Avian cholera in the central and Mississippi flyways during 1979-1980.

Waterfowl mortality form avian cholera during July 1979-May 1980 was widespread in the Central and Mississippi flyways, occurring in a wide variety of species and locations from nesting grounds of snow geese (Chen caerulescens) on Hudson Bay, south to wintering areas on the Texas coast and playa lakes region. Mortality estimates at the various sites ranged from several birds to 72,000. The chronological and geographic occurrence of outbreaks correspond closely to waterfowl migrations from infected sites, suggesting that waterfowl served to distribute avian cholera along migration routes. Recurrent outbreaks at several locations suggest that these sites have become enzootic for this disease. The magnitude of avian cholera mortality and its geographic spread during 1979-80 underscores the need to address management of this disease on an intra- inter-flyway basis.