A fine‐scale U.S. population estimate of a montane spruce–fir bird species of conservation concern
Bibliographic record
Abstract
Abstract Bicknell's Thrush ( Catharus bicknelli ) is one of the most range‐restricted bird species in North America. In the United States (U.S.), it occurs only in the disturbed montane forests of fir ( Abies balsamea ) and spruce ( Picea spp.) in the northeastern states of New York, Vermont, New Hampshire, and Maine. Climate change is expected to substantially diminish this vegetation community (>50% extinction from current range) by 2300. Despite the increasingly tenuous conservation status of the species, fundamental demographic parameters remain unknown and overall population size is uncertain. We used N‐mixture models in a hierarchical Bayesian framework to predict population size and to elucidate spatial and temporal patterns of Bicknell's Thrush abundance in the northeastern United States. From 2011 to 2016, as part of Mountain Birdwatch, citizen‐scientists conducted 14,552 five‐minute point counts at 747 sampling locations along hiking trails. Observers detected Bicknell's Thrush at 49.4% of points and tallied 1079 observations of the species. Bicknell's Thrush abundance was parsimoniously modeled as a complex function of elevation, forest canopy cover, and latitude. Using our model results, and the estimated U.S. range of the Bicknell's Thrush, we produced the first fine‐scale (<1.0 ha resolution) abundance estimate and map of Bicknell's Thrush density across their U.S. range. We predicted the U.S. Bicknell's Thrush population in 2016 as 71,318 (95% credible interval: 56,080–89,748), and 95% of that population occurred above 805 m. Combining our results with existing estimates of population size in Canada suggests a global population size of <120,000; Bicknell's Thrush likely have one of the smallest population sizes of regularly occurring bird species within the contiguous United States and Canada. By cross‐referencing the U.S. Geological Survey Protected Areas Database, we estimated that 76.6% of Bicknell's Thrush habitat occurred on conserved lands across the United States and that this habitat supported 84.6% of the predicted population. The White Mountain National Forest (New Hampshire and Maine) is the largest conservator of Bicknell's Thrush habitat in the United States and supports ~31% of the predicted U.S. population. Our model provides a testable framework for assessing the success of future conservation and management actions on Bicknell's Thrush populations throughout their U.S. range.
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 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) | 0.069 | 0.001 |
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".