SummaryNearly 300 species of landbirds, whose populations total billions, migrate between the Neotropics and North America. Many migratory populations are in steep decline, and migration is often identified as the greatest source of annual mortality. Identifying birds' needs on migration is therefore central to designing conservation actions for Nearctic-Neotropical migratory birds; yet migration through the Neotropics is a significant knowledge gap in our understanding of the full annual cycle. Here, we synthesise current knowledge of Neotropical stopover regions and migratory bottlenecks, focusing on long-distance, migratory landbirds that spend the boreal winter in South America. We make the important distinction between "true" stopover-involving multiday refuelling stops-and rest-roost stops lasting < 24 hours, citing a growing number of studies that show individual landbirds making long stopovers in just a few strategic areas, to accumulate large energy reserves for long-distance flights. Based on an exhaustive literature search, we found few published stopover studies from the Neotropics, but combined with recent tracking studies, they describe prolonged stopovers for multiple species in the Orinoco grasslands (Llanos), the Sierra Nevada de Santa Marta (Colombia), and the Yucatan Peninsula. Bottlenecks for diurnal migrants are well described, with the narrowing Central American geography concentrating millions of migrating raptors at several points in SE Mexico, Costa Rica, Panama and the Darién. However, diurnally migrating aerial insectivores remain understudied, and determining stopover/ roost sites for this steeply declining group is a priority. Despite advances in our knowledge of migration in the Neotropics, we conclude that major knowledge gaps persist. To identify stopover sites and habitats and the threats they face, we propose a targeted and collaborative research agenda at an expanded network of Neotropical sites, within the context of regional conservation planning strategies.

Research666 the probability that our method missed peaks (spatial: 0.12, temporal: 0.18) or detected false peaks (spatial: 0.11, temporal: 0.37) due to data gaps and showed that our approach remains useful even for sparse and/or sporadic location data. Our study presents a generalizable approach to evaluating migratory connectivity across the full annual cycle that can be used to focus migratory bird conservation towards places and times of the annual cycle where populations are more likely to be limited.

Removal of deciduous vegetation in managed conifer forests is a major component of most silviculture programs in North America. We examined the effect of removing 90–96% of the volume of deciduous trees on breeding bird communities in young conifer plantations during four years. Trees were removed by two treatments: manual thinning (manual treatment), and manual thinning plus application of a herbicide, glyphosate (herbicide treatment). The control and two treatments were each replicated three times. During the three post‐treatment years, the herbicide‐treated sites remained depauperate of deciduous vegetation while the manually thinned sites experienced regrowth of deciduous trees. Number of species declined, total number of individuals increased, and common species dominated after herbicide treatment. Number of species, total number of individuals, and evenness increased after manual treatment. Turnover of bird species was highest in the herbicide‐treated areas and lowest in control areas. Residents, short‐distance migrants, ground gleaners, and conifer nesters increased significantly after herbicide treatment. Deciduous nesters and foliage gleaners increased in abundance (nonsignificantly) in control and manually thinned areas. Warbling Vireos (Vireo gilvus), which are deciduous specialists, declined in areas treated with herbicide and may be particularly susceptible to glyphosate application. Although treated areas exhibited similar increases in the total number of birds, nesting success of open‐cup nesting species was significantly lower in the herbicide‐treated than in manually thinned areas. We suggest that habitat variability may be a mechanism for producing nested subset structure of bird community composition. Overall, the composition of bird communities became more homogeneous after herbicide treatment, and it showed little change after manual thinning.

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Hydroelectric dam operations that lead to fluctuations in the water levels of reservoirs can influence the amount of riparian habitat available for migrating songbirds and may impact the use and quality of remaining habitat. Our objective was to determine if use of riparian habitats and mass gain by five warbler species at the Columbia River-Revelstoke Migration Monitoring Station in British Columbia, Canada, were influenced by water levels in the surrounding Arrow Lakes Reservoir. We analyzed fall migration data collected from 1998 to 2006. Capture rates of American Redstarts (Setophaga ruticilla), Common Yellowthroats (Geothlypis trichas), Orange-crowned Warblers (Vermivora celata), Wilson's Warblers (Wilsonia pusilla), and Yellow Warblers (Dendroica petechia) varied between years and weeks of the migration period, but were not affected by annual or weekly variation in water levels. Annual variation in capture rates was driven by hatch-year birds (>80% of individuals captured were juveniles) and could reflect conditions on the breeding grounds that influence productivity. We found that mass gain by the five species of warblers varied between 0.32% and 0.98% of lean body mass/hour. Mass gain did not vary between years or across weeks of the migration period and was not influenced by annual or weekly variation in reservoir water levels. Although the amount of available riparian habitat was reduced when reservoir water levels were high, we found no evidence that this loss of habitat influenced either the number of warblers or the mass gain of warblers using the riparian habitat that remained. Body mass at the time of first capture varied between years and across weeks for all five species. For American Redstarts and Orange-crowned Warblers, body mass declined as average weekly water levels increased, a pattern that could arise if water levels influenced either their settlement decisions or length of stay. RESUMEN. Los niveles del agua en un embalse no influyen en el incremento del peso diario de parulidos en un sitio de parada migratorio riparioLas operaciones de las represas hidroeléctricas que resultan en fluctuaciones en los niveles del agua de los embalses pueden influenciar la cantidad de hábitat ripario disponible para las aves migratorias y podrían tener impacto en el uso y la calidad del hábitat remanente. Nuestro objetivo fue determinar si el uso de los hábitats riparios y el incremento en el peso de cinco especies de parulidos en la estación de monitoreo migratorio del Rio Columbia-Revelstoke en British Columbia, Canada fueron influenciados por los niveles del agua en el embalse de Arrow Lakes. Analizamos datos de la migración de otoño colectados desde 1998 hasta 2006. Las tasas de captura de Setophaga ruticilla, Geothlypis trichas, Vermivora celata, Wilsonia pusilla, y Dendroica petechia variaron entre años y semanas durante el periodo migratorio pero no fueron afectados por la variación anual o semanal en el nivel del agua. La variación anual en las tasas de captura fue influenciada por aves de primer ...