| This is an inquiry into landscape-level population dynamics in the snowshoe hare, Lepus americanus, using empirical field data to test ecological theory. We found evidence supporting a source-sink dynamic, the mechanism proposed to explain why snowshoe hare populations appear not to cycle in fragmented forests of the species southern range. We estimated birth, death, and movement rates for snowshoe hares that lived solely, or in mixtures of, 4 different categories of forest stand structure (FSS) type. We validated the use of ultrasonography as an effective tool to monitor fetal number and pregnancy rate. We sampled individual patterns of FSS type occupancy, which we used as covariates in survival and emigration models. Estimated survival rates decreased as individuals spent proportionally more time in the Open young and Open mature FSS types. The Dense young and Dense mature FSS types were potential “sources.” Dense mature had positive expected population growth, which was lower in models that included movement. Open mature and Open young FSS types were “sinks.” For a model landscape with a simplified model for succession, and where Dense mature forest was prevalent, snowshoe hare populations stayed higher when loss of high-quality patches was asynchronous.; We used an experiment to test for short-term effects of pre-commercial thinning (PCT) on snowshoe hare densities. Compared to control stands, snowshoe hare densities declined after standard prescription (100% of stand area) PCT; and in stands treated with pre-commercial thinning with reserves (PCT-R), where 20% of the total area was retained in uncut ¼ ha patches. Declines were prominent in the second winter after treatment. Snowshoe hares used retained patches more than thinned areas within PCT-R stands. Also, of 49 dead radio-collared snowshoe hare locations, none were in extremely densely vegetated microhabitats.; Predation risk influenced snowshoe hare movement behavior: snowshoe hares' responses to moonlight corresponded to seasonal variation in moonlight intensity. When the moon was more than half full and the ground snow-covered, predation rates were higher and snowshoe hare movement distances were lower than near new moons. Neither predation rate nor movement rate varied when the ground was snow-free. |
