Spatio-temporal overlap between Yellowstone bison and elk – implications of wolf restoration and other factors for brucellosis transmission risk
Article first published online: 15 FEB 2010
© 2010 The Authors. Journal compilation © 2010 British Ecological Society
Journal of Applied Ecology
Volume 47, Issue 2, pages 281–289, April 2010
How to Cite
Proffitt, K. M., White, P. J. and Garrott, R. A. (2010), Spatio-temporal overlap between Yellowstone bison and elk – implications of wolf restoration and other factors for brucellosis transmission risk. Journal of Applied Ecology, 47: 281–289. doi: 10.1111/j.1365-2664.2010.01770.x
- Issue published online: 8 MAR 2010
- Article first published online: 15 FEB 2010
- Received 26 April 2009; accepted 11 January 2010 Handling Editor: Mark Hebblewhite
- Brucella abortus;
- interspecific transmission;
1. In the Greater Yellowstone Ecosystem, bison Bison bison and elk Cervus canadensis nelsoni act as hosts for Brucella abortus. The presence of B. abortus within wildlife populations is an important conservation issue because of the risk of brucellosis transmission from wildlife to cattle.
2. We investigated conditions facilitating contact between bison (40–60% seroprevalence) and elk on a shared winter range in the Madison headwaters area of Yellowstone National Park. We evaluated the effects of snow pack, season, elk and bison population sizes, and wolf Canis lupus predation risk on the degree of spatial overlap between bison and elk from 1991 to 2006.
3. Sixty-eight per cent of 10 093 independent elk observations occurred within the known bison wintering range, 29% occurred within the distribution of bison within the winter range at the time of sampling and 14% occurred within 100 m of bison. Spatial overlap between bison and elk measured across these three spatial scales increased with week of the season, snow pack, and on days when wolves were within the same drainage area as elk, but decreased with cumulative levels of wolf predation risk.
4. Wolves contributed to immediate, short-term responses by elk that increased spatial overlap with bison, but longer-term responses to wolves resulted in elk distributions that reduced spatial overlap with bison. Spatial overlap increased through the winter and peaked when late-term abortion events and parturition occurred for bison.
5. Synthesis and applications. Despite this high level of association, elk exposure to B. abortus in the Madison headwaters (2–4%) was similar to those in free-ranging elk populations that do not intermingle with bison (1–3%), suggesting that B. abortus transmission from bison-to-elk under natural conditions is rare. Our results suggest that risk-driven elk behavioural responses to wolves are unlikely to have important disease implications. Management of brucellosis in greater yellow stone ecosystem elk populations should focus on reducing elk-to-elk transmission risk and, wherever possible, curtailing practices that increase elk density and group sizes during the potential abortion period.