Differences in insectivore bird diets in coffee agroecosystems driven by obligate or generalist guild, shade management, season, and year

Neotropical shade-grown coffee systems are renowned for their potential to conserve avian biodiversity. Yet, little is known about food resources consumed by insectivorous birds in these systems, the extent of resource competition between resident and migratory birds, or how management of shade trees might influence diet selection. We identified arthropods in stomach contents from obligate and generalist insectivorous birds captured in mist-nets at five coffee farms in Chiapas, Mexico between 2001–2003. Overall stomach contents from 938 individuals revealed dietary differences resulting from changes in seasons, years, and foraging guilds. Of four species sampled across all management systems, Yellow-green Vireo (Vireo flavoviridis) prey differed depending on coffee shade management, consuming more ants in shaded monoculture than polyculture systems. Diets of obligate and generalist resident insectivores were 72% dissimilar with obligate insectivores consuming more Coleoptera and Araneae, and generalist insectivores consuming more Formicidae and other Hymenoptera. This suggests that obligate insectivores target more specialized prey whereas generalist insectivores rely on less favorable, chemically-defended prey found in clumped distributions. Our dataset provides important natural history data for many Nearctic-Neotropical migrants such as Tennessee Warbler (Leiothlypis peregrina; N = 163), Nashville Warbler (Leiothlypis ruficapilla; N = 69), and Swainson’s Thrush (Catharus ustulatus; N = 68) and tropical residents including Red-legged Honeycreepers (Cyanerpes cyaneus; N = 70) and Rufous-capped Warblers (Basileuterus rufifrons; N = 56). With declining arthropod populations worldwide, understanding the ecological interactions between obligate and generalist avian insectivores gives researchers the tools to evaluate community stability and inform conservation efforts.

Extraordinarily rapid proliferation of cultured muscle satellite cells from migratory birds

Migratory birds experience bouts of muscle growth and depletion as they prepare for, and undertake prolonged flight. Our studies of migratory bird muscle physiology in vitro led to the discovery that sanderling ( Calidris alba ) muscle satellite cells proliferate more rapidly than other normal cell lines. Here we determined the proliferation rate of muscle satellite cells isolated from five migratory species (sanderling; ruff, Calidris pugnax ; western sandpiper, Calidris mauri ; yellow-rumped warbler, Setophaga coronata ; Swainson's thrush, Catharus ustulatus ) from two families (shorebirds and songbirds) and with different migratory strategies. Ruff and sanderling satellite cells exhibited rapid proliferation, with population doubling times of 9.3 ± 1.3 and 11.4 ± 2 h, whereas the remaining species' cell doubling times were greater than or equal to 24 h. The results indicate that the rapid proliferation of satellite cells is not associated with total migration distance but may be related to flight bout duration and interact with lifespan.

Defining catchment origins of a geographical bottleneck: Implications of population mixing and phenological overlap for the conservation of Neotropical migratory birds

Migratory bottlenecks concentrate individuals and populations of Nearctic–Neotropical migrants from across vast breeding areas. The extent to which such concentrations occur has important ramifications for interpreting migratory connectivity and for the vulnerability of populations throughout the annual cycle but investigations of such phenomena are rare. We inferred breeding origins of 11 species of Nearctic–Neotropical migrants captured during fall migration in the Darién region, northwestern Colombia, using feather stable-hydrogen isotope values (δ 2Hf). Our objectives were to determine (1) the extent to which this region acts as a catchment for individuals from across a species’ breeding range, (2) if temporal patterns of arrival arise as a function of migration distance inferred from δ 2Hf, and (3) if phenological differences among species segregate populations. The Darién concentrated populations of 6 species, with individuals potentially derived from 78% to 94% of their respective North American breeding ranges. The catchment area for the remaining 5 species covered 40–72% of breeding ranges, with a bias in origin from the west (e.g., Northern Waterthrush [Parkesia noveboracensis], Swainson’s Thrush [Catharus ustulatus]), north or center (Yellow Warbler [Setophaga petechia]) of their range. Differential timing in the migration of populations occurred in 6 species, generating a degree of temporal segregation. In contrast, peak migration for all species occurred in October, resulting in high overlap among species in their use of the Darién. Overall, our results describe high mixing of populations in the Darién for several species, which, given the region’s highly restricted geographic extent, suggests that a bottleneck effect occurs; however, comparisons with other regions in Central America and northern South America are required. The combination of extensive population mixing and limited temporal segregation over a narrow geographical area suggests that long-distance migrants may be especially vulnerable to events occurring in such regions, including adverse weather conditions and anthropogenic land cover change.

Comparing fall migration of three Catharus species using a radio-telemetry network

Migration routes vary greatly among small passerine species and populations. It is now possible to determine the routes over great distances and long periods of time with emerging monitoring networks. We tracked individual Swainson’s Thrush (Catharus ustulatus), Bicknell’s Thrush (Catharus bicknelli) and Gray-cheeked Thrush (Catharus minimus) in northeastern Quebec and compared their migration routes and paces across an array of radio-telelemetry stations in North America. Swainson’s Thrush migrated further inland than the other two species. Individuals from all three species slowed their migration pace in the southeastern United States, and Swainson’s Thrush was more likely to stopover than Bicknell’s Thrush. Although individuals were tagged in a small area within or close to their breeding range, the results document the variability of migration routes between species with similar ecological characteristics and provide detailed material to be used for migration studies with broader taxonomic or ecological scope.

