Space-use strategies of wintering Ovenbirds in Belize: causes and consequences
Bibliographic record
Abstract
For long-distance migrants, territoriality and prey biomass during the non-breeding season have been linked to body condition that can carry over to affect spring migration and breeding events. For Ovenbirds (Seiurus aurocapilla), studies in Jamaica showed that body condition in mid-season depended on leaf litter prey biomass and declined seasonally as conditions became drier, and that individuals with sedentary (territorial) and wandering space-use strategies did not differ in age or body condition. During October and November 2010–2011, we radio-tracked Ovenbirds in Belize to determine if space-use patterns differed with age and sex, if space-use strategy influenced foraging behavior or body condition, and if areas used by wanderers and territory owners differed in food abundance or habitat characteristics. Most Ovenbirds (41 of 51, 80.4%) possessed small (1-ha) territories with largely non-overlapping cores, but 22.5% (10 of 51) of birds were wanderers (∼7-ha home range). Early season space use was predicted by age class, with most wanderers (90%, 9 of 10) being first-year birds and most territory owners (63%) being older birds. Sex ratios of wanderers and territory owners did not differ. We found that wanderers may have been at a disadvantage because they had significantly lower foraging rates and lower relative body masses than territorial birds, although baseline corticosterone levels did not differ. Habitat characteristics of areas used by wanderers and territory owners did not differ nor did biomass of ground-surface arthropods, likely because ranges of most wanderers overlapped those of territory owners. Using stable hydrogen isotopes in feathers, we found that first-year Ovenbirds that were wanderers tended to have a more northern natal origins than sedentary birds, though the difference was not significant. Longer migration distances could delay arrival and reduce competitive ability. Our results suggest that wandering may not be an alternative and equally successful strategy, at least early in the season, and instead young birds may be competitively excluded from territory ownership. Estrategias en el uso del espacio de aves horneras durante el invierno en Belice: causas y consecuencias Para migrantes de larga distancia, la territorialidad y la biomasa de las presas durante la temporada no reproductiva han sido ligados a la condición corporal, las cuales pueden tener efectos sobre la migración de primavera y los eventos de reproducción. En Seiurus auricapilla, estudios en Jamaica han demostrado que la condición corporal en la mitad de la temporada, depende de la biomasa de las presas en la hojarasca y disminuye estacionalmente a medida que las condiciones se tornan mas secas. Además, los individuos con estrategias sedentarias (territoriales) y nómadas, mostraron tener valores similares de edad y condición corporal. Durante los meses de Octubre y Noviembre de 2010–2011, seguimos los movimientos de Seiurus auricapilla en Belice, utilizando radio transmisores, con el fin de determinar si: los patrones del uso del espacio diferían entre individuos de diferentes edades y sexos, si la estrategia del uso del espacio influenciaba el comportamiento de forrajeo o la condición corporal y si la áreas usadas por individuos nómadas y territoriales mostraban diferencias en la abundancia del alimento y las características del hábitat. La mayoría de individuos de Seiurus auricapilla estudiados (41 de 51, 80.4%), mantienen territorios pequeños (1 ha) que no se sobreponen entre si, pero el 22.5% (10 de 51) de las aves son nómadas (rango de hogar ∼ 7 ha). El uso del espacio en el inicio de la temporada fue predicha por la edad, siendo la mayoría de las aves nómadas (90%, 9 de 10), individuos de primer año, y la mayoría de los individuos que mantenían territorios fueron individuos mas mayores al primer año (63%). La proporción de los sexos entre individuos sedentarios y nómadas no fue diferente. Encontramos que los individuos nómadas, pueden estar en desventaja porque tienen tasas de forrajeo significativamente menores y menor masa corporal que los individuos territoriales, a pesar de no mostrar diferencias en la línea base de los niveles de corticoesterona. Las características del hábitat y de la biomasa de artrópodos en la superficie del suelo no difirió entre los territorios de los individuos territoriales y los individuos nómadas, probablemente porque los rangos de hogar de los individuos nómadas se sobrepuso en gran medida con el territorio de individuos territoriales. Utilizando isotopos estables de hidrógeno en las plumas, encontramos que los individuos de primer año que eran nómadas, tienden a originarse mas al norte que individuos sedentarios, sin embargo la diferencia no fue significativa. Distancias mas largas de migración pueden demorar la llegada de los individuos y reducir su habilidad para competir. Nuestros resultados sugieren que el nomadismo puede no ser una alternativa y estrategia igualmente exitosa, por lo menos en el inicio de la temporada, en cambio, los individuos juveniles pueden ser excluidos de los territorios mediante competencia.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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 source (direct Gemma or distilled Codex), 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".