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We recovered 12 archival geolocators deployed on Eastern Kingbirds (Tyrannus tyrannus) breeding in New York (NY; re = 3, 2 with 2 years of data), Nebraska (NE; /; = 6, 1 with 2 years of data), and Oregon (OR; n = 3) to describe migratory routes, timing and rates of migration, nonbreeding season distributions, and migratory connectedness. NY fall migrants migrated along the.Atlantic coast to Florida, flew either nonstop across the Gulf of Mexico (GoM; 2 of 3 birds) or stopped once along the way (Cuba and Cayman Islands in different years) to land in Yucatan/Central America. Fall birds from NE and OR arrived at the GoM in the region of the border between Texas and Louisiana, and most likely took a land route to Central America. In spring, all NY birds flew nonstop across the GoM. and once in North America, took a more inland route than in fall. Trans-GoM flights were more common among NE and OR birds in spring than fall. Birds migrated faster in spring than fall, and in both seasons, late departure was associated with more rapid migration. Migratory connectivity was low, and all birds from OR. and one bird from NE and NY each, occupied a single region in northwestern Amazonia (southern Colombia, northern Peru, and eastern Ecuador) while in South America. Most kingbirds from NE and NY were intratropical migrants, occupying 2 regions for periods of [greater than or equal to]30 d. The latter birds migrated farther south to western Brazil and northern Bolivia, but then moved north to later use the same area in northwestern Amazonia where other birds remained throughout the overwinter period. Northwestern Amazonia thus appears to be a critical area for all Eastern Kingbirds during the nonbreeding season, possibly because a prolonged wet season supports abundant fruit resources. Key words: archival geolocator. departure date, intratropical migration, migration rate, migratory connectivity. Recuperamos 12 geolocalizadores que habíamos puesto en mosqueros Tyrannus tyrannus que anidaban en New York (NY; n = 3. 2 con 2 años de datos). Nebraska (NE: n = 6. 1 con 2 años de datos) y Oregon (OR; n = 3) para describir sus rutas migratorias, temporalidad y tasas de migración, distribuciones durante la temporada no-reproductiva y conectividad migratoria. En otoño, los de NY migraron a lo largo de la costa del Atlántico a Florida, volaron sin parar el cruce del Golfo de México (GoM; 2 de 3 pájaros) o hicieron una parada en el camino (Cuba e Islas Caimán en años diferentes) para aterrizar en la península de Yucatán/Centroamérica. En otoño, los pájaros de NE y OR llegaron al GoM en la región limítrofe entre Texas y Louisiana, y lo más probable es que hayan tomado una ruta de tierra firme a Centroaméríca. En primavera, todos los pájaros de NY cruzaron el GoM sin parar y una vez en Norteamérica tomaron una ruta más tierra adentro que en otoño. Los vuelos trans-GoM fueron más comunes entre los pájaros de NE y OR en primavera que en otoño. Estos pájaros migraron más rápido en primavera que en otoño: en ambas temporadas, una partida tardía estuvo asociada con una migración más rápida. La conectividad migratoria fue baja y todos los pájaros de OR. uno de NE y uno de NY ocuparon una región única de la Amazonia noroccidental (sur de Colombia, norte de Perú y el este de Ecuador) mientras permanecieron en Sudamérica. La mayoría de los mosqueros de NE y NY fueron migratorias intratropicales que ocuparon 2 regiones por periodos de [mayor que o igual a]30 d. Éstos últimos migraron más al sur al occidente de Brasil y al norte de Bolivia, pero después se movieron al norte para utilizar la misma área en la Amazonia noroccidental donde el resto de los individuos permanecieron a lo largo del periodo no-reproductivo. La Amazonia noroccidental parece ser un área crítica para todos los T. tyrannus durante la temporada no-reproductiva, posiblemente porque su prolongada estación húmeda da soporte a abundantes frutos. Palabras clave: conectividad migratoria, fecha de partida, geolocalizadores. migración intratropical, tasa de migración., Events outside the breeding season account for up to three-quarters of the annual cycle of Nearctic--Neotropical songbirds, yet basic information on wintering site locations, migratory pathways, connectivity of populations, and [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2008.10.025 Byline: Lucas J. Redmond, Michael T. Murphy, Amy C. Dolan, Karen Sexton Abstract: The study of breeding habitat selection has focused mainly on physical characteristics of the environment such as nest sites and food abundance, both of which are required for successful reproduction. However, individuals may have limited time to make settlement decisions, and thus, their knowledge of resource availability may be incomplete. Furthermore, food