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Anthropogenic changes to landscapes associated with intensive agriculture often have deleterious effects on avian abundance. However, some species like the Lesser Snow Goose (Anser caerulescens caerulescens), can benefit from increases in agricultural crops on both wintering and migratory stopover sites. We investigated the influence of winter habitat use on spring body condition in Lesser Snow Goose, a species that has increased in population following expansion into agriculturally based winter habitats. We used stable isotope measurements of four elements (δ2H, δ13C, δ15N, and δ34S) to determine likely prior winter habitat use of snow geese collected during spring migration across Arkansas, Missouri, and Nebraska in 2016. We evaluated differences in body size, lipid, and protein reserves from individuals with isotope values that suggested winter habitat use in traditional coastal marsh and non-coastal /agriculture habitat. Inferred winter habitat influenced total body lipid levels in snow geese collected during spring migration. Adult and juvenile individuals inferred to have overwintered in coastal marsh (n = 60) had, on average, 33.4 g (95% Confidence Interval: 0.4 g, 66.4 g) less lipid than counterparts wintering in non-coastal / agricultural habitat (n = 77). Waterfowl foods found in marshes typically have low true metabolizable energy values as a consequence of their high fiber content, which likely increases daily consumption rates. Increased energy expenditure related to greater time spent foraging, paired with lower energetic rewards, may result in lower lipid reserves among geese using coastal marsh habitats compared to birds using agricultural landscapes. Consequently, carry-over effects based on winter habitat use could explain variation in lipid reserves among individuals during spring migration and may ultimately explain differential fitness rates or susceptibility to harvest. Our results have implications for the conservation and management of this species as historic wetland landscapes become more intensively converted and used for agricultural purposes.

Declining numbers of Blackpoll Warblers (Setophaga striata) have been documented at long-term migration monitoring sites as well as in breeding areas. However, the “loop migration” of Blackpoll Warblers makes it difficult to ascribe population change at migration monitoring sites to specific breeding populations. Individuals from all populations across the breeding range of Blackpoll Warblers concentrate in fall along the Atlantic coastline of eastern North America prior to initiating a transoceanic flight to wintering areas. In spring, Blackpoll Warblers return along a different route, moving north into the southeastern United States where birds from eastern and western breeding populations then diverge during migration to reach their respective breeding areas. To monitor breeding populations outside of breeding areas and identify factors potentially affecting those populations, we must be able to identify where birds captured during migration breed and map seasonal variation in population-specific flyways. To “map” population-specific migration movements of Blackpoll Warblers, we used feather deuterium (δ2Hf) values and a spatially explicit model to assign molt origins of 289 Blackpoll Warblers moving through sites in the Gulf of Maine (GOM) region and at three locations further west and south (northern Great Lakes area, Pennsylvania, and Florida). The assignment method was validated with feather samples from 35 birds captured during the breeding season at Churchill, Manitoba, Canada. As predicted, the spatial pattern of movement within and between seasons reflected “loop migration.” Blackpoll Warblers captured during fall migration in the GOM region included birds from across their breeding range, whereas birds captured during the spring were exclusively from northeastern populations. During fall migration, Blackpoll Warblers captured at two sites west of the GOM were from breeding areas further northwest than those from western Canada that were captured in the GOM. Blackpoll Warblers captured in eastern Florida during spring migration were assigned exclusively to breeding areas in the northeast, suggesting that eastern and western populations diverge soon after entering the United States. Finally, most Blackpoll Warblers sampled at Manomet Bird Observatory originated from breeding populations in Alaska and western Canada that have shown a similar (70–90%) decline over the same period. Our results, therefore, not only document the “loop migration” pattern of Blackpoll Warblers, but, by mapping patterns of connectivity between breeding and non-breeding areas, may help target conservation efforts for breeding populations of Blackpoll Warblers where most needed. RESUMEN Evidencia isotopico (δ2Hf) de un “circuito de migracion” y el uso de una ruta migratoria por el Golfo de Maine por ambas poblaciones reproductoras occidentales y orientales de Setophaga striata En los sitios de monitoreo de la migracion a largo plazo, y tambien en las areas de reproduccion, se han documentado la disminucion del numero de Setophaga striata. Sin embargo, el “circuito de migracion” de S. striata hace dificil atribuir los cambios de demograficos a poblaciones reproductoras especificas en los sitios de monitoreo de migracion. Antes de iniciar un vuelo transoceanico a las areas de invernada, individuos de S. Striata, de todas las poblaciones de todo el area de reproduccion, se concentran en el otono a lo largo de la costa atlantica del este de America del Norte. En primavera, S. striata regresan por una ruta diferente, moviendose al norte, entre el sureste de los Estados Unidos donde las poblaciones reproductoras del este y oeste se divergen durante la migracion para llegar a sus respectivas areas de reproduccion. Para monitorear poblaciones reproductoras fuera de las areas de reproduccion e identificar los factores que puedan afectar a esas poblaciones, debemos ser capaces de identificar donde las aves, que fueron capturadas durante la migracion, se reproducen y a mapear la variacion estacional en las rutas migratorias especificas a cada poblacion. Para mapear los movimientos migratorios de cada poblacion de S. striata, utilizamos los valores de deuterio (δ2Hf) en las plumas y un modelo espacialmente explicito para asignar origenes de muda de S. striata en movimiento a traves de sitios en la region del Golfo de Maine (GOM) y en tres lugares mas al oeste y al sur (norte de la zona de los Grandes Lagos, Pensilvania y Florida). El metodo de asignacion fue validado con muestras de plumas de 35 aves que fueron capturadas durante la temporada de cria en Churchill, Manitoba, Canada. Como se predijo, el patron espacial de movimiento dentro y entre temporadas refleja el “circuito de migracion.” Individuo S. striata capturadas durante la migracion de otono en la region del Golfo de Maine incluyo las aves de toda su area de reproduccion, en cambio, las aves capturadas durante la primavera eran exclusivamente de las poblaciones del noreste. Durante la migracion de otono, S. striata capturadas en dos sitios al oeste del Golfo de Maine eran de zonas de cria mas al noroeste que las aves de Canada occidental, lo cual fueron capturados en el Golfo de Maine. S. striata capturadas en el este de la Florida durante la migracion de primavera fueron asignados exclusivamente a las zonas de reproduccion en el noreste, lo que sugiere que las poblaciones orientales y occidentales se divergen apenas despues de entrar a los Estados Unidos. Por ultimo, la mayoria de las S. striata muestreados en el Observatorio de Aves Manomet originaron de las poblaciones de cria en Alaska y el oeste de Canada que han mostrado una disminucion de poblacion (70–90%) similar en el mismo periodo. Nuestros resultados, por lo tanto, no solo documentan el patron de un "circuito de migracion” de S. striata, pero, por los patrones de asignacion de conectividad entre areas de reproduccion y no reproductores, puede ayudar a orientar los esfuerzos de conservacion a las poblaciones reproductoras de S. striata donde mas se necesitan.

