Nest traits and major flooding events influence nest survival of Emperor Geese while regional environmental variation linked to climate does not

ABSTRACT The reproductive ecology of geese that breed in the Arctic and subarctic is likely susceptible to the effects of climate change, which is projected to alter the environmental conditions of northern latitudes. Nest survival is an important component of productivity in geese; however, the effects of regional environmental conditions on nest survival are not well understood for some species, including the Emperor Goose (Anser canagicus), a species of conservation concern that is endemic to the Bering Sea region. We estimated nest survival and examined how indices of regional environmental conditions, nest traits (nest age, initiation date, and maximum number of eggs in the nest), and researcher disturbance influenced daily survival probability (DSP) of Emperor Goose nests using hierarchical models and 24 years of nest monitoring data (1994–2017) from the Yukon–Kuskokwim Delta (Y–K Delta) in western Alaska. Our results indicate that overall nest survival was generally high (µ = 0.766, 95% CRI: 0.655–0.849) and ranged from 0.327 (95% CRI: 0.176–0.482) in 2013 to 0.905 (95% CRI: 0.839–0.953) in 1995. We found that DSPs of nests were influenced by nest traits, negatively influenced by major tidal flooding events and by researcher disturbance, but were not influenced by regional indices of spring timing, temperature and precipitation during nesting, or fox and vole abundance on the Y–K Delta. However, the number of nests found each year was negatively related to our index of fox abundance, suggesting nests that failed as a result of fox predation may have never been discovered due to our limited nest-searching efforts during egg laying. Our results suggest that regional environmental variation had minimal influence on the nest survival of Emperor Geese, although major flooding events were important. Nevertheless, we suspect that within-year variation in local weather conditions and local abundance of predators and alternative prey may be important and should be considered in future studies. How to Cite Thompson, J. M., B. D. Uher-Koch, B. L. Daniels, J. A. Schmutz, and B. S. Sedinger (2023). Nest traits and major flooding events influence the nest survival of Emperor Geese while regional environmental variation linked to climate does not. Ornithological Applications 125:duad008. LAY SUMMARY Due to projected changes in environmental conditions of northern latitudes, the reproductive ecology of geese that breed in the Arctic and subarctic is likely susceptible to the effects of climate change. No previous studies have examined the effects of regional environmental conditions on the nest survival of Emperor Geese (Anser canagicus), a species of conservation concern endemic to the Bering Sea region. We estimated the nest survival of Emperor Geese on the Yukon–Kuskokwim Delta in Alaska and quantified the effects of regional environmental variation and nest traits (nest age, nest initiation date, and number of eggs in the nest) on nest survival. Our results suggest that regional indices of spring timing, temperature and precipitation during nesting, and abundance of predators (foxes) and alternative prey (voles) did not influence nest survival of Emperor Geese, although major flooding events and nest traits appeared to be important. We recommend that future research on the nesting ecology of Emperor Geese should focus on within-year variation in local weather conditions and local abundance of predators and alternative prey. RESUMEN Es probable que la ecología reproductiva de los gansos que se reproducen en el Ártico y el subártico sea susceptible a los efectos del cambio climático, que se prevé que altere las condiciones ambientales de las latitudes del norte. La supervivencia del nido es un componente importante de la productividad de los gansos; sin embargo, los efectos de las condiciones ambientales regionales sobre la supervivencia del nido no se comprenden bien para algunas especies, incluida Anser canagicus, una especie de interés para la conservación que es endémica de la región del Mar de Bering. Estimamos la supervivencia del nido y examinamos cómo los índices de las condiciones ambientales regionales, las características del nido (edad del nido, fecha de iniciación, número máximo de huevos en el nido) y el disturbio ocasionado por el investigador influyeron en la probabilidad de supervivencia diaria (PSD) de los nidos de A. canagicus usando modelos jerárquicos y 24 años de datos de monitoreo de nidos (1994–2017) del Delta Yukón–Kuskokwim en el oeste de Alaska. Nuestros resultados indican que la supervivencia total del nido fue generalmente alta (µ = 0,766, ICR 95%: 0,655–0,849) y varió de 0,327 (ICR 95%: 0,176–0,482) en 2013 a 0,905 (ICR 95%: 0,839–0,953) en 1995. Encontramos que las PSD de los nidos fueron influenciadas por las características del nido, negativamente influenciadas por grandes eventos de inundaciones de mareas y por el disturbio del investigador, pero no fueron influenciadas por los índices regionales de la duración de primavera, la temperatura y la precipitación durante la anidación, o por la abundancia de zorros y ratones de campo, en el Delta Yukón–Kuskokwim. Sin embargo, el número de nidos encontrados cada año se relacionó negativamente con nuestro índice de abundancia de zorros, lo que sugiere que los nidos que fallaron como resultado de la depredación de los zorros pueden no haber sido descubiertos debido a nuestros limitados esfuerzos de búsqueda de nidos durante la puesta de huevos. Nuestros resultados sugieren que la variación ambiental regional tuvo una influencia mínima en la supervivencia de los nidos de A. canagicus, aunque los grandes eventos de inundaciones fueron importantes. Sin embargo, sospechamos que la variación dentro del año en las condiciones climáticas locales y en la abundancia local de depredadores y presas alternativas pueden ser importantes y deberían considerarse en estudios futuros.