Full lifetime perspectives on the costs and benefits of lay date variation in tree swallows

Animals must balance various costs and benefits when deciding when to breed. The costs and benefits of breeding at different times have received much attention, but most studies have been limited to investigating short-term season-to-season fitness effects. However, breeding early, versus late, in a season may influence lifetime fitness over many years, trading off in complex ways across the breeder?s lifepan. In this study, we examined the complete life histories of 867 female tree swallows (Tachycineta bicolor) breeding in Ithaca, New York, between 2002 and 2016. Earlier breeders outperformed later breeders in short-term measures of reproductive output and offspring quality. Though there were weak indications that females paid long-term future survival costs for breeding early, lifetime fledgling output was markedly higher overall in early-breeding birds. Importantly, older females breeding later in the season did not experience compensating life-history advantages that suggested an alternative equal-fitness breeding strategy. Rather, most or all of the swallows appear to be breeding as early as they can, and differences in lay dates appear to be determined primarily by differences in individual quality or condition. Lay date had a significant repeatability across breeding attempts by the same female, and the first lay date of females fledged in our population was strongly influenced by the first lay date of their mothers, indicating the potential for ongoing selection on lay date. By examining performance over the entire lifespan of a large number of individuals, we were able to clarify the relationship between timing of breeding and fitness and gain new insight into the sources of variability in this important life history trait.Fil: Winkler, David Ward. Cornell University; Estados UnidosFil: Hallinger, Kelly K.. Cornell University; Estados UnidosFil: Pegan, Teresa M.. University of Michigan; Estados UnidosFil: Taff, Conor C.. Cornell University; Estados UnidosFil: Verhoeven, Mo A.. University of Groningen; Países BajosFil: Van Oordt, David Chang. Cornell University; Estados UnidosFil: Stager, Maria. University of Montana; Estados UnidosFil: Uehling, Jennifer J.. Cornell University; Estados UnidosFil: Vitousek, Maren N.. Cornell University; Estados UnidosFil: Andersen, Michael J.. University of New Mexico; Estados UnidosFil: Ardia, Daniel R.. Franklin & Marshall College; Estados UnidosFil: Belmaker, Amos. Tel Aviv University; IsraelFil: Ferretti, Valentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Forsman, Anna M.. University Of Central Florida; Estados UnidosFil: Gaul, Jennifer R.. International High School at La Guardia Community College; Estados UnidosFil: Llambias, Paulo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Orzechowski, Sophia C.. Harvard University; Estados UnidosFil: Shipley, Ryan. Max Planck Institute For Animal Behavior; AlemaniaFil: Wilson, Maya. Virginia Polytechnic Institute. Department Of Geological Sciences; Estados UnidosFil: Yoon, Hyun Seok. University of Tennessee; Estados Unido

Negligible effects of blood sampling on reproductive performance and return rates of Tree Swallows

Blood sampling is a frequently used method of collecting genetic and physiological data in natural populations, and understanding the possible impact of blood sampling on individuals and populations is important, both for the welfare of study organisms and to avoid introducing bias into analyses using bled individuals. Most studies of birds have revealed minimal negative effects of blood sampling. However, Brown and Brown (2009. Auk 126: 853–861) found that blood sampling reduced return rates of Cliff Swallows (Petrochelidon pyrrhonota), suggesting that these results are not always generalizable and that swallows (Hirundinidae) may be particularly sensitive to blood sampling. We examined the possible effects of blood sampling on the reproductive performance of female Tree Swallows (Tachycineta bicolor) and the return rates of both females and offspring in a population in New York state. To reduce the chances of Type II error, we tested 15 possible effects of blood sampling on reproductive performance and return rates using generalized linear mixed models. Overall, our results suggest that blood sampling had few negative effects on within‐year reproductive success or survival of adult females. The one exception was that bleeding nestlings had a negative effect on the number of young that fledged in broods of five or six nestlings. Bleeding did not negatively impact return rates of females or nestlings in our Tree Swallow population. Our results support those of other studies suggesting that blood sampling has few negative effects on within‐year reproductive success or survival of adult females, and reiterate the importance of systematically testing for possible effects with datasets compiled over multiple years because such effects may be impossible to detect via direct monitoring during a single breeding season.ResumenEfectos despreciables de la toma de muestras de sangre en el desempeño reproductivo y las tasas de retorno de Tachycineta bicolorLa toma de muestras de sangre es un método frecuentemente usado para colectar datos genéticos y fisiológicos en poblaciones naturales y es importante entender el posible impacto de la toma de muestras de sangre sobre los individuos y las poblaciones, por ambas razones, el bienestar de los organismos de estudio y para evitar la introducción de sesgos a los análisis usando individuos sangrados. Muchos estudios en aves han revelado que los efectos negativos de la toma de muestras de sangre son mínimos. Sin embargo, Brown y Brown (2009. Auk 126: 853–861) encontraron que la toma de muestras de sangre reducía la tasa de retorno en Petrochelidon pyrrhonota, sugiriendo que estos resultados no son siembre generalizables y que las golondrinas (Hirundinidae) pueden ser particularmente sensibles a la toma de muestras de sangre. Examinamos los posibles efectos de la toma de muestras de sangre en el desempeño reproductivo de Tachycineta bicolor y las tasas de retorno en hembras y crías en una población en el estado de Nueva York. Para reducir los chances de error Tipo II, probamos 15 efectos posibles de la toma de muestras de sangre en el desempeño reproductivo y las tasas de retorno usando modelos lineales mixtos generalizados. En general, nuestros resultados sugieren que la toma de muestras de sangre tuvo pocos efectos negativos sobre el éxito reproductivo intra‐anual o las tasas de supervivencia de las hembras adultas. La única excepción fue que el sangrado de los pichones tuvo un efecto negativo en el numero de juveniles que salían del nido en las nidadas de cinco o seis pichones. El sangrado no tuvo ningún impacto negativo sobre las tasas de retorno de las hembras o de los pichones en nuestra población de Tachycineta bicolor. Nuestros resultados soportan esos otros estudios que sugieren que la toma de muestras de sangre tiene pocos efectos negativos sobre el éxito reproductivo intra‐anual o sobre la supervivencia de hembras adultas y reiteran la importancia de comprobar sistemáticamente los posibles efectos en las bases de datos recopiladas a través de múltiples años por que dichos efectos pueden ser imposibles de detectar por medio de monitoreos durante una única temporada de reproducción.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148221/1/jofo12276_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148221/2/jofo12276.pd