Effects of predation on the population dynamics of lemmings and on loss of goose nests
Bibliographic record
Abstract
Collared lemmings (Dicrostonyx groenlandicus) fluctuate periodically in abundance on the Kent Peninsula, Northwest Territories, Canada. I tested whether predation was necessary to (1) limit the lemming population during a peak and decline summer (1996 and 1997), and (2) cause the population decline. The nesting success of geese also fluctuates at this location. I tested whether the relative number of goose nests lost could be predicted from functional and numerical responses of nest predators to lemming density. I reduced predation on lemmings with a fence and an overhead mesh of monofilament line over 11 ha, completed during the lemming increase (summer 1995). I used mark-recapture and radio-telemetry to investigate demography in this "Exclosure" and three Control areas, and estimated winter predation from droppings and abundance of predators. Density increased in Exclosure relative to Controls in both summers. Survival was significantly higher within Exclosure during the lemming decline only. Neither proportions of reproductive animals nor net movements differed significantly between treatments. I conclude that predation was a necessary limiting factor in the peak and decline summers, but that the magnitude of limitation was greater in the decline. Density declined over winter on all sites. The next summer (1997), the decline accelerated on controls but was reversed within Exclosure. Summer survival was lower in the decline than in the peak. Lemmings stopped reproducing early in the peak summer. If there was no winter breeding, winter survival was high. The contribution of predation to the winter decline depends on the extent to which mortality factors were compensatory. I conclude that predation may not have been necessary to cause the decline; instead the decline was initiated by cessation of reproduction. However, predation accelerated and extended the decline the next summer. From observed responses of nest predators to lemming density, I predicted that the number of goose nests depredated should be lowest during lemming peaks. This was not true in past lemming cycles in this region (1989 - 1994). I conclude that nest loss cannot be predicted from the phase of the lemming cycle alone, and make testable predictions of how other factors should affect nest loss.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 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".