​Fall V. Spring Migration Stopover Density in Georgia

​Thanks to a generous grant from the Disney Conservation Fund, Birds Georgia has been working with Dr. Kyle Horton at Colorado State University (CSU) to measure migratory bird activity over the state during spring and fall migration. These maps were the result of that work.

Each fall and spring, billions of migratory birds travel across North America making their way between breeding grounds and wintering grounds. These birds must constantly confront changes to the landscapes below caused by natural and man-made forces, including the rapid proliferation of brightly lit nighttime landscapes. 

While migration takes part in the skies, birds must stop along the way to rest and refuel. Birds Georgia wants to know WHERE these birds are stopping and to gain a better understanding of WHY they choose these locations. 

By pairing migration intensity measurements from nearby weather stations with other environmental variables, the CSU team was able to train a machine learning model that predicted migration intensity in Georgia during spring and fall from 2000 to 2020. With these predictions, they were able to establish regions considered hotspots of bird migration stopover and refueling. The darker areas on the maps represent higher concentrations of birds stopping over to rest and feed.

In over 70% of the models that were created, skyglow (or night time lighting) was identified as a highly influential and consistently positive predictor of bird migration stopover density across Georgia and the United States.

The findings of this study point to the ever-expanding threat that brightly lit night skies pose to birds, particularly during migration. In short, migratory birds are extremely sensitive to nighttime lighting which acts like a magnet pulling them into brightly lit areas and cities where they face threats ranging from building collisions to predation. 

In recent years,  the Colorado State Team has been working with state organizations, like Birds Georgia, to provide state-level migration forecasts enabling us to issue Lights Out alerts on nights of peak migratory bird activity.

Learn more about this project or view the nightly forecast for Georgia enabled by this technology on our website.