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We discuss select imprecise and untenable natural history information about migration, urban habitat use, and diet presented in the technical literature about Accipiter hawks in North America. We focus primarily on challenging the claim that Sharp-shinned Hawks (Accipiter striatus) are more frequent predators of House Sparrows (Passer domesticus) than are Cooper's Hawks (A. cooperii). We urge scientists to be cognizant of the ever-changing dynamics of the predatory behavior, nesting, and migration ecology of Sharp-shinned and Cooper's hawks due to anthropogenic factors, features that are in constant flux and may not be well tracked long term or apply to the entire distributional ranges of these 2 species. Discutimos acerca de informaciones de historia natural imprecisa e insostenible acerca de la migración, del uso de hábitat urbano y la dieta presentada en la literatura técnica sobre gavilanes Accipiter en América del Norte. Principalmente nos enfocamos en cuestionar la afirmación de que el gavilán americano (Accipiter striatus) es un depredador más frecuente de gorrión común (Passer domesticus) que del gavilán de Cooper (A. cooperii). Exhortamos a los científicos a reconocer las dinámicas siempre cambiantes de comportamientos de depredación, anidamiento y ecología migratoria del gavilán americano y del gavilán de Cooper debido a factores antropogénicos, aspectos que están en flujo constante y podrían no tener buen seguimiento a largo plazo o no aplicar al rango de distribución completo de esas especies. Palabras clave: depredación, dieta, gorrión común, migración, urbanización. [ABSTRACT FROM AUTHOR]

House Sparrow (Passer domesticus) populations declined across much of their global range in the late 20th century. Most research examining this decline is conducted in the species' native European range, but Europe encompasses a small portion of the species' current distribution. House Sparrow population trends in the United States and Canada, and the potential mechanisms driving these trends, remain relatively unexplored. We use 21 years of data from Project FeederWatch, a large-scale citizen science project, to investigate House Sparrow population trends in North America. We found winter flocks in urbanized areas were larger than flocks in rural areas, with widespread spatial heterogeneity in local population trends. Despite greater abundance in developed areas, House Sparrow populations declined in developed areas from 1995 to 2016 while remaining stable in rural areas. House Sparrow population declines coincide with an increase in populations and expansion of the winter distributions of Accipiter hawks, which are known predators of House Sparrows. However, we do not find a direct connection between the presence of Accipiter hawks at count sites and House Sparrow population declines in winter. These results expand our knowledge of widespread House Sparrow declines to North America and provide context for continuing research on House Sparrow declines in the introduced range. [ABSTRACT FROM AUTHOR]

West Nile virus (WNV) has been maintained in North America in enzootic cycles between mosquitoes and birds since it was first described in North America in 1999. House sparrows (HOSPs; Passer domesticus) are a highly competent host for WNV that have contributed to the rapid spread of WNV across the U.S.; however, their competence has been evaluated primarily using an early WNV strain (NY99) that is no longer circulating. Herein, we report that the competence of wild HOSPs for the NY99 strain has decreased significantly over time, suggesting that HOSPs may have developed resistance to this early WNV strain. Moreover, recently isolated WNV strains generate higher peak viremias and mortality in contemporary HOSPs compared to NY99. These data indicate that opposing selective pressures in both the virus and avian host have resulted in a net increase in the level of host competence of North American HOSPs for currently circulating WNV strains. Author Summary: West Nile virus (WNV) emerged in North America in 1999 and rapidly spread across the U.S. due to the presence of highly susceptible mosquito vectors and avian hosts. One of the major avian reservoirs for WNV in the U.S. is the house sparrow (HOSP), which has low mortality during WNV infection. Here, we investigate how the response of wild HOSPs to WNV infection has changed as a result of the 15-year history of WNV circulation in the U.S. In addition, we evaluated the impact of WNV evolution on viral infection in HOSPs and report that WNV has become increasingly pathogenic to HOSPs over time, while HOSPs may have developed resistance to early WNV strains. Thus, HOSPs are still likely to be an important avian reservoir for WNV in the U.S., and WNV has adapted to its avian hosts during emergence in North America. [ABSTRACT FROM AUTHOR]

In North America, nest site competition from invasive cavity-nesting birds can limit the opportunities for successful nesting by native birds. Managing invasive species is costly and complex, requiring input from biologists, decision makers, and the public. An informed and engaged public can play an important role in mitigating the negative effects of invasive avian species. However, little is known regarding the publics' knowledge, attitudes, and behaviors toward non-native bird species. We examined the association between participating in a citizen science project and enjoyment, knowledge, and management of two non-native avian species in North America: European starlings (Sturnus vulgaris) and house sparrows (Passer domesticus). We administered a pre and post survey to 947 people who monitor nest boxes in the United States and Canada, 30% of whom were also reporting their observations to NestWatch, a citizen science project focused on nesting birds. We found that NestWatch participants were more likely to have negative views of non-native species, score higher on bird identification tasks, and manage for invasive species than non-participants. The most important predictor for undertaking management activities was respondents' perceptions of whether they believed non-native birds to be a problem at the continental scale, underscoring the important role of individual factors such as perception. Our study also highlights the important role citizen science may play in shaping attitudes and behaviors and increasing knowledge. We propose a conceptual model describing the mechanisms by which citizen science can be leveraged for management of invasive species. • Understanding public attitudes, knowledge, and behaviors is necessary for managing invasive species. • Email intervention campaigns had little effect on increasing knowledge of invasive species. • Citizen scientists had more polarized views of invasive species than non-participants. • Citizen scientists were more likely to manage for invasive species than non-participants. • Citizen science may be a model system for managing invasive avian species. [ABSTRACT FROM AUTHOR]