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In this investigation, we used a combination of field- and laboratory-based approaches to assess if influenza A viruses (IAVs) shed by ducks could remain viable for extended periods in surface water within three wetland complexes of North America. In a field experiment, replicate filtered surface water samples inoculated with duck swabs were tested for IAVs upon collection and again after an overwintering period of approximately 6–7 months. Numerous IAVs were molecularly detected and isolated from these samples, including replicates maintained at wetland field sites in Alaska and Minnesota for 181–229 days. In a parallel laboratory experiment, we attempted to culture IAVs from filtered surface water samples inoculated with duck swabs from Minnesota each month during September 2018–April 2019 and found monthly declines in viral viability. In an experimental challenge study, we found that IAVs maintained in filtered surface water within wetlands of Alaska and Minnesota for 214 and 226 days, respectively, were infectious in a mallard model. Collectively, our results support surface waters of northern wetlands as a biologically important medium in which IAVs may be both transmitted and maintained, potentially serving as an environmental reservoir for infectious IAVs during the overwintering period of migratory birds.

Hatchery programs have been used as a conservation tool to bolster declining populations of Chinook Salmon Oncorhynchus tshawytscha along much of the North American Pacific coast. In many watersheds, hatchery stocks are released concurrently with the wild population, thus raising the potential for density‐dependent effects. Competition for prey resources during the critical period for early marine growth and survival may diminish the foraging capacity and growth potential of wild Chinook Salmon, highlighting the importance of a diverse and productive delta habitat mosaic. We used an integrated diet approach with stomach content and stable isotope analyses to evaluate contrasting patterns of habitat use and prey consumption in a fall‐run population of juvenile Chinook Salmon from the Nisqually River delta in Puget Sound, Washington. We examined size‐class and origin‐level differences throughout a gradient of delta habitat types. Wild (unmarked) and hatchery juveniles exhibited distinct habitat use patterns whereby unmarked fish were captured more frequently in tidally influenced freshwater and mesohaline emergent marsh areas, while hatchery fish were caught more often in the nearshore intertidal zone. Consequently, hatchery fish were less likely to consume the energy‐dense terrestrial insects that were more common in freshwater and brackish marshes. Stable isotope signatures from muscle and liver tissues corroborated this finding, showing that unmarked juveniles had derived 24–31% of their diets from terrestrially sourced prey, while terrestrial insects only made up 2–8% of hatchery fish diets. This may explain why unmarked fish were in better condition than hatchery fish and had stomach contents that were 15% more energy‐rich than those of hatchery fish. We did not observe strong evidence for trophic overlap in juvenile Chinook Salmon of different rearing origins, but our results suggest that hatchery juveniles could be more sensitive to diet‐mediated effects on growth and survival.

Understanding interconnectivity among wintering, stopover, and breeding areas of migratory birds is pivotal to discerning how events occurring in each might have a cross-seasonal effect on another. Such information can guide the location and timing of conservation efforts. Thus, we examined spring migration routes, chronology, and stopover use of 85 surf scoters (Melanitta perspicillata (L., 1758)) marked with satellite transmitters at four Pacific Flyway wintering sites: San Quintin Bay, Baja California; San Francisco Bay, California; Puget Sound, Washington; and Strait of Georgia, British Columbia. Eighty-three percent of marked scoters followed two main routes to the breeding area: a Southern Inland route involving staging in Puget Sound and Strait of Georgia and protracted inland migration, or a Northern Coastal route characterized by short movements along the Pacific coast of British Columbia and southeast Alaska with inland migration initiating from Lynn Canal and surrounding areas. Route choice was related to nesting site latitude in the Canadian Northern Boreal Forest. Data from birds tracked over 2 years indicated strong migration route fidelity, but altered chronology and stopover locations between years. Departure date varied by wintering site, but arrival and apparent settling dates were synchronous, suggesting individuals adjusted migration timing to meet an optimized reproductive schedule.Résumé : La compréhension de l'interconnectivité entre les zones d'hivernage, d'arrêt et de reproduction chez les oiseaux migrateurs est essentielle si l'on veut voir comment les événements qui se passent dans chacune de ces zones peuvent avoir un effet lors d'une autre saison dans une autre zone. De telles informations pourraient orienter le choix des sites et du moment des interventions de conservation. Nous avons ainsi examiné les routes printanières de migration, leur chronologie et l'utilisation des points d'arrêt chez 85 macreuses à front blanc (Melanitta perspicillata (L., 1758)) munies d'émet-teurs satellites à quatre sites d'hivernage sur la route de migration du Pacifique, la baie de San Quintin en BasseCalifornie, la baie de San Francisco en Californie, Puget Sound au Washington et le détroit de Géorgie en ColombieBritannique. Quatre-vingt trois pourcent des macreuses marquées suivent deux voies principales vers la zone de reproduction, une route du sud dans l'intérieur des terres comportant des arrêts à Puget Sound et au détroit de Géorgie avec une migration prolongée à l'intérieur des terres et une route côtière du nord caractérisée par de courts déplacements le long de la côte de la Colombie-Britannique et du sud-est de l'Alaska et une migration à l'intérieur des terres débutant au canal de Lynn et les environs. Le choix de route dépend de la latitude du site de nidification dans la forêt boréale du nord du Canada. Des données obtenues d'oiseaux marqués au cours de deux années indiquent une forte fidélité à la route de migration, mais la chronologie de la migration et les sites d'arrêt peuvent changer...

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