37–38) sage-grouse from northwestern Nevada for serologic evidence of exposure to avian infectious bronchitis virus (AIBV; Arkansas 99, Massachusetts 41, and Connecticut types) using the hemagglutination-inhibition test. Avian infectious bronchitis virus causes early chick mortality in domestic poultry, and we had observed unexplained early sage-grouse chick mortality in southeastern Oregon. We found 46% (36/78) had positive titers (1:16) for AIBV Arkansas 99 type, 8% (6/77) for Massachusetts 41 type, and 53% (20/38) for Connecticut type. During October 2003, attempts to isolate AIBV from Nevada sage-grouse tracheal and cloacal swabs (n=21) by egg-culture and fluorescent antibody techniques were unsuccessful. This is the first known published report that sage-grouse have positive antibody titers to AIBV. The effects AIBV may have on sage-grouse populations are unknown. The importance of surveys for parasites and diseases in sage-grouse cannot be overemphasized. Only with such knowledge can proper management of this dwindling species be accomplished.