Community-science reveals delayed fall migration of waterfowl and spatiotemporal effects of a changing climate

Climate change has well-documented, yet variable, influences on the annual
movements of migratory birds. The effects of climate change on fall
migration remains understudied compared to spring, but appears to be less
consistent among species, regions, and years. Changes in the pattern and
timing of waterfowl migration in particular may result in cascading
effects on ecosystem function, and socioeconomic and cultural outcomes. We
investigated changes in the migration of 15 waterfowl species along a
major flyway corridor of continental importance in northeastern North
America using 43 years of community-science data. We built spatially- and
temporally-explicit hierarchical generative additive models for each
species and demonstrated that climate, specifically the interaction
between minimum temperature and precipitation, significantly influences
migration phenology for most species. Certain species’ migratory movements
responded to specific temperature thresholds (climate migrants) and others
reacted more to the interaction of temperature and precipitation (extreme
event migrants). There are already significant changes in the fall
migration phenology of common waterfowl species with high ecological and
economic importance, which may simply increase in the context of a
changing climate. If not addressed, climate change could induce mismatches
in management, regulations, and population surveys which would negatively
impact the hunting industry. Our findings highlight the importance of
considering species-specific spatiotemporal scales of effect on climate on
migration and our methods can be widely adapted to quantify and forecast
climate-driven changes in wildlife migration.