Date of Award:

2003

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Ecology

Department name when degree awarded

Forest, Range, and Wildlife Sciences

Advisor/Chair:

John A. Bissonette

Abstract

The "Den Mother" marten habitat quality models were created to provide insight into American marten habitat selection behavior and to promote the recovery of the Newfoundland marten (Martes americana atrata) population. Although these objectives are typical of most wildlife habitat modeling projects, the marten's idiosyncratic habitat ecology and apparently intractable conflicts associated with timber harvesting motivated a unique, process-oriented approach to appraising landscapes. The Den Mother models used optimal decision-making principles to synthesize critical resources (den sites and foraging opportunities) and constraints (adverse thermal situations and exposure to predations) into a single hierarchical framework. The resulting spatially explicit, combinatorial optimization models depend on a complex array of interacting assumptions. However, in mechanistic models, explicit assumptions provide the means by which insights are gained. For example, manipulating prey population parameters provided a clear demonstration of how resource conditions confound the relationship between landscape configuration and marten fitness, thereby challenging conventional definitions of habitat based on vegetation alone. Likewise, the models' sensitivity to spatial circumstances argued against the concept of an "optimal landscape," a traditional objective for wildlife habitat analyses. Although the model analyses did not refute the conventional wisdom that marten are strongly associated with (and may depend on) large contiguous blocks of senescing and defoliated forests, they did suggest that the marten is an opening-sensitive, rather than coresensitive, species. The models also suggested new avenues for research addressing marten den site selection, predator avoidance behavior, foraging efficiency, and space use strategies, as well as new techniques for assessing the trade-offs that govern marten habitat selection behavior. Finally, the models also suggested new guidelines for promoting marten recovery in an adaptive management context, including recommendations for placing artificial resting structures; creating favorable landscape mosaics; managing ephemeral resources such as transition old-growth forests, defoliation, and coarse woody debris; and developing alternative, competing management scenarios that address both forest and prey conditions simultaneously.

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