A Survey of the Choanal and Cloacal Aerobic Bacterial Flora in Free-Living and Captive Red-Tailed Hawks (Buteo jamaicensis) and Cooper's Hawks (Accipiter cooperii)

Abstract

The normal flora of free-living red-tailed hawks (Buteo jamaicensis) and Cooper's hawks (Accipiter cooperii) has not been well described. We trapped and banded 10 free-living red-tailed hawks and 10 free-living Cooper's hawks during the 1992 fall migration in Marin County, CA, USA. Three choanal and 3 cloacal swabs were collected from each bird to characterize the aerobic bacterial flora. Cloacal swabs were obtained from an additional 24 free-living birds, 13 red-tailed hawks and 11 Cooper's hawks, specifically for isolation of Salmonella species. Moreover, 3 choanal and 3 cloacal swabs were collected for comparison from 7 captive red-tailed hawks and 3 captive Cooper's hawks. Coagulase-negative Staphylococcus/Micrococcus species and Corynebacterium species were the most frequent choanal isolates from both free-living and captive red-tailed hawks as well as from free-living Cooper's hawks, while Corynebacterium and Pasteurella species were the most frequent choanal isolates from captive Cooper's hawks. The most frequent cloacal isolates of both free-living and captive red-tailed hawks were coagulase-negative Staphylococcus/Micrococcus species and Streptococcus species; those from free-living Cooper's hawks were coagulase-negative Staphylococcus/Micrococcus species and Escherichia species; and those from captive Cooper's hawks were Escherichia species, coagulase-positive Staphylococcus species, and Streptococcus species. Escherichia species were not isolated from the choana of free-living birds, while Pasteurella species were not isolated from the cloaca of any birds. Corynebacterium species and Bacillus species were isolated from the cloaca of free-living red-tailed hawks and Cooper's hawks but not from captive birds. Salmonella species were isolated from the cloaca of free-living birds of both species but not from captive birds. Although primary bacterial infections are not a common cause of disease in raptors, an understanding of normal microbial flora may help in interpreting the significance of bacterial isolates in ill birds.