. The Canadian field-naturalist. Month Month Month 1977 1978 Month Month 1979 II wk. Month Estimated Supporting crust Figure 2. Snow depth under coniferous cover and numberof weeks with more than 50 cm in the Pohenegamook wintering area, 1973 1979. In spite of the general belief that overpopulation is responsible for high winter mortality rates, we do not believe that such is the case for the Pohenegamook wintering area. Browse surveys conducted annually since 1972 indicate that only one stem out of three and one twig out of five were browsed by deer in the coniferous forest type which support
. The Canadian field-naturalist. Month Month Month 1977 1978 Month Month 1979 II wk. Month Estimated Supporting crust Figure 2. Snow depth under coniferous cover and numberof weeks with more than 50 cm in the Pohenegamook wintering area, 1973 1979. In spite of the general belief that overpopulation is responsible for high winter mortality rates, we do not believe that such is the case for the Pohenegamook wintering area. Browse surveys conducted annually since 1972 indicate that only one stem out of three and one twig out of five were browsed by deer in the coniferous forest type which supports the highest deer densities (F. Potvin, unpublished data). This utiliza- tion rate is lower than in many other yards in the province and the browse species comprise mostly Mountain Map\e {Acer spicatum). Beaked Hazelnut (Curyluscornuia), and Balsam Fir, typical of our deer range. These twigs were available in winter because only twigs between 50 and 210 cm from the ground were included in the surveys and most of them were above the 70-cm level. Therefore the quantity of food does not appear to be a limiting factor. Although good quality browse may be abundant in winter, deer will use some of their fat reserves each day, losing 20-30% of their weight during the whole season (Mautz 1974). This is a normal adaptation to compensate for the low digestibility of browse and also to help supply enough energy to face the harsh climatic conditions. A longer winter or difficult snow conditions can exhaust these limited reserves before springtime. Furthermore, a sudden heavy demand caused by rapidly deteriorating climatic conditions (snow storm) or harassment may kill an animal even though its energy reserves are not completely exhausted. This may explain the 11 mortality cases. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original
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