Canada Warblers (Cardellina canadensis) are long-distance Neotropical migrants, but little is known about their migratory behavior and ecology. We examined the fall migration of Canada Warblers at two sites, Darien and the Sierra Nevada de Santa Marta, in northern Colombia from 2011 to 2015 using constant-effort mist-netting. Our objectives were to determine: 1) breeding origins and connectivity patterns, 2) migratory pathways, 3) the phenology of migration, 4) possible differences in movements between ages and sexes, 5) their body condition when arriving in Colombia, and 6) evidence of stopover and refueling. Stable hydrogen isotopes (δ2Hf) in flight feathers were analyzed to estimate breeding origins of captured Canada Warblers in North America. The δ2Hf values revealed that most Canada Warblers captured in the Darien likely originated from the central and northeastern regions of their breeding range. The capture of all but one of 162 Canada Warblers in the Darien also indicates a migration route through Central American rather than across the Caribbean Sea. Most captured birds were hatch-year birds (91% vs. 9% after hatch-year birds), and we captured more females (67%) than males (33%). Canada Warblers migrated through the Darien from 20 September to early November, with most arriving in mid-October. Most (89%) individuals arrived with low fuel reserves. These results combined with estimated flight ranges revealed that 46% of the individuals captured in the Darien likely needed to refuel to continue migrating, whereas 31% could continue 50 to 200 km beyond our capture site. However, no individuals were recaptured so stopover duration could not be determined. Canada Warblers may adopt a strategy of 1-d stopovers and short flights or, alternatively, the Darien may represent low-quality habitat and birds quickly left our study site in search of suitable habitat. Further study is needed to determine the possible importance of other (montane) habitats for Canada Warblers in the Darien region to prioritize conservation actions.

