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During spring, migratory birds are required to optimally balance energetic costs of migration across heterogeneous landscapes and weather conditions to survive and reproduce successfully. Therefore, an individual's migratory performance may influence reproductive outcomes. Given large‐scale changes in land use, climate, and potential carry‐over effects, understanding how individuals migrate in relation to breeding outcomes is critical to predicting how future scenarios may affect populations. We used GPS tracking devices on 56 Greater White‐fronted Geese (Anser albifrons) during four spring migrations to examine whether migration characteristics influenced breeding propensity and breeding outcome. We found a strong longitudinal difference in arrival to the breeding areas (18 days earlier), pre‐nesting duration (90.9% longer), and incubation initiation dates (9 days earlier) between western‐ and eastern‐Arctic breeding regions, with contrasting effects on breeding outcomes, but no migration characteristic strongly influenced breeding outcome. We found that breeding region influenced whether an individual likely pursued a capital or income breeding strategy. Where individuals fell along the capital‐income breeding continuum was influenced by longitude, revealing geographic effects of life‐history strategy among conspecifics. Factors that govern breeding outcomes likely occur primarily upon arrival to breeding areas or are related to individual quality and previous breeding outcome, and may not be directly tied to migratory decision‐making across broad scales. [ABSTRACT FROM AUTHOR]

It is estimated that about 80% of North American avian migrants travel along the southern coast of Texas. Quality of stopover habitat for landbirds in southern Texas is a concern, however, due to agricultural and wind energy development and increasing urbanization. Since little regional research has been conducted on stopover habitat use, we investigated habitat associations of migratory birds to identify important factors driving density along the southern Texas coast. We did this using data from landbird surveys, which took place during spring and autumn migrations from 1991 to 1993 and 2006 to 2008, within 6 land-cover types common in southern Texas. We found that oak motte had the highest density among most bird guilds. A total of 125 species of birds were detected over the course of our study and species richness was highest in oak motte and lowest in grassland. In general, land-cover types with more woody vegetation cover tended to have higher species richness and diversity than those with minimal to no woody vegetation. Although grassland ranked lowest in other metrics of bird use, it ranked highest in habitat conservation value, which accounts for species of concern. At the time of this study. Golden-winged Warbler (Vermivora chrysoplera) was the only species on Partners in Flight's Red Watch List (highly vulnerable and in need of special attention) that we observed, with recorded observations occurring in oak motte and woodland exclusively. Oak mottes are likely a prime location for species to land after flying over the Gulf of Mexico during their journey north to their breeding grounds, thus land managers that wish to provide high-quality stopover sites for migratory landbirds should preserve them. Received I January 2021. Accepted 31 May 2021. Key words: Gulf of Mexico, migratory, oak motte, songbirds, stopover. Se estima que cerca del 80% de las aves migratorias de Norte America viajan a lo largo de la costa sur de Texas. La calidad del habitat en sitios de descanso para aves terrestres en el sur de Texas es una preocupacion. en especial por Ios desarrollos agricola. de encrgia eolica y por el incremcnto en su urbanizacion. Dado que sc ha hecho poca investigation sobre cl uso de habitats de reabastecimiento. investigamos las asociaciones de habitat de aves migratorias para identificar Ios factores de importancia responsables de su densidad a lo largo de la costa sur de Texas. Lo hicimos usando datos de reconocimientos de aves. Ios cuales tuvieron lugar durante las migraciones de primavera y otono de 1991-1993 y 2006-2008 al interior de 6 tipos de cobertura del suelo que son comunes en e! sur de Texas. Encontramos que los encinares (oak mottes) tcnian la mayor densidad en la mayoria de los gremios de aves. Un total de 125 especies de aves fueron detectadas en cl curso de nuestro cstudio; la mayor riqueza de especies fue en los encinares y mas baja en los pastizales. En general, los tipos de cobertura del suelo con mas cobertura de vegetacion lchosa tendieron a tener una mayor riqueza de especies que aquellos con cobertura minima o sin vegetacion lehosa. Aunque los pastizales estaban en la ultima posicion en otras metricas de uso por aves, estas se encontraron cn la primera posicion en valor de conservacion de habitat, que considera especies con algun estatus preocupante de conservacion. En las fechas de este estudio. el chipe Vermivora chrysoptera fue la linica especie que observamos en la lista roja de Partners in Flight (altamente vulnerable y que nccesita atencion especial), con registros que obtuvimos exclusivamente en encinares y arbolados. Los encinares son sitios de primera importancia para especies que migran sobre el Golfo de Mexico y tocan tierra durante su viajc hacia el none, camino a sus areas de reproduccion, por lo que quienes manejan la tierra que deseen proveer de sitios de aha calidad para aves terrestres migratorias deben prcservarlos. Palabras clave: aves canoras, encinares, Golfo de Mexico, migratorio, sitios de reabastecimiento., Many birds in the western hemisphere breed in North America and winter in Central and South America presumably to exploit resources at their peak occurrence, requiring a bi-annual migration (Kerlinger [...]

There is often substantial variation in habitat type and quality within species ranges and management units, especially in wetland ecosystems. This variation necessitates quantifying behavioral and habitat associations to inform conservation of wetland-dependent species. This study explored drivers of American Avocet (Recurvirostra americana) energy expenditure to evaluate patterns of habitat use during the non-breeding season at Mustang Island in Texas, U.S.A. and Rockefeller Wildlife Refuge in Louisiana, U.S.A., on the coast of the Gulf of Mexico. A Bayesian linear mixed model was used to analyze GPS-acceleration data from tracking devices on 31 American Avocets, with overall dynamic body acceleration (a proxy for energy expenditure) as a response variable and tide, time of day, day of year, and landcover as hypothesized drivers. Results suggested that landcover, tide amplitude, and time of day explained substantial variation in energy expenditure, and each site showed unique patterns in these relationships. For example, the interaction of landcover and tide was heavily influential at Rockefeller, whereas Mustang Island birds showed a substantial dichotomy in energy expenditure between day and night. Using energy expenditure to understand habitat associations could be helpful to better understand variation in habitat use and behavior and customize conservation planning in dynamic ecosystems. [ABSTRACT FROM AUTHOR]

The reddish egret Egretta rufescens is North America's rarest Ardeidae and is listed as 'Near Threatened' by the IUCN, as endangered in Mexico, and as a species of conservation concern throughout much of its range in the United States. Little is known about the migratory behavior of the reddish egret. Individuals that were banded during the breeding season in Texas, USA, have been resighted away from breeding areas; however, records are limited and the extent of migration is unknown. Using GPS transmitters, we found reddish egrets breeding in southern Texas exhibited a partial migration strategy, with 39% of the marked population migrating from breeding sites. We assessed the dominance, body size, and arrival time hypotheses to better understand the drivers of partial migration. We did not find support for the body size hypothesis and found mixed support for the dominance hypothesis; both males and females migrated, and migratory status of individuals did not change across the years of study. Long‐distance migrants were also larger than resident individuals. We found some support for the arrival time hypothesis; residents began breeding earlier than long‐distance migrants and had moderately greater nest success. However, within long‐distance migrants, an earlier arrival to breeding areas did not necessarily equate to earlier nesting or greater nest success. This study is the first to examine the migratory behavior of adult reddish egrets and assesses the dominance, body size, and arrival time hypotheses as explanations for partial migration in this species. Further, the results of this study emphasize the need for international conservation efforts. [ABSTRACT FROM AUTHOR]

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