Habitat Use and Distribution of a Recently Discovered Population of Humboldt Martens
Bibliographic record
Abstract
The Humboldt marten (Martes caurina humboldtensis) has declined from over 95% of its historic range and currently occurs in just four extant population areas (EPAs). Prior to their listing under the Endangered Species Act, a conservation strategy was developed to identify key conservation needs for this species. This assessment identified an area near the California–Oregon (CA–OR) border as the second EPA in California, yet little was known about the overall distribution or habitat used by this population. This prompted our investigation to provide the first systematic survey of the CA–OR EPA and to assess habitat use using an occupancy modeling framework. Between 2017 and 2018 we surveyed 51 survey units in and adjacent to the EPA and detected martens at 20 units (39.2%). We found that occupancy by martens was most influenced by the amounts of low-elevation late-seral old-growth forest habitat, riparian habitat, and mid-seral forest habitat. The probability of occupancy by martens was greatest in low-elevation (< 800 m, Odds Ratio [OR] = 0.33, 95% Confidence Interval [CI] = 0.13–0.81) habitat and was positively associated with late-seral forest habitat at the 1,170 m home range scale (OR = 35.31, 95% CI = 1.30–958.07), riparian habitat at the 1,170 m home range scale (OR = 3.20, 95% CI = 1.01–10.1), and marginally by mid-seral forest habitat at the 50 m microhabitat scale (OR = 1.28, 95% CI = 0.95–1.73). Our findings identified habitat characteristics important for explaining the distribution of this understudied population, addressing two of the highest priority research needs identified in the Humboldt marten conservation strategy. Key Points Our surveys detected Humboldt martens in areas beyond the previously mapped California–Oregon extant population area, expanding the known distribution. Martens were detected at 20 of 51 (39%) survey units in and adjacent to the California–Oregon extant population area, suggesting a patchy distribution. Occupancy by martens was most influenced by low-elevation late-seral forest and riparian habitat (home range scale).
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".