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1. Assessing the combined threats of artificial light at night and air pollution for the world’s nocturnally migrating birds

   https://doi.org/10.1111/geb.13466  

   La Sorte, Frank A. ; Aronson, Myla F. J. ; Lepczyk, Christopher A. ; Horton, Kyle G. ; Sheard, ed., Catherine ( February 2022 , Global Ecology and Biogeography)

   Two important environmental hazards for nocturnally migrating birds are artificial light at night (ALAN) and air pollution, with ambient fine particulate matter (PM_2.5) considered to be especially harmful. Nocturnally migrating birds are attracted to ALAN during seasonal migration, which could increase exposure to PM_2.5. Here, we examine PM_2.5concentrations and PM_2.5trends and the spatial correlation between ALAN and PM_2.5within the geographical ranges of the world’s nocturnally migrating birds.

   Global.

   1998–2018.

   Nocturnally migrating birds.

   We intersected a global database of annual mean PM_2.5concentrations over a 21‐year period (1998–2018) with the geographical ranges (breeding, non‐breeding and regions of passage) of 225 nocturnally migrating bird species in three migration flyways (Americas,n = 143; Africa–Europe,n = 36; and East Asia–Australia,n = 46). For each species, we estimated PM_2.5concentrations and trends and measured the correlation between ALAN and PM_2.5, which we summarized by season and flyway.

   Correlations between ALAN and PM_2.5were significantly positive across all seasons and flyways. The East Asia–Australia flyway had the strongest ALAN–PM_2.5correlations within regions of passage, the highest PM_2.5concentrations across all three seasons and the strongest positive PM_2.5trends on the non‐breeding grounds and within regions of passage. The Americas flyway had the strongest negative air pollution trends on the non‐breeding grounds and within regions of passage. The breeding grounds had similarly negative air pollution trends within the three flyways.

   The combined threats of ALAN and air pollution are greatest and likely to be increasing within the East Asia–Australia flyway and lowest and likely to be decreasing within the Americas and Africa–Europe flyways. Reversing PM_2.5trends in the East Asia–Australia flyway and maintaining negative PM_2.5trends in the Americas and Africa–Europe flyways while reducing ALAN levels would likely be beneficial for the nocturnally migrating bird populations in each region.

    

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2. Seasonal associations with urban light pollution for nocturnally migrating bird populations

   https://doi.org/10.1111/gcb.13792  

   La Sorte, Frank A. ; Fink, Daniel ; Buler, Jeffrey J. ; Farnsworth, Andrew ; Cabrera‐Cruz, Sergio A. ( July 2017 , Global Change Biology)

   The spatial extent and intensity of artificial light at night (ALAN) has increased worldwide through the growth of urban environments. There is evidence that nocturnally migrating birds are attracted toALAN, and there is evidence that nocturnally migrating bird populations are more likely to occur in urban areas during migration, especially in the autumn. Here, we test if urban sources ofALANare responsible, at least in part, for these observed urban associations. We use weekly estimates of diurnal occurrence and relative abundance for 40 nocturnally migrating bird species that breed in forested environments in North America to assess how associations with distance to urban areas andALANare defined across the annual cycle. Migratory bird populations presented stronger than expected associations with shorter distances to urban areas during migration, and stronger than expected association with higher levels ofALANoutside and especially within urban areas during migration. These patterns were more pronounced during autumn migration, especially within urban areas. Outside of the two migration periods, migratory bird populations presented stronger than expected associations with longer distances to urban areas, especially during the nonbreeding season, and weaker than expected associations with the highest levels ofALANoutside and especially within urban areas. These findings suggest thatALANis associated with higher levels of diurnal abundance along the boundaries and within the interior of urban areas during migration, especially in the autumn when juveniles are undertaking their first migration journey. These findings support the conclusion that urban sources ofALANcan broadly effect migratory behavior, emphasizing the need to better understand the implications ofALANfor migratory bird populations.

    

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3. The role of artificial light at night and road density in predicting the seasonal occurrence of nocturnally migrating birds

   https://doi.org/10.1111/ddi.13499  

   La Sorte, Frank A. ; Johnston, Alison ; Rodewald, Amanda D. ; Fink, Daniel ; Farnsworth, Andrew ; Van Doren, Benjamin M. ; Auer, Tom ; Strimas‐Mackey, Matthew ; López, ed., Ana Benítez ( March 2022 , Diversity and Distributions)

   Artificial light at night (ALAN) and roads are known threats to nocturnally migrating birds. How associations with ALAN and roads are defined in combination for these species at the population level across the full annual cycle has not been explored.

   Western Hemisphere.

   We estimated range‐wide exposure, predictor importance and the prevalence of positive associations with ALAN and roads at a weekly temporal resolution for 166 nocturnally migrating bird species in three orders: Passeriformes (n = 104), Anseriformes (n = 27) and Charadriiformes (n = 35). We clustered Passeriformes based on the prevalence of positive associations.

