Lepus americanus





Lepus americanus

Lepus americanus (snowshoe hare) belongs to the Phylum: Chordata, Class: Vertebrata, and Order: Mammalia. Lepus americanus is common to the northern boreal forests of North America extending south into higher elevations of the Rocky and Appalachian Mountains. It\'s main diet consists of plant shrubs in summer and in winter forage on ground vegetation by digging feeding craters into the ground (Gilbert, 1990).

Experiments conducted by Krebs et al. (1986), set out to determine responses of Lepus americanus to extra natural food supplemented during 1981 to 1984 in the period of a decline phase during the ten-year cycle. It is not known if decline phase is driven by winter food shortage. The experiment consisted of, one experimental and two control grids set up to determine differences between survival, growth, and reproduction in areas supplied with freshly cut white spruce (Picea glauca) and aspen (Populus tremuloides). Similar trends were obtained in all three areas: population size, survivorship, reproduction and growth. Between critical winters of 1981-1982 the experimental grid area lost 77% of its population as compared to 79% and 96% loss for the control grids. Determining the survival rates, the authors used mark-recapture techniques, it was found that probabilities for survivorship in experimental grid (0.79+0.10) were similar to that of control grids (0.71+0.07; 0.56+0.07). Results yielded that extra food intake and cover provided from branches may have not been helpful in increasing survivorship. No differences were measured in reproduction of percentage in adult females caught lactating between control and experimental grids. Based on experiments conducted by Keith and Windberg (1978), we should expect reduced weight loss during the winter months if natural feeding was effective in experimental grid. Results gathered based on growth rates and size yield a reduced weight loss on experimental grid in 1981-1982 (Experimental: -0.04+0.13; Controls: -0.28+0.07 & -0.11+0.30). Such data is not significant to rule that supplemented food is effective.
There is no indication to that decline phase of ten-year cycle is driven by winter food shortage. Extra food intake may not be responsible for higher growth and survival among Lepus americanus according to yielded results.
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References
Gilbert, B. S. 1990. Use of winter feeding craters by snowshoe hares. Canadian Journal of Zoology, 68:1600-1602.

Keith, L. B. and Windberg, L. A. 1978. A demographic analysis of the snowshoe hare cycle. Wildlife Monogr, 58:1-70.

Krebs, C. J., Boutin, S. and Gilbert, B. S. 1986. A natural feeding experiment on a declining snowshoe hare (Lepus americanus) population. Oecologia, 70:194-197.






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