The United States Fish and Wildlife Service (USFWS) has just released data on bald eagle nests and productivity in the Upper Mississippi River National Wildlife and Fish Refuge (Upper Miss Refuge). This Refuge begins at the base of Lake Pepin and stretches 260 miles down the Mississipi River to Rock Island, IL. The USFWS has been collecting data on active bald eagle nests and nest productivity on for decades. In 1963, there was just one active bald eagle nest along the entire 260 mile Upper Mississippi Refuge.
In 2012, the number of active bald eagle nests on the Refuge (313) was significantly higher than the previous year (283) and productivity at these nest was also up; 1.49 young/nest in 2012 vs. 1.28 young/nest in 2011.
These numbers are consistent with the steady rise in bald eagle numbers and productivity seen over the last 3 decades. Nearly forty years ago, the bald eagle was placed on the Endangered Species list because population numbers in the United States had dropped so low. In 1972, there were only an estimated 400 nesting pairs across the entire lower 48 states. The banning of DDT and stronger protection of bald eagle habitat and nesting areas contributed to the successful recovery of the bald eagle. In 2007, the bald eagle was officially removed from the list of endangered species.
Population and productivity numbers from the Upper Miss Refuge over the decades tell the story of this recovery. In 1986, just nine nests on the Refuge produced an average on just one fledgling per nest. Ten years later in 1996, both the number of nests and the productivity had risen to 62 nests producing 91 fledgling bald eagles. By 2006, bald eagles had 165 active nests on the Upper Miss Refuge and more than 285 young were produced in that season alone.
Bald eagles take approximately five years to reach maturity and breeding age. During these first few years, young eagles face many threats. In fact, only about 50% of eaglets that hatch will survive through the year. Another 20-30% may not reach breeding age. So, nest productivity is an important factor in ensuring the long-term health of the population.