americanus), and grizzly bear (Ursus arctos); one seroreactive black bear (Ursus americanus) was found (Barmore 1968). Brucellosis recently was detected in black bear and grizzly bear in the greater Yellowstone ecosystem (K. Aune, Mont. Fish, Wildlife, and Parks, pers. commun., 1997). The extent of infection in bear is not known, but bear are unlikely to play a major role in the persistence of brucellosis in YNP (see Part II, "Transmission Among and Between Species").
Mule deer outside YNP have been shown to be seropositive, but deer in YNP have not been shown to carry B. abortus, and it is widely assumed that deer are not a major host for it. Brucellosis has not been detected in Montana in mule deer or white-tailed deer (O. virginianus).