Determining origins of waterfowl is important for establishing appropriate management and conservation strategies. In North America, much information is available from long-term mark-recapture programs involving banding on breeding or molting grounds. However, this approach is less able to identify origins of individuals across broad areas where banding effort is low. We used stable-hydrogen isotope analyses of feathers (δ2Hf) from Mallards (Anas platyrhynchos) harvested during the 2014-2015 and 2015-2016 hunting seasons at Lake St. Clair (LSC), Ontario, Canada (n = 237 individuals). We created a feather isoscape and applied Bayesian assignment approaches to determine probability of origin. The proportion of hatch-year Mallards produced locally, i.e., at the same latitude as LSC, as opposed to farther north or south of LSC, ranged from 13.1% to 22.0% with almost no difference by sex. The proportion of after-hatch-year (AHY) birds that molted locally ranged from 3.5% to 11.7%, with slightly fewer local AHY females compared with local AHY males. Nearly all birds that did not originate locally came from latitudes to the north of LSC, and only 2 from south of LSC. Whether this pattern is representative of locations in the Great Lakes beyond our study area is unknown but is of great relevance for harvest management. As such, we are expanding our study with plans to examine isotope-based origins of Mallards and other harvested waterfowl species at locations throughout the Great Lakes region. Because of its unique potential to fill knowledge gaps, we advocate the use of the stable isotope technique in the management of North American waterfowl and encourage more research in this area.

White sand terra firme forests are unusual ecosystems scattered across Amazonia, covering just 3% of the basin. These forests differ from surrounding forests in their scleromorphic vegetation, low nutrient content, and propensity to harbor endemics. We report the capture of 62 Gray-cheeked Thrushes (Catharus minimus) during a study of the understory avifauna of Amazonian white sand forests near Iquitos, Peru, conducted from 20 June to 8 December 2010–2012. We captured and banded Gray-cheeked Thrushes in white sand (N = 57) and adjacent weathered clay (N = 5) terra firme forests. Sampling for three consecutive days at 19 different sites each year, the inter-annual site fidelity rate of Gray-cheeked Thrushes was 4.8% (N = 3). One bird banded in 2010 was recaptured in 2012. Of the 62 birds, 19.3% (N = 12) were recaptured on subsequent days. All recaptures were in white sand forests. The 19.3% recapture rate of Gray-cheeked Thrushes from sites re-sampled no more than 2 d in a given year suggests the presence of settled and perhaps territorial birds. Using rectrices from 12 Gray-cheeked Thrushes, stable-hydrogen isotope analyses (δ2H) suggest that the geographic breeding or natal origin of all sampled birds was likely northwestern North America. Our results suggest that Gray-cheeked Thrushes exhibit site fidelity and may concentrate in white sand forests—an uncommon and scattered ecosystem type in western Amazonia. However, annual tracking of individual Gray-cheeked Thrushes is needed to fully assess regional patterns of settlement and movement, and the connectivity between breeding and wintering areas.

There is an overdue and urgent need to establish patterns of migratory connectivity linking breeding grounds, stopover sites, and wintering grounds of migratory birds. Such information allows more effective application of conservation efforts by applying focused actions along movement trajectories at the population level. Stable isotope methods, especially those using stable hydrogen isotope abundance in feathers ( 2 Hf) combined with Bayesian assignment techniques incorporating prior information such as relative abundance of breeding birds, now provide a fast and reliable means of establishing migratory connectivity, especially for Neotropical migrants that breed in North America and molt prior to fall migration. Here we demonstrate how opportunistic sampling of feathers of 30 species of wintering birds in Cuba, Venezuela, Guatemala, Puerto Rico, and Mexico, regions that have typically been poorly sampled for estimating migratory connectivity, can be assigned to breeding areas in North America through both advanced spatial assignment to probability surfaces and through simpler map lookup approaches. Incorporating relative abundance information from the North American Breeding Bird Survey in our Bayesian assignment models generally resulted in a reduction in potential assignment areas on breeding grounds. However, additional tools to constrain longitude such as DNA markers or other isotopes would be desirable for establishing breeding or molt origins of species with broad longitudinal distributions. The isotope approach could act as a rapid means of establishing basic patterns of migratory connectivity across numerous species and populations. We propose a large-scale coordinated sampling effort on the wintering grounds to establish an isotopic atlas of migratory connectivity for North American Neotropical migrants and suggest that isotopic variance be considered as a valuable metric to quantify migratory connectivity. This initiative could then act as a strategic template to guide further efforts involving stable isotopes, light-sensitive geolocators, and other technologies.

