Pinyon-juniper specialist birds are resilient to local-scale reduction of canopy cover and pinyon pines, but amount of understory shrub cover determines the composition of the insectivore guild
Bibliographic record
Abstract
Drought-induced tree die-off and die-back in the southwestern United States is changing the structure and floristic composition of pinyon-juniper woodlands, a widespread middle-elevation community with high bird endemism. Amid increasing prevalence of high-severity wildfires in this habitat, managers have also turned to mechanical thinning to reduce fuel loads. Therefore, in this study, we asked how breeding-season bird densities are associated with microhabitat-scale structural features and floristic composition in pinyon-juniper woodlands, features likely to change with die-back and mechanical thinning. We fit Bayesian N-mixture models to eight years of monitoring data at three Colorado Plateau national parks and found supported responses to microhabitat variables across 18 of 25 species, though park-level effects were an order of magnitude larger than microhabitat effects. Pinyon-juniper specialists were resilient to loss of canopy cover at local scales, but generalist forest species showed supported associations with greater canopy cover. We found no threshold values of canopy cover, but nine species showed a supported negative effect of park on density at Bandelier National Monument after a large-scale (> 95%) pinyon pine die-off and associated reduction in canopy cover (< 15% remaining). Species also showed weak or no associations with pinyon-pine basal area, perhaps indicating a selection for both junipers and pinyons. Exceptions included positive associations of cavity-nesting birds with greater pinyon-pine basal area, and negative associations of species associated with canopy gaps. The extent of shrub foliage cover, which may increase in woodlands following thinning or die-off, shaped the composition of the insectivorous bird guild. Foliage-gleaning birds of both canopy and understory showed positive supported associations with increasing shrub cover, while aerial insectivore and bark forager densities were negatively affected. An ordination of species’ responses to all covariates suggests the community segregated along a woodland successional gradient and was generally associated with a simplified vertical vegetation structure.
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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".