Mapping bald eagle movement corridors in the Northeast
September 29, 2016
By Bryan Watts, Center for Conservation Biology
With the establishment of many commercial-scale wind installations throughout the eastern United States and Canada has come a growing concern about the potential impact to migrating eagles. Raptor migration corridors form around narrow ridgetops and coastlines that produce updrafts the birds use to facilitate soaring and gliding. These same sites support the best wind profiles for commercial wind power generation. Development of turbine fields within migration routes has the potential to cause population-level impacts. One of the most effective strategies for reducing eagle and other raptor mortalities is to place turbines away from areas of high activity. An impediment to implementing this strategy has been our inability to identify movement corridors.
In a recent paper published in Plos One, CCB biologists used satellite tracking data to delineate eagle migration corridors in the Northeast and overlay these corridors on maps of existing wind facilities and areas of viable wind-energy development. A dynamic Brownian bridge movement model was used to process 132 individual migration tracks to create a utilization surface that delineated the movement corridors. The work was funded by the American Wind Wildlife Institute and the U.S. Fish and Wildlife Service with the intent of informing the placement of future wind facilities in the Northeast.
Delineation of the movement corridors will be important for future wind development. More than 2,000 existing wind turbines were within the highest two categories of eagle use. However, only 6% of the area supporting the most commercially viable wind power classes overlapped with these eagle use areas, suggesting that a great many locations exist where wind may be captured outside of eagle movement areas.