AGE AND SEX DISTRIBUTIONS OF WINTERING SURF SCOTERS: IMPLICATIONS FOR THE USE OF AGE RATIOS AS AN INDEX OF RECRUITMENT
Bibliographic record
Abstract
We assessed age- and sex-specific distribution patterns of Surf Scoters (Melanitta perspicillata) wintering in southern coastal British Columbia, Canada, and evaluated potential biases associated with the use of male age ratios as an index of their recruitment. For surveys conducted during 2000 through 2002, annual variations in male age ratios were evident, with estimates ranging from 0.07 ± 0.02 to 0.13 ± 0.03 (SE; first-year males:total males). Flock composition patterns indicated first-year males did not distribute independently, but tended to associate with other first-year males. With respect to habitat, male age- class proportions did not vary among shoreline substrate types, but higher proportions of first-year males were found in sites with low exposure to wind and waves (<50 km fetch). To determine the efficacy of male age ratios for indexing recruitment, we used a power analysis, which incorporated overdispersion in age-class segregation and determined the sample sizes required for precise estimates of the proportion of first-year male Surf Scoters. Samples of approximately 600–1000 total males were required to obtain 95% confidence limits within 5% of the estimated mean, with sampling accuracy leveling off at about 2% when 6000 or more males were aged. Recruitment among waterfowl species is typically modeled using the ratio of female recruits to breeding-age females. Based on the sex and male age-ratio estimates obtained in this study, we calculated a female age ratio of 0.23 (first-year females:adult females). Distribuciones Invernales de Edad y Sexo en Melanitta perspicillata: Implicancias del Uso de Cocientes de Edad como un Índice de Reclutamiento Resumen. Estimamos los patrones de distribución específicos de edad y sexo de Melanitta perspicillata invernando en la zona costera sur de la Columbia Británica, Canadá, y evaluamos los sesgos potenciales asociados con el uso de cocientes de edad de machos como un índice de su reclutamiento. Durante los muestreos realizados entre el 2000 y el 2002 las variaciones anuales en el cociente de edad de los machos fueron evidentes, con estimaciones que variaron entre 0.07 ± 0.02 (EE) y 0.13 ± 0.03 (machos del primer año: total de machos). Los patrones de composición de las bandadas indicaron que los machos del primer año no se distribuyeron independientemente, sino que tendieron a asociarse con otros machos del primer año. Con relación al hábitat, las proporciones de clases de edad de los machos no variaron entre los tipos de substrato de la línea de costa, pero se encontraron mayores proporciones de machos del primer año en sitios con baja exposición al viento y a las olas (sitios de mar abierto <50 km de ancho). Para determinar la eficacia de los cocientes de edad de los machos como índice de reclutamiento, usamos un análisis de poder, el cual incorporó sobre-dispersión en la segregación de las clases de edad y determinó los tamaños de muestreo necesarios para estimaciones precisas de la proporción de machos del primer año de M. perspicillata. Muestras totales de aproximadamente 600–1000 machos fueron necesarias para obtener límites de confianza del 95% dentro del 5% de la media estimada, con la exactitud de muestreo nivelándose cerca del 2% luego de estimarse la edad de 6000 o más machos. El reclutamiento entre las especies de Anseriformes es modelado típicamente usando el cociente entre nuevas hembras y hembras en edad reproductiva. Basados en las estimaciones de cocientes de sexo y edad de los machos obtenidas en este estudio, calculamos un cociente de edad de las hembras de 0.23 (hembras del primer año: hembras adultas).
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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 | 0.000 |
| 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".