Long-term databases track changes in the population parameters of the top predator (gyrfalcon) and the keystone prey (willow ptarmigan).
Three study areas spaced north to south across the Yukon are surveyed annually. Breeding density and productivity are key variables along with breeding chronology. Ground search in late winter is used to survey ptarmigan, while air survey to known nest sites tracks gyrfalcon numbers.
Ongoing reports and publications cover significant details and trends. Currently evidence points to a disruption to normal population cycling, and suggests a declining overall trophic response in the system.
This project is a part of the Biodiversity Monitoring Program with the Yukon Research Centre.
2008. Willow and Rock Ptarmigan Density Estimates – Northern Yukon 1975- 2008. IPY Project Report (W.O.L.V.E.S.), Northern Research Institute ms., Yukon College.
- Mossop, D.H. 2014. Biodiversity assessment and monitoring research - a summary report of activities. Yukon Research Centre, 13 p.
- Mossop, D.H. 2015. Biodiversity assessment and monitoring research - a summary report of activities. Yukon Research Centre, 12 p.
- Barichello, Norman and Mossop, Dave. 2011. The overwhelming influence of ptarmigan abundance on gyrfalcon reproductive success in the central Yukon, Canada. Northern Research Institute, 16 p.
- Mossop, D. H. 2011. Long-term studies of Willow Ptarmigan and Gyrfalcon in the Yukon Territory: A collapsing 10-year cycle and its apparent effect on the top predator. In R. T. Watson, T. J. Cade, M. Fuller, G. Hunt, and E. Potapov (Eds.). Gyrfalcons and Ptarmigan in a Changing World. The Peregrine Fund, Boise, Idaho, USA. http://dx.doi.org/10.4080/gpcw.2011.0206