   Positive associations with ALAN and roads were more prevalent for Passeriformes during migration when exposure and importance were highest. Positive associations with ALAN and roads were more prevalent for Anseriformes and Charadriiformes during the breeding season when exposure was lowest. Importance was uniform for Anseriformes and highest during migration for Charadriiformes. Our cluster analysis identified three groups of Passeriformes, each having similar associations with ALAN and roads. The first occurred in eastern North America during migration where exposure, prevalence, and importance were highest. The second wintered in Mexico and Central America where exposure, prevalence and importance were highest. The third occurred throughout North America where prevalence was low, and exposure and importance were uniform. The first and second were comprised of dense habitat specialists and long‐distance migrants. The third was comprised of open habitat specialists and short distance migrants.

   Our findings suggest ALAN and roads pose the greatest risk during migration for Passeriformes and during the breeding season for Anseriformes and Charadriiformes. Our results emphasise the close relationship between ALAN and roads, the diversity of associations dictated by taxonomy, exposure, migration strategy and habitat and the need for more informed and comprehensive mitigation strategies where ALAN and roads are treated as interconnected threats.

    

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4. Continental‐scale biomass redistribution by migratory birds in response to seasonal variation in productivity

   https://doi.org/10.1111/geb.13460  

   Ng, Wee Hao ; Fink, Daniel ; La Sorte, Frank A. ; Auer, Tom ; Hochachka, Wesley M. ; Johnston, Alison ; Dokter, Adriaan M. ; Storch, ed., David ( February 2022 , Global Ecology and Biogeography)

   Animal migration is often explained as the result of resource tracking in seasonally dynamic environments. Therefore, resource availability should influence both the distributions of migratory animals and their seasonal abundance. We examined the relationship between primary productivity and the spatio‐temporal distributions of migratory birds to assess the role of energy availability in avian migration.

   North America.

   Full annual cycle, 2011–2016.

   Nocturnally migrating landbirds.

   We used observations of nocturnally migrating landbirds from the eBird community‐science programme to estimate weekly spatial distributions of total biomass, abundance and species richness. We related these patterns to primary productivity and seasonal productivity surplus estimated using a remotely sensed measure of vegetation greenness.

   All three avian metrics showed positive spatial associations with primary productivity, and this was more pronounced with seasonal productivity surplus. Surprisingly, biomass showed a weaker association than did abundance and richness, despite being a better indicator of energetic requirements. The strength of associations varied across seasons, being the weakest during migration. During spring migration, avian biomass increased ahead of vegetation green‐up in temperate regions, a pattern also previously described for herbivorous waterfowl. In the south‐eastern USA, spring green‐up was instead associated with a net decrease in biomass, and winter biomass greatly exceeded that of summer, highlighting the region as a winter refuge for short‐distance migrants.

   Although instantaneous energy availability is important in shaping the distribution of migratory birds, the stronger association of productivity with abundance and richness than with biomass suggests the role of additional drivers unrelated to energetic requirements that are nonetheless correlated with productivity. Given recent reports of widespread North American avifaunal declines, including many common species that winter in the south‐eastern USA, understanding how anthropogenic activities are impacting winter bird populations in the region should be a research priority.

    

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5. Enhancing Accuracy of Air Quality and Temperature Forecasts During Paddy Crop Residue Burning Season in Delhi Via Chemical Data Assimilation

   https://doi.org/10.1029/2020JD033019  

   Kumar, Rajesh ; Ghude, Sachin D. ; Biswas, Mrinal ; Jena, Chinmay ; Alessandrini, Stefano ; Debnath, Sreyashi ; Kulkarni, Santosh ; Sperati, Simone ; Soni, Vijay K. ; Nanjundiah, Ravi S. ; et al ( August 2020 , Journal of Geophysical Research: Atmospheres)

   This paper examines the accuracy of Weather Research and Forecasting model coupled with Chemistry (WRF‐Chem) generated 72 hr fine particulate matter (PM_2.5) forecasts in Delhi during the crop residue burning season of October‐November 2017 with respect to assimilation of the Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) retrievals, persistent fire emission assumption, and aerosol‐radiation interactions. The assimilation significantly pushes the model AOD and PM_2.5toward the observations with the largest changes below 5 km altitude in the fire source regions (northeastern Pakistan, Punjab, and Haryana) as well as the receptor New Delhi. WRF‐Chem forecast with MODIS AOD assimilation, aerosol‐radiation feedback turned on, and real‐time fire emissions reduce the mean bias by 88–195 μg/m³(70–86%) with the largest improvement during the peak air pollution episode of 6–13 November 2017. Aerosol‐radiation feedback contributes ~21%, ~25%, and ~24% to reduction in mean bias of the first, second, and third days of PM_2.5forecast. Persistence fire emission assumption is found to work really well, as the accuracy of PM_2.5forecasts driven by persistent fire emissions was only 6% lower compared to those driven by real fire emissions. Aerosol‐radiation feedback extends the benefits of assimilating satellite AOD beyond PM_2.5forecasts to surface temperature forecast with a reduction in the mean bias of 0.9–1.5°C (17–30%). These results demonstrate that air quality forecasting can benefit substantially from satellite AOD observations particularly in developing countries that lack resources to rapidly build dense air quality monitoring networks.

    

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