More than 316,000 bald eagles live in the lower 48, according to a new estimate

Over the past 50 years, the U.S. Fish and Wildlife Service has compiled a number of state bald eagle nests and airplane surveys to track the population’s triumphant recovery from America’s national symbol. However, in its new Bald Eagle Population Report, tabulated using results using eBird data from the Cornell Lab of Ornithology, the USFWS found many more eagles than previously thought in the lower 48 states.

A lot more.

The bald eagle population estimate for the lower 48 states has quadrupled since 2009 thanks to a recovery in the population and new eBird estimation methods. Photo by Randy Walker / Macaulay Library, graphic by Jillian Ditner.

The latest USFWS Bald Eagle Population Update report estimates 316,708 eagles in the contiguous United States, which is more than four times the eagle population reported in the 2009 report. The rising number of bald eagles undoubtedly reflects the ongoing success story of conservation, which dates back to the 1972 ban on DDT. However, it also represents a major advancement in the use of civic science-powered supercomputing to generate better estimates for the eagle population.

“Working with Cornell to integrate data from our aerial photography with eBird data on the relative abundance of bald eagles is one of the most impressive approaches we’ve looked at in civic science programs,” said Jerome Ford, associate director of the USFWS program for migratory birds. “This important information has been essential to fully assessing the bald eagle population in the contiguous United States and we look forward to working with Cornell in the future.”

Bald eagle numbers have rebounded from a 1963 low of 417 nests following the elimination of DDT, the Endangered Species Act (ESA) protection, and dedicated conservation efforts. Bald eagle photos via the Macaulay Library: on Bill Wood’s nest; in flight by Eric Heisey. Artwork by Jillian Ditner.

The new USFWS report estimates that 71,467 breeding pairs of bald eagles nest in the lower 48 states, double the number of eagle nests recorded in the 2009 report – and a number higher than the all-time low of 417 known eagle nests in the Year 1963. Back then, the popular use of DDT pesticides after World War II had decimated the eagle population. In 1967 the bald eagle received protection under the predecessor of the Federal Act on Endangered Species. In 1972 the United States banned DDT.

Thanks to legal protection (the bald eagle was a founding member of what would later become the ESA, which was incorporated into law in 1973), captive breeding programs, and protection of the habitat around nests, the bald eagle population recovered. The USFWS tracked the recovery through aerial photography every few years as pilots of the Eagle Counting Mission Agency’s migratory bird program flew over high density eagle breeding areas to count the number of occupied nests. For this latest USFWS report, the federal government partnered with Cornell Lab for the first time to augment their aerial photography with an eBird-generated big data population model.

The computer science that developed the eBird Model was based on Citizen Science – more than 180,000 bird watchers who shared data with the Cornell Lab by uploading eBird checklists (details of which species of birds they saw in a single excursion and how many ). Cornell Lab scientists then developed a model that uses eBird estimates of the relative abundance of bald eagles to generate a number of occupied nesting areas in the areas that USFSWS was unable to cover in its aerial photographs.

“One of our primary goals was to see if population modeling based on eBird data would improve the survey work of the Fish and Wildlife Service,” said Viviana Ruiz-Gