Treesearch

Disturbance dynamics differ in the three subregions of the North American boreal forest (taiga, western United States, and eastern United States) where lynx are found, resulting in a range of potential effects on lynx populations. Fire severity tends to be high in most of the forest types where lynx habitat occurs, although subsequent succession will differ among the subregions. Other disturbance dynamics involve insects, disease, wind, and human ownership and use, such as logging, mining, agriculture, and fire suppression. The author addresses three general lynx management implications...

Habitat fragmentation and interspecific competition are two important forces that potentially affect lynx populations. Fragmentation operates by various mechanisms, including direct habitat loss, vehicle collisions and behavioral disturbance from roads, and changes in landscape features such as edges. Competition takes two forms: Exploitation competition involves potential competitors, such as coyotes and raptors, for food with lynx. Interference competition involves aggressive acts, almost always by a larger animal, that can include attacking and killing. Habitat fragmentation tends to...

In conservation planning, the importance of natural variation is often given inadequate consideration. However, ignoring the implications of variation within species may result in conservation strategies that jeopardize, rather than conserve, target species (see Grieg 1979; Turcek 1951; Storfer 1999). Natural variation in the traits of individuals and populations is the product of the genetic composition of the individual and the environment to which the individual is exposed. Inherited traits are those that are largely genetically determined, whereas non-inherited traits result primarily...

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....

Snowshoe hares occur in many of the montane and sub-boreal forests of the continental United States, as well as throughout the boreal forests of Canada and Alaska. Population dynamics in their southern range were previously thought to be noncyclic, in contrast to the strong 10-year fluctuation that typifies boreal populations of snowshoe hares. Time series data and studies of hare demography indicate that northern and southern populations of hares may instead have similar population dynamics. Hares in southern areas appear to experience two- to 25-fold fluctuations in numbers with peaks...

Using written accounts, trapping records, and spatially referenced occurrence data, the authors reconstructed the history and distribution of lynx in the contiguous United States from the 1800s to the present. Records show lynx occurrence in 24 states. Data over broad scales of space and time show lynx distribution relative to topography and vegetation. For all three study regions (Northeastern states, Great Lakes and North-Central states, and Western Mountain states), high frequencies of occurrence were in cool, coniferous forests, with occurrences at primarily higher elevations in the West.

We review the ecology of lynx in the northern part of its range, drawing heavily on the results of recent research from that region. Snowshoe hares form the bulk of prey items in essentially all studies and at all periods in the cycle, but use of alternative prey, often red squirrel, increases as hares become scarce. Caching of freshly killed prey is rare, although carrion is consumed, primarily during periods of food shortage. Habitat use by lynx varies geographically, but tends to track that of snowshoe hares. Lynx prefer older (>20 years old) regenerating forest stands. Mature forest...

We examined habitat selection by 22 lynx on the Okanogan National Forest in Washington, analyzing radio-telemetry data collected during two previous studies, 1981 through 1988. At a coarse scale, lynx showed little use of areas below 1,400 m or above 2,150 m. Within the zone between 1,400 and 2,150 m, lynx used areas with slopes <10% and moderate stream densities in winter. Selection for combinations of physical variables and vegetation types was stronger in winter versus summer, and lynx showed strong selection for lodgepole pine cover types in winter. Relative abundance of snowshoe hares...

When we began the task of elucidating the scientific basis for lynx conservation in June 1998, I had little idea how constrained our time would be. The request to do this job came from a consortium of federal land management agencies in response to the U.S. Fish and Wildlife Service’s "proposed rule" to list the Canada lynx as a threatened or endangered species throughout its range in the contiguous United States. I underestimated the extent to which legal mandates and the expectations of information-hungry biologists and decision-makers would push us. By late February 1999 we had provided...

On April 2, 1993, the incumbent U.S. President traveled to Portland, Oregon, to intervene in a national political crisis engendered by public concern over the conservation of native wildlife on public lands. Environmentalists had successfully used existing statutes, most notably the National Forest Management Act and pursuant regulations, to shut down timber industry operations on commercially important federal lands in the Pacific Northwest. Widespread economic dislocations were expected, and the federal courts showed no signs of reversing the decision to suspend timber-harvesting...