Older is Better: Beaver Ponds on Boreal Streams as Breeding Habitat for the Wood Frog
Bibliographic record
Abstract
Succession of stream ponds mediated by beaver (Castor canadensis) damming and foraging in riparian zones may contribute to changes in amphibian populations. Our study examined the use of beaver ponds by the wood frog (Rana sylvatica) in a network of boreal streams in west-central Alberta, Canada. We quantified relations between breeding populations of wood frogs estimated from call surveys and pond age and riparian canopy cover, and we compared an index of juvenile recruitment to metamorphosis estimated with pitfall trap captures between new (<10 yr) and old (>25 yr) beaver ponds. We also conducted an in-pond enclosure experiment to determine if differences in physicochemical conditions of new versus old ponds influenced larval performance. Regression and Akaike's Information Criterion model averaging indicated that both density and calling intensity of male wood frogs at beaver ponds had a negative relationship with percent riparian canopy cover and had a positive relationship with pond age. The best a priori statistical models, however, included riparian canopy cover rather than pond age as a significant covariate. Old ponds had reduced riparian canopy and greater abundance of submergent vegetation, thermal degree-days, and dissolved oxygen concentrations compared to newly formed ponds. While survival of larval wood frogs in enclosures did not differ between pond age classes, growth and development rates in old ponds were greater than in new ponds. In addition to warmer water in old ponds, results from a laboratory experiment suggest that higher concentrations of dissolved oxygen characteristic of old ponds can enhance larval growth rates. Older beaver ponds may support more breeding wood frogs due to adult selection for open-canopy ponds and the associated larval environments favourable for high rates of juvenile recruitment. Forest management that protects beaver and their food supplies may also promote healthy populations of boreal amphibians.
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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 | 0.000 |
| 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) | 0.000 | 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".