abundance during settlement may not reflect levels later in the breeding season. An alternative perspective is that the most direct measure of habitat suitability is derived from social information such as the presence of conspecifics (conspecific attraction) or their reproductive performance (habitat copying). We tested resource and socially based hypotheses of habitat selection in a population of eastern kingbirds, Tyrannus tyrannus, at Malheur National Wildlife Refuge in southeastern Oregon, U.S.A. Kingbirds nested in areas with a greater proportion of suitable nest trees than what was generally available, but many areas with suitable numbers of trees went unused. Kingbirds also settled in areas of relatively high insect abundance, but only in years when overall abundance was low. We also found support for the socially based hypotheses. Relative to where they nested previously, kingbirds tended to settle in areas of higher conspecific density. But, we found stronger evidence in favour of habitat copying, suggesting that dispersing individuals settled in areas that produced more fledglings in the previous year. Kingbirds thus appeared to select breeding habitat based, in part, on resource availability, but dispersal decisions may be influenced by social information, primarily past reproductive success of conspecifics. Author Affiliation: Department of Biology, Portland State University, U.S.A. Article History: Received 9 March 2008; Revised 27 June 2008; Accepted 10 October 2008 Article Note: (miscellaneous) MS. number: A08-00154R

The reuse of old nests by open-cup nesting passerines is a seemingly rare but potentially adaptive behavior if, as a consequence, females begin to breed earlier, lay larger clutches, or fledge more young. We report an unusually high rate of nest reuse (~10% of 341 nests) for Eastern Kingbirds (Tyrannus tyrannus) breeding at Malheur National Wildlife Refuge, Oregon. We found no difference in availability of nesting habitat or food abundance in territories in which nests were and were not reused. We also found no support for the hypotheses that kingbirds benefited from nest reuse by breeding earlier, laying larger clutches, or fledging more young, and, contrary to expectations, females that reused nests laid significantly smaller eggs than females who built their own nests. Nest reuse was independent of age: a roughly equal number of females for which we had multiple years of data both reused nests and built new nests, but at different points in their lives. Competition for nest sites seems high at Malheur National Wildlife Refuge because many open-cup nesting species utilize similar nest sites in the limited zone of riparian vegetation. A shortage of high-quality nest sites, coupled with interspecific competition, may underlie the high frequency of nest reuse in this kingbird population. Key words: clutch size, egg mass, interspecific competition, nest reuse, timing of breeding, Tyrannus tyrannus. La reutilizacion de nidos antiguos por aves paserinas que construyen nidos en forma de taza abierta es un comportamiento inusual que podria ser adaptativo si a consecuencia de este, las hembras empiezan a reproducirse mas temprano, ponen mas huevos o crian un mayor numero de polluelos. Presentamos datos sobre una tasa inusualmente alta de uso de nidos previamente usados (aproximadamente un 10% de 341 nidos) por parte de individuos de la especie Tyrannus tyrannus que se encontraban criando en el Refugio Nacional de Vida Silvestre Malheur. No encontramos ninguna diferencia en la disponibilidad de habitat de nidificacion ni en la abundancia de alimentos entre territorios en los cuales los nidos fueron usados nuevamente y territorios en los que los nidos solo fueron usados una vez. Ademas, no podemos sostener la hipotesis de que estas aves se benefician de volver a usar nidos pudiendo reproducirse mas temprano, poner mayor numero de huevos o criar mayor numero de polluelos. Ademas, contrariamente a lo esperado, las hembras que volvieron a usar nidos antiguos pusieron huevos significativamente mas pequenos que aquellas que construyeron nidos nuevos. El uso de nidos previamente usados fue independiente de la edad: un numero aproximadamente igual de hembras para las cuales teniamos datos de varios anos usaron nidos de nuevo o construyeron nidos nuevos, pero en diferentes momentos de su vida. Aparentemente, la competencia por sitios de nidificacion en el Refugio Nacional de Vida silvestre Malheur es alta, dado que varias especies que emplean nidos en forma de taza abierta usan sitios de nidificacion similares en una zona limitada de habitat ribereno. La escasez de sitios de nidificacion de alta calidad, junto con un alto nivel de competencia interespecifica, pueden explicar la alta tasa de reutilizacion de nidos en esta poblacion de T. tyrannus.