Evaluation of predator numerical responses

We evaluated hypotheses of the dynamics of predators ( lynx) relative to prey ( snowshoe hares) and predator abundance in the Yukon, Canada. The hypotheses were that predator ( lynx) dynamics are influenced by prey density, or by both prey and predator densities. Annual lynx population growth rate ( r), estimated from lynx counts, was positively related to previous hare density and negatively related to previous lynx density, as described by the best-fitting additive model ( R-2 = 0.85). Annual lynx growth rate ( r) estimated from lynx tracks was positively related to the ratio of hares per lynx in the best-fitting model ( R-2 = 0.55). There was most support for the prey- and predator-dependent hypothesis of predator dynamics. Projected lynx tracks showed similar trends to observed abundance but lagged one year, emphasising the need for evaluation of projected predator trends.