Bald Eagle Migration, Why is it Important?

Recent advances in lightweight transmitter technology called satellite telemetry have begun to help scientists better understand the migration patterns of the bald eagle.  Tagging small populations of bald eagles can more readily gather useful information such as the ecology of bald eagles and the life of history of bald eagles.  Observers have also been able to determine the entire migration schedule over the course of a full year and found the bald eagles are very consistent travelers.

In one study done by the University of California, a group of bald eagles were tagged near Fresno to determine their migratory pattern.   Almost every eagle that was tracked using transmitters traveled north from their winter home in the Millerton Lake, California area and journeyed thousands of kilometers to a relatively quiet area of Canada's Northwest Territories, northern Alberta, and Saskatchewan.  Remarkably, the return paths to California taken by these eagles in the spring were nearly identical to the routes that brought them North to Canada in the fall.  But, why is it important for us to know about bald eagles migration?

Bald eagles migrate, as all migrating birds do, to find surroundings that are more hospitable during wintertime.  In addition, they migrate to places where they're more likely to find sufficient food.  In the spring, they travel again to a familiar, comfortable area to nest and breed.  Typically, the bald eagle raises its young very near to where it was born.  When we see differences in the migratory paths, nesting and wintering locations of bald eagles what we are really seeing are the differences in their habitat.

In 1963, the number of bald eagle pairs in the lower 48 United States was just over 400.  Although we have seen that number grow by a factor of 20 since that time, deforestation and urbanization, are gradually eroding viable breeding and wintering locations for the species virtually leaving them homeless.  In the Washington, DC area, we are beginning to observe changes in the migratory pattern of the bald eagle telling us that something is wrong with the land.  Leading experts believe that a primary cause for the changes in migration patterns is the density of population quickly growing along the shoreline of the Chesapeake Bay.  Ironically, just as the rising number has prompted the federal government to begin proceedings to remove the bald eagle from the endangered species list, leading scientists are deeply concerned that the overdevelopment of such a key eagle habitat in Washington's backyard could keep the species forever etched on that list.