DIFFERENTIAL SURVIVAL OF YEARLING AND ADULT FEMALE MALLARDS AND ITS RELATION TO BREEDING HABITAT CONDITIONS
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Bibliographic record
Abstract
Information on age-specific survivorship is vital to understanding the dynamics of avian populations, but for many avian taxa, little is known about age-related variation in survival beyond the first year of life. We used capture-recapture data from a 16-year field study of female Mallards (Anas platyrhynchos) breeding in south-central Saskatchewan to evaluate survival-rate differences between females marked in their second year (yearlings) and those marked as adults (≥2 years old). Because the breeding season is a period of high mortality for female ducks, we further sought to determine whether age differences in annual survival might vary with wetland conditions on the breeding grounds. Capture-recapture analysis based on extensions of the Cormack-Jolly-Seber model suggested that survival was best modeled to include effects of female age, with yearling females surviving at a higher annual rate (0.58 ± 0.05 SE) than adult females (0.47 ± 0.03 SE). However, additional evidence suggested that age differences in survival were most pronounced in years of low wetland abundance. Recapture rate (indicative perhaps of breeding propensity) was best modeled to include interactive effects of female age and wetland abundance, such that yearling females were recaptured at lower rates than adults in years of low wetland numbers. Collectively, our findings support the hypothesis that reduced breeding by younger females results in elevated probabilities of survival. Whether this pattern reflects reproductive constraint or trade-off decisions on the part of young birds remains to be determined. Supervivencia Diferencial en Hembras Añales y Adultas de Anas platyrhynchos y su Relación con las Condiciones del Hábitat Reproductivo Resumen. Para entender la dinámica de las poblaciones de aves es vital contar con información sobre la supervivencia específica por edad, pero para muchos taxa de aves se conoce poco sobre la variación en supervivencia en relación a la edad luego del primer año de vida. Utilizamos datos de 16 años de trabajo de campo sobre captura-recaptura de hembras de Anas platyrhynchos que se reprodujeron en el centro-sur de Saskatchewan. Con estos datos evaluamos las diferencias en la tasa de supervivencia entre hembras marcadas en su segundo año (hembras añales) y aquellas marcadas como adultos (≥2 años de edad). Debido a que la estación reproductiva es un período de alta mortalidad para las hembras, queríamos además determinar si las diferencias de edad en la supervivencia anual variaban en relación a las condiciones de las áreas reproductivas de los humedales. Los análisis de captura-recaptura basados en extensiones del modelo de Cormack-Jolly-Seber sugirieron que la supervivencia era modelada mejor al incluir los efectos de la edad de la hembra, con una tasa anual de supervivencia más alta para hembras añales (0.58 ± 0.05 EE) que para hembras adultas (0.47 ± 0.03 EE). Sin embargo, evidencia adicional sugirió que las diferencias en la supervivencia por edad fueron más pronunciadas en los años con menor número de humedales. La tasa de recaptura (tal vez indicativa de la predisposición a reproducirse) fue modelada mejor al incluir los efectos de la interacción entre edad de la hembra y abundancia de los humedales. De este modo, las hembras añales fueron recapturadas a una tasa menor que las hembras adultas en años con escaso número de humedales. Colectivamente, nuestros resultados apoyan la hipótesis de que una reducción en la reproducción por parte de las hembras más jóvenes da como resultado un aumento en su probabilidad de supervivencia. Aún queda por determinar en las aves jóvenes si este patrón refleja limitantes reproductivas o decisiones de compromiso.
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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) | 0.002 | 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 it