Joint effects of inverse density-dependence and extreme environmental variation on the viability of a social bird species
Bibliographic record
Abstract
Environmental stochasticity and density-dependence can have critical synergetic effects on population dynamics, especially when dealing with threatened species. In this study, we examine the effects of these interactions on the dynamics of a vulnerable bird species, the Dalmatian pelican (Pelicanus crispus). We conducted demographic analysis and population dynamics modelling of the Amvrakikos pelican population (western Greece) based on a 20-y dataset. Results indicated that annual juvenile survival probability is low (mean = 0.65) and varies according to both negative (regulation) and positive (Allee effect) density-dependent processes. In contrast, adult survival is relatively high (mean = 0.95) and less variable. Deterministic and stochastic population dynamics models based on means, inter-annual variances, and covariances between vital rates revealed that the population is increasing deterministically. Simulations of the extinction risk for the study population and also for various population sizes revealed that short-term extinction risk remains extremely low, even for very small populations of the species. However, when we considered the possibility of rare catastrophic events and their interactions with density-dependence patterns, the projected extinction risk increased dramatically, especially for small populations. Given that many European Dalmatian pelican populations are small, most of them could be at risk for local extinction. Our results illustrate the critical and general importance of considering interactions between all potential factors of extinction in population viability assessments.
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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 | 0.002 |
| 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".