Are North American bird species' geographic ranges mainly determined by climate?
Bibliographic record
Abstract
Abstract Aim It is commonly asserted that climate presents the primary constraint on species’ geographic distributions, and that species’ distributions should therefore shift to track changing climate. However, the evidence is surprisingly mixed about the causal link between species’ distributions and climate. Correlations between distributions and climate may be indirect, reflecting influences of other spatially structured habitat variables (e.g., land cover) and/or population processes (e.g., dispersal). Here, we ask if species’ geographic distributions are more strongly related to climate, or to other spatially structured variables. Location The contiguous United States and southern Canada. Time period 1990–2000. Major taxa studied North American passerine birds. Methods We used the breeding‐season distributions of 19 widespread species of passerine birds whose breeding‐season distributions fall entirely within the area sampled by the North American Breeding Bird Survey. We related these distributions to temperature and precipitation, geographic coordinates, and the degree of occupation of neighboring sites by conspecifics. Two spatial scales were examined: the geographic location of species’ ranges within North America, and site occupancy within species' ranges. We examine these relationships using generalized linear models, structural equation modeling, random forest models and spatial correlograms. Results On average, geographic coordinates and a model of neighborhood occupancy outperform a simple climatic model. After controlling for geographic coordinates, species occupancy is poorly related to climate. Neighborhood occupancy accounts for the majority of variance captured by geographic coordinates within ranges, and more for the continental placement of ranges. On average, species’ distributions are more strongly and more directly related to spatial coordinates, and neighborhood occupancy, than to climate. Main conclusions Our results are inconsistent with the hypothesis that climate is the primary, direct determinant of species’ geographic distributions. Rather, other spatially structured factors appear to be stronger determinants of both continental range placement and within‐range distributions of this sample of North American birds.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".