The ecology of snowshoe hares in northern boreal forests [Chapter 6]
| Authors: | Karen E. Hodges |
| Year: | 1999 |
| Type: | General Technical Report |
| Station: | Rocky Mountain Research Station |
| Source: | In: Ruggiero, Leonard F.; Aubry, Keith B.; Buskirk, Steven W.; Koehler, Gary M.; Krebs, Charles J.; McKelvey, Kevin S.; Squires, John R. Ecology and conservation of lynx in the United States. Gen. Tech. Rep. RMRS-GTR-30WWW. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 117-162. |
Abstract
Snowshoe hares exhibit eight to 11 year population fluctuations across boreal North America, typically with an amplitude of 10 to 25 fold. These fluctuations are synchronous across the continent, with the most recent peak densities occurring in 1990 and 1991. The numeric cycle is driven by changes in survival and reproduction, with annual survival of adults ranging from approximately five to 30% and annual natality ranging from approximately six to 20 leverets/female. These parameters show cyclic changes because of functional and numerical responses of predators and changes in food supply. Predator densities show approximately two to 10 fold fluctuations during the hare cycle. The cyclicity of hares may be partly explained by regular behavioral shifts, with repercussions on their physiology, availability to predators, reproduction, and survival. However, this hypothesis needs more empirical support before it can be accepted.