Gaps and Runs in Nest Cavity Occupancy: Cavity “Destroyers” and “Cleaners” Affect Reuse by Secondary Cavity Nesting Vertebrates
Bibliographic record
Abstract
Many animals require tree cavities for breeding and these sites may be reused by a diversity of secondary cavity nesters over a timespan of decades. It is unknown whether the reuse of holes changes their desirability as nest sites. We hypothesized that some species, "cavity destroyers", degraded the quality of holes by filling them with coarse nest material or waste whereas other species, "cavity cleaners", might prolong the use of a hole by removing debris or enlarging the hole. Using data gathered during 22 years from a field study in central British Colombia, we analyzed long-term patterns of cavity occupancy in relation to their sequential use by bird and mammal species, grouped by traits. Patterns of cavity occupancy were variable with 49% of 875 large-sized holes (excavated by northern flickers Colaptes auratus and pileated woodpeckers Dryocopus pileatus) and 19% of 672 smaller-sized holes incorporating runs of sequential use that lasted up to 18 years. But 11-25% of cavities also had gaps of 3-13 years between occupancies. Mammals, raptors and European starlings, consistent with the hypothesis they were cavity destroyers, occupied cavities as terminal users and before gaps more often than expected by chance. The pattern of occupancy by northern flickers was random in relation to gaps or prior use by other species so, although flickers did not target old holes to clean, neither did they avoid them. Small cavities that were renovated by flickers into larger cavities had double the reuse rate. Runs of cavity occupancy that involved only cavity-destroying species were shorter than runs that involved periodic use by flickers, suggesting the woodpecker, through its cleaning and renovation, prolonged the use of such holes.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".