General Technical Report (GTR)
Canada lynx occur throughout boreal forests of North America, but ecological conditions in southern regions differ in many respects from those in Canada and Alaska. To evaluate the extent to which lynx ecology and population biology may differ between these regions, we review existing information from southern boreal forests and compare our findings to information presented in Chapter 9 on lynx in the taiga. Throughout North America, lynx diets in both winter and summer are dominated by snowshoe hares. In southern boreal forests, alternative prey, especially red squirrels, are important constituents of the diet. This reliance on alternative prey may reflect a response to low-density hare populations in southern regions, because alternative prey are also important in the taiga during lows in the snowshoe hare cycle. In addition, limited information on lynx diets during snow-free months indicates that alternative prey are important during summer in both northern and southern populations, regardless of the status of local hare populations. As in the taiga, lynx in southern regions are associated with boreal and sub-boreal forest conditions, including upper elevation, coniferous forests in the western mountains and mixed coniferous-deciduous forests in the Northeast. Throughout their range, lynx are absent or uncommon in dense, wet forests along the Pacific coast. In both northern and southern regions, lynx occur predominantly in habitats where snowshoe hares are abundant, especially early successional stands with high stem densities. However, in southern boreal forests, such habitats appear to be used primarily for hunting; all known den sites in southern regions were located in mature forest stands with large woody debris. As in the taiga during times of hare scarcity, relatively large home ranges appear to be characteristic of lynx in southern boreal forests. Lynx dispersal movements are similar to those reported from the taiga. However, only lynx in southern forests are known to make exploratory movements prior to dispersal. We speculate that such explorations may reflect a more heterogeneous habitat mosaic, and a correspondingly lower probability of successful dispersal in southern regions. Demographic characteristics of southern lynx populations, including low densities, low pregnancy rates, low litter sizes, and high kitten mortality rates are similar to those reported from the taiga during times of hare scarcity. As in the taiga, we found little evidence that roads represented a significant disturbance or mortality factor for lynx. Roads into lynx habitat may, however, provide access to generalist competitors, such as coyotes and bobcats. Although there is little evidence that competition with other predators negatively influences lynx populations, this aspect of their ecology has not been studied in southern boreal forests. In summary, differences in lynx ecology between populations in southern boreal forests and those in the taiga appear to be related primarily to the use of alternative prey species; the effect of habitat patchiness on movements, reproduction, and survival; and the potential effects of different communities of predators and competitors on lynx populations.