BREEDING SUCCESS OF TREE SWALLOWS ALONG A GRADIENT OF AGRICULTURAL INTENSIFICATION
Bibliographic record
Abstract
The intensification of agricultural practices has been identified as the main cause of population decline in farmland birds since the 1960s in both Europe and North America. Although the links between species richness or abundance and various components of agricultural intensification are well established, the mechanisms underlying these trends have rarely been addressed along a gradient of intensification or have been quantified at only one spatial scale. Here we quantified the influence of landscape structure on the nest box occupancy and breeding success of Tree Swallows (Tachycineta bicolor) at seven spatial scales (1, 2, 3, 4, 5, 10, and 20 km radii) over a 10 200-km2 gradient of agricultural intensification in southern Québec, Canada. A network of 400 nest boxes distributed among 40 farms was visited every two days over three breeding seasons, 2004-2006. Nest box occupancy decreased with the proportion of intensive cultures (maize, cereals, and soybeans) in the landscape, especially when manure heaps and tanks were abundant, and was also determined by local variables (i.e., nest box clearance, interspecific competition) and by previous-year fledging success. Clutch size decreased as the breeding season progressed and with the proportion of intensive cultures in the landscape, with no consistent variation across spatial scales. Hatching success was not related to any landscape variables but increased with clutch size. Both the number of fledglings and fledging probability increased with the proportion of extensive cultures (hayfields, pastures, and fallows). These effects increased with spatial scale and reached a plateau at the 5 km radius: the maximum distance from the nest reached by foraging Tree Swallows. Our results can likely be attributed to lower food availability in intensive cultures compared to extensive ones. This study suggests that several components of breeding that impact on population structure and dynamics of insectivorous birds will be negatively affected by agricultural intensification.
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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) | 0.001 | 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 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".