Geographic variation in population cycles of Canadian muskrats (<i>Ondatra zibethicus</i>)
Bibliographic record
Abstract
We investigated the dynamic properties of population cycles in Canadian muskrats (Ondatra zibethicus). Ninety-one historic time series of muskrat-harvest data obtained from the Hudson's Bay Company Archives were analyzed. Most series were 25 years in length (19251949) and were distributed primarily throughout five ecozones. For each series, we estimated period length and coefficients for a second-order autoregressive model. Estimated period length varied between 3 and 13 years, with 3- to 5-year periods located in Subarctic-Arctic ecozones. We hypothesize that the 4-year cycles are largely a result of predation by red fox (Vulpes vulpes), which exhibit 4-year cycles in Arctic regions. The remaining ecozones generally averaged 89 years in period length. However, the relative contributions of direct and delayed density dependence varied along a latitudinal gradient. We hypothesize that both social and trophic interactions are necessary to produce the observed dynamics, but that shifts in the nature of mink predation were responsible for the changes in the relative contribution of direct and delayed density dependence. Essentially, there is a tension between population-intrinsic and trophic interactions that may bound the length of the cycle.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".