Inclement weather and American woodcock building collisions during spring migration

Weather appears to influence collisions of migratory birds with human-built structures including buildings, but formal analyses are lacking. In 2018, as part of a two-year study at 21 buildings in Minneapolis, Minnesota, USA, we observed a large number of American woodcock Scolopax minor collisions during two early spring snowstorms. We describe these events, analyze associations between weather and woodcock collisions during spring 2018, and compare observations to past studies across the woodcock's range. Most spring 2018 woodcock collisions (11 of 15; 73.3%) occurred in association with the two snowstorms. Analyses indicated collisions were positively associated with maximum and average wind speeds the night before collision surveys, and most collisions occurred with north winds. Collisions also increased with lower cloud base height two nights before surveys. These results support that woodcock collisions were greatly influenced by inclement weather, specifically the coincidence of strong north wind and low clouds. Comparing results to past studies illustrates that building collisions could be a major range-wide source of woodcock mortality, especially in spring migration when mortality is likely additive. Although more research is needed to understand range-wide, population-level effects of woodcock collisions, management to reduce building collisions during migration may benefit woodcock populations. Additional research is needed to clarify effects of weather on bird collisions because management efforts could be refined if collisions of woodcocks and other bird species were forecastable like the weather.