Toward integrating citizen science and radar data for migrant bird conservation

Migrating birds face an array of challenging conditions and hazards during their annual movements, including novel threats of mortality from anthropogenic structures, such as wind energy turbines and buildings. There is a need for new data sources that can be used to create risk assessments across a wide range of spatial and temporal scales, and weather radar data have shown promise in this regard. A primary limitation on the use of weather radar data in macroscale ecology has been the difficulty in data access and processing to make real-time assessments, and the lack of species-level information. We compared two weather radar products, Level II and UNQC-CREF that differ in several aspects. We found the 2D UNQC-CREF product provides similar information to Level II data regarding spatial and temporal patterns of bioscatter, although not without caveats. Due to its rapid availability and ease of use, we combined UNQC-CREF data with eBird daily species counts to quantify autumnal migration along one of North America's major migratory routes. During their autumn migration southward, we predicted birds would use prevailing winds and favorable atmospheric conditions to time their migratory movements. Wind direction and ordinal date were strong predictors as were variables associated with inclement weather, including barometric pressure and ambient temperature. These patterns suggest that at a coarse scale, migratory birds avoid headwinds during their southerly movements during autumn, and more broadly indicate that local weather conditions can be used to predict pulses of migratory activity in the aerosphere. Our results suggest that similar methods could be used to measure the temporal and spatial components of avian migration at greater spatial scales - providing crucial information for conservation and management for migratory faunas. Specifically, future algorithms should focus on real-time implementation for bird strike mitigation, by altering wind energy facility operation on nights of peak migratory flow, in addition to timing lights-out events to minimize collisions with existing infrastructure such as buildings.