Posible incidencia de viruela u otro patógeno de aves en Guatemala

Durante enero y febrero de 2019 hicimos observaciones casuales y documentamos aves con lesiones macroscópicas, aparentemente por viruela o algún tipo de tumor en la cabeza. Los individuos eran de ocho especies (cinco migratorias y tres residentes), las observamos en tres localidades distintas de Guatemala. Las especies migratorias fueron Passerina ciris (Cardinalidae), Catharus ustulatus (Turdidae), Oreothlypis peregrina (Parulidae), Piranga ludoviciana (Cardinalidae) y Pheucticus ludovicianus (Cardinalidae), y las residentes, Cyanerpes cyaneus (Thraupidae), Euphonia luteicapilla (Fringilidae) y Thraupis episcopus (Thraupidae). Aunque las lesiones se ven similares a las de la viruela, ninguno de estos individuos fue capturado, por esta razón no se ha establecido un diagnóstico definitivo. Actualmente estamos trabajando en un proyecto de investigación para tomar muestras patológicas y confirmar el diagnóstico; sin embargo, consideramos que la comunidad científica debe estar alerta respecto a esta situación, pues tanto las especies migratorias como las residentes están siendo afectadas y todavía no sabemos las consecuencias que esto podría tener en la avifauna y los ecosistemas en general.

Riqueza y abundancia de las aves urbanas de nueve áreas verdes de la ciudad de Sangolquí (Ecuador): Estudio preliminar

Este estudio se realizó con el objetivo de documentar la riqueza y la abundancia de las aves silvestres en nue-ve áreas verdes de Sangolquí. Se registró la avifauna mediante puntos de conteo a partir de las 06h30 hasta las 09h30, en días sin lluvia, desde el 11 de noviembre del 2016 hasta el 18 de febrero del 2017, mediante detección visual y auditiva. Cada uno de los nueve sectores fue muestreado a través de siete puntos de conteo consecutivos. La avifauna registrada incluyó una riqueza de 29 especies con un total de 1.010 individuos re-gistrados. La Tórtola Orejuda Zenaida auriculata fue la más abundante con 292 individuos, mientras que las especies menos abundantes, con un solo registro, fueron el Zorzal de Swainson Catharus ustulatus, Carpintero dorsicarmesi Colaptes rivolii, Gallinazo Negro Coragyps atratus, Pinchaflor Pechicanelo Diglossa sittoides y el Gavilán Alicastaño Parabuteo unicinctus. La Paloma Doméstica, el Gorrión, el Mirlo Grande y Tórtola Orejuda se consideran especies sinantrópicas para Sangolquí. Finalmente, se sugiere restaurar la cobertura arbustiva de las áreas verdes para favorecer la conservación de las aves locales.

Ecology, endemism, and conservation status of birds that collide with glass windows in Monteverde, Costa Rica

Worldwide, billions of birds die annually due to window collisions. Nevertheless, few accounts document bird-window collisions in the Neotropics. In this study, we document species that collided with windows in Monteverde, Costa Rica, and describe their ecological and conservation status. We gathered information from different sources, including data from museum records and accounts by Monteverde residents who participated as “citizen scientists” between May 2014 and December 2017. We conducted carcass searches between March 2015 and February 2016. We classified window-strike species by migratory, forest dependence, trophic guild, weight, abundance, conservation, and endemism status. We registered 103 species striking windows in Monteverde, which includes 98 of 267 species known to occur in three life zones in Monteverde and five not registered in the area. Window strike casualties’ frequencies differed by species, trophic guild and migratory status. Most window victims were residents, small, insectivorous, considered common or fairly common, with declining population trends. The families with the most species represented were Parulidae (14 spp.), Trochilidae (13 spp.), Turdidae (10 spp.), and Tyrannidae (9 spp.). Most species were passerines (Order Passeriformes) (71 spp.). No hawks or vultures were found colliding with buildings. The three species most commonly killed by windows were frugivores: Swainson’s Thrush (Catharus ustulatus), Northern Emerald-Toucanet (Aulacorhynchus prasinus), and Black-faced Solitaire (Myadestes melanops). Among window-kills were five species whose status on the IUCN Red List are Near Threatened and one Vulnerable, including the Resplendent Quetzal (Pharomachrus mocinno) and the Three-wattled Bellbird (Procnias tricarunculatus). Six species are listed as in danger of extinction and four are listed as species with reduced populations by the National System of Conservation Areas for Costa Rica (SINAC). 12 endemic species are strike casualties. The premontane wet forest is the life zone where more species were found (n=64 spp.), followed by the premontane moist forest (n = 49 spp.) and the lower montane wet forest (n = 31 spp.). These findings demonstrate the urgent need for conservation measures to mitigate bird mortality due to window collisions. Promoting use of methods to protect birds from windows should be an important goal for this IBA and the rest of Costa Rica. We also recommend collecting data in order to increase understanding about bird window collisions.