Every year brings with it a host of issues and developments that impinge directly or indirectly on the conservation of birds from local to global scales and 2015 was no exception. Most readers will be familiar with the usual list of concerns that collectively describe the threats to birds and other wildlife caused by the emergence of the Anthropocene, or the era that now typifies the impact of humans on all aspects of life on earth. Within this milieu, we find ourselves challenged to conserve the world’s avifauna with an urgency that is unprecedented. In Canada our challenges are compounded, in part, by a perception among many that most factors affecting populations of birds must be happening elsewhere and that we still occupy a land of endless wilderness punctuated by a relatively small human population. The facts of course speak otherwise. At Avian Conservation and Ecology, we see our role primarily as one of providing the best scientifically defensible evidence possible that bears on the conservation of birds in Canada and throughout the world by publishing high-quality, peer-reviewed scientific papers. However, we also try to promote an open dialogue among our readers on current issues and concerns and part of this will be through the publication of guest editorials. The first of these was by Dr. Linda Wires who bravely challenged the practice of massive population reduction practices directed at Double-crested Cormorants (Phalacrocorax auritus) underway in the United States (Wires 2015). We plan to continue this tradition and readers are encouraged to contact the editors with suggestions. Within the realm of avian conservation, two events in 2015 will also be of interest to our readers. The first was the release of a film that featured a number of studies underway largely in Canada and the USA that pertain directly to the conservation of songbirds, and the other was a paper reminding us of the generally inadequate protection of most of the world’s migratory birds. Together, these very different developments serve to underline a new urgency in avian conservation in general, and the need for a paradigm shift in the way we deal with landbird conservation in the Americas in particular.

Data from the North American Breeding Bird Survey (BBS) suggest that populations of aerial insectivorous birds are declining, particularly in northeastern regions of the continent, and particularly since the mid-1980s. Species that use nest boxes, such as Tree Swallows (Tachycineta bicolor), may provide researchers with large data sets that better reveal finer-scale geographical patterns in population trends. We analyzed trends in occupancy rates for ca. 40,000 Tree Swallow nest-box-years from 16 sites across North America. The earliest site has been studied intensively since 1969 and the latest site since 2004. Nest box occupancy rates declined significantly at five of six (83%) sites east of -78° W longitude, whereas occupancy rates increased significantly at four of ten sites (40%) west of -78° W longitude. Decreasing box occupancy trends from the northeast were broadly consistent with aspects of a previous analysis of BBS data for Tree Swallows, but our finding of instances of increases in other parts of the continent are novel. Several questions remain, particularly with respect to causes of these broadscale geographic changes in population densities of Tree Swallows. The broad geographic patterns are consistent with a hypothesis of widespread changes in climate on wintering, migratory, or breeding areas that in turn may differentially affect populations of aerial insects, but other explanations are possible. It is also unclear whether these changes in occupancy rates reflect an increase or decrease in overall populations of Tree Swallows. Regardless, important conservation steps will be to unravel causes of changing populations of aerial insectivores in North America. RESUME. Les donnees provenant du Releve des oiseaux nicheurs (BBS) de l’Amerique du Nord semblent indiquer que les populations d’insectivores aeriens sont en declin, particulierement dans les regions du nord-est du continent et depuis le milieu des annees 1980. Grâce aux especes qui utilisent les nichoirs, comme l’Hirondelle bicolore (Tachycineta bicolor), les chercheurs ont acces a une grande quantite de donnees qui revelent davantage les tendances des populations a l’echelle fine. Nous avons analyse la tendance du taux d’occupation par l’Hirondelle bicolore a partir de 40 000 nichoirs-annees provenant de 16 sites repartis en Amerique du Nord. Le site le plus ancien est suivi intensivement depuis 1969 et le plus recent, depuis 2004. Le taux d’occupation des nichoirs a diminue significativement dans 5 des 6 sites (83 %) situes a l’est du 78° de longitude ouest, tandis qu’il a augmente significativement dans 4 des 10 sites (40 %) a l’ouest du 78° de longitude ouest. La tendance a la baisse de l’occupation observee dans le nord-est concorde dans les grandes lignes avec les resultats d’une analyse anterieure des donnees du BBS pour cette espece, mais les hausses que nous avons observees dans d’autres regions de l’Amerique du Nord s’averent nouvelles. Plusieurs interrogations demeurent, notamment en ce qui a trait aux causes de ces changements dans la densite des populations d’Hirondelles bicolores a grande echelle. Ces vastes tendances geographiques concordent avec l’hypothese de changements climatiques generalises qui toucheraient les aires d’hivernage, de migration ou de nidification, lesquels pourraient affecter differemment les populations d’insectes aeriens, mais d’autres explications sont aussi possibles. En outre, nous ne savons pas si ces changements du taux d’occupation refletent une hausse ou une baisse dans l’ensemble des populations d’Hirondelles bicolores. Neanmoins, pour assurer leur conservation, il sera important d’elucider les causes des changements de populations chez les insectivores aeriens en Amerique du Nord.

We are pleased to inform our readers that, as of January 2012, we have assumed the positions of Co-Editors-In-Chief of Avian Conservation and Ecology (ACE). We replace the outgoing editorial team of Drs Tom Nudds and Marc-Andre Villard who did a splendid job of launching the journal and maintaining very high standards throughout its first six years. In addition to the usual editorial tasks, those editors also set a fine tradition of including editorials for each issue, a tradition we hope to continue. The bar has indeed been set high.