"Our results suggest that conservation action to protect even the smallest populations of Ethiopian wolves from rabies is both worthwhile and urgent," say Daniel Haydon of the University of Guelph in Ontario, Canada; Karen Laurenson of the University of Edinburgh in Roslin, UK; and Claudio Sillero of Oxford University, UK, in the October issue of Conservation Biology.
Ethiopian wolves are restricted to seven isolated montane populations, one with about 250 and the rest with roughly 20-80 wolves. Each population is surrounded by domestic dogs that carry rabies, and evidence suggests that when a wolf gets rabies, the disease spreads to about 90% of its pack. In the early 1990s, a rabies outbreak cut the largest Ethiopian wolf population by two-thirds. This population (Bale Mountain) has recovered, thanks to a dog vaccination program that began there in 1996.
To see if disease management would also benefit the other Ethiopian wolf populations, Haydon and his colleagues used a model that accounted for factors including the level of rabies incidence in the dog population and the wolves' habitat sizes (from 25-250 km2, which is the range of habitat sizes of the remaining wolf populations). The model predicted the likelihood that a given population would survive for the next 50 years.
Haydon and his colleagues found that when there was no rabies, all the wolf populations were fairly stable -- even those as small as 25-50 and in the smallest habitat patches. However, at current rabies levels, all the wolf populations were more likely to become extinct. Notably, the likelihood of extinction rose to 28% in 50 km2 patches and to 46% in 25 km2 patches. "Disease appears to be a significant threat to these smaller population
Contact: Karen Laurenson
Society for Conservation Biology