Graduation Date

Fall 2023

Document Type

Thesis

Program

Master of Science degree with a major in Natural Resources, option Wildlife

Committee Chair Name

Micaela Szykman Gunther

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Sean Matthews

Second Committee Member Affiliation

Community Member or Outside Professional

Third Committee Member Name

Ho Yi Wan

Third Committee Member Affiliation

HSU Faculty or Staff

Subject Categories

Wildlife

Abstract

The Humboldt marten (Martes caurina humboldtensis) is a species facing conservation concern in Oregon and California. Historical populations were subjected to unregulated fur trapping and timber harvest throughout the late 19th and early 20th centuries leading to a 90% decline in their distribution. As such, the Humboldt marten is listed as a state endangered species in California, and the analogous ‘coastal marten’ is listed as federally threatened under the Endangered Species Act and classified as a Species of Greatest Conservation Need in Oregon and California. Contemporary populations are small, and isolated, and threatened by habitat loss from timber harvest and wildfires. Martens are also at risk of interspecific competition and intraguild predation. Species conservation and adaptive management efforts require additional information about marten population dynamics, habitat associations and inter-specific interactions. We estimated the abundance and density of Humboldt martens in northern California and subsequently tested the influence of forest conditions and co-occurring carnivores on marten density. We deployed non-invasive hair snares and remote cameras to collect genetic data on individual martens and survey for co-occurring carnivores in northern California. We developed a spatial capture-recapture model to estimate marten abundance and density, and two single species occupancy models to estimate space-use of fishers (Pekania pennanti) and bobcats (Lynx rufus) within our study area. We then fit two post-hoc generalized linear models to evaluate the influence of 1) forest and climate conditions and 2) fisher and bobcat space-use on marten density. We found that marten density was positively correlated with snowpack and forest stand diversity, and negatively correlated with fisher and bobcat use and ladder fuel density. Our results suggest that Humboldt martens persist in forest patches with high structural diversity and more snow, and areas with lower risk of competition and intraguild predation. We suggest future research focus on the effects of landscape disturbance that results in a loss of structural diversity along with the additive effects of interspecific competition to better understand Humboldt marten persistence.

Citation Style

Journal of Wildlife Management

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