Why Bald Eagle Populations Soared in the Last Decade

The once dwindling bald eagle population that brought the raptor close to extinction in the United States has soared in the past decade, according to a new report by the U.S. Fish and Wildlife Service (USFWS). Eagle populations quadrupled in size since 2009 with 316,700 individual bald eagles spotted and 71,400 nesting pairs recorded during the 2019 breeding season, reports Lauren M. Johnson and Liz Stark for CNN.

In 2009, there were 72,434 individual bald eagles and just 30,548 nesting pairs, reports Sophie Lewis for CBS. The current eagle population was estimated through aerial surveys conducted in the lower 48 states by migratory bird biologists from 2018 to 2019, reports CBS. The surveys tracked eagle nesting areas and counted nesting territories. The researchers collaborated with the Cornell Lab of Ornithology and used bald eagle data from the citizen science app eBird to collect data in areas where aerial surveys could not be conducted. The surveys and eBird data were combined with survival, productivity, and breeding rates to estimate the total bald eagle population.

Through eBird, about 180,000 birdwatchers recorded bald eagle sightings, reports Anna M. Phillips for the Los Angeles Times. The USFWS is using the app as a new method to track bird data, where traditionally only surveys were used. It's possible the additional data crowdsourced on eBird partially accounts for the recent surge in population numbers. However, Brian Millsap, the USFWS national raptor coordinator, says that the data estimates line up with other survey data as well, the LA times reports.

"While the eBird data has improved the estimates, the vast majority of this increase really is attributed to bald eagle population growth," Millsap told the LA Times.

Bald eagle populations have been steadily recovering since their all-time low in the 1960s when fewer than 500 nesting pairs were left. Raptor populations severely declined between 1870 and 1970 due to habitat loss, hunting and use of the pesticide DDT during World War II. In 1967, bald eagles were placed on the threatened and endangered species list.

Extensive conservation efforts from breeding programs and habitat protection around the raptors' nesting sites aided in the population's recovery. Decades of protection through the Endangered Species Act enacted in 1973 and banned usage of DDT in 1972 allowed eagle populations to flourish. In 2007, the bald eagle was removed from the endangered list, but the species is still protected by the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act.

"This is truly a historic conservation success story. The bald eagle has always been considered a sacred species to American Indian people, and similarly, it's sacred to our nation. The strong return of this treasured bird reminds us of our nation's shared resilience and the importance of being responsible stewards of our lands and waters that bind us together," said U.S. Secretary of the Interior Deb Haaland in a news briefing, according to CNN.

Elizabeth Gamillo | | READ MORE

Elizabeth Gamillo is a correspondent for Smithsonian and a science journalist based in Milwaukee, Wisconsin. She has written for Science magazine as their 2018 AAAS Diverse Voices in Science Journalism Intern.