Principal Investigator:		John A. Bissonette USGS Biological Resources Division, Utah Cooperative Research Unit Department of Fisheries and Wildlife, Utah State University
Graduate Research Assistant:		William A. Adair Department of Fisheries and Wildlife, Utah State University Ph.D. Wildlife Ecology (in progress)

Because of the perceived threat posed by extensive timber harvesting, the Newfoundland subspecies of the American marten (Martes americana atrata) has been listed as endangered according to COSEWIC (Committee On the Status of Endangered Wildlife in Canada) guidelines. The RENEW (Recovery of Nationally Endangered Wildlife) Recovery Plan for the Newfoundland marten includes a comprehensive habitat assessment model capable of forecasting marten population response to landscape change, with particular emphasis on the impacts generated by timber harvesting. The Western Newfoundland Model Forest (WNMF), a formal collaboration among federal and provincial agencies and private groups, was also created (in part) to help resolve potential conflicts between marten and fiber production. The model described here is intended to be used by the WNMF and cooperating agencies as a tool for understanding marten habitat dynamics and for optimizing timber harvest design.

Four criteria seem to describe landscape quality for Newfoundland martens: 1) Voles, hares, and other food sources should be abundant and accessible. Large-diameter downed woody debris provides access to the subnivean small mammal prey and is apparently a critical component of winter habitat. 2) Secure, thermally favorable resting structures, including deadfalls and large-diameter standing snags, must be present. 3) Overhead canopy cover and large-diameter tree boles provide security from aerial predators and a means for escaping terrestrial predators. In Newfoundland, marten very rarely venture far from wooded cover. 4) American marten are ``thermally challenged,'' expending considerable metabolic energy just to maintain thermal homeostasis. Marten appear to select structural conditions that provide the best available protection from wind and cold temperatures.

These four criteria have been incorporated into a unique mechanistic model that may be capable of forecasting marten population distribution. This model assesses landscape conditions from the perspective of lactating females with kits, who conform to classical central-place foraging theory and are especially sensitive to the spatial configuration of all four landscape criteria. The model evaluates foraging opportunities according to their abundance and connectedness to the den site, while the den sites are evaluated according to the quantity and quality of the foraging opportunities available. Population distribution is simulated through a pre-emptive territory model based on den site quality. This mechanistic approach was chosen because forecasting population viability in novel landscapes depends on a quantitative link between habitat quality and population productivity. Conventional habitat assessment models (i.e., HSIs) can forecast changing habitat patterns but are by definition unable to forecast population distribution, and hence population viability.

This project's central hypothesis is that mechanistic models are better suited to predicting Newfoundland marten population distribution than conventional wildlife-habitat models. Both mechanistic and conventional models of increasing complexity will be applied to the portion of Newfoundland for which the WNMF has developed long-term telemetry-based home range data (37 animals). These models will be based on the four habitat selection criteria described above. Forecasting power will be evaluated using a Bayesian technique, with total population, population productivity, and spatial accuracy as the criteria for evaluating model success.

Because all of the models depend on understanding the relationship between the four selection criteria and landscape configuration, the structural conditions governing food abundance and accessibility, thermal conditions, resting sites and dens, and traveling patterns were field-evaluated in western Newfoundland. Thermal conditions have been evaluated using laboratory metabolism trials and simple operative temperature recording devices distributed across the major forest communities. Small mammal population distribution, trend, and accessibility were evaluated with 48 live-trapping grids over 4 years (70,000 trap-nights). A total of 52 resting structures and 2 den sites were located for 14 marten collared by the WMNF cooperators, including the Newfoundland and Labrador Wildlife Division and Natural Resources Canada. These data provided the parameters needed to develop the mechanistic and conventional models; long-term telemetry data maintained by the Newfoundland and Labrador Wildlife Division and Natural Resources Canada will be used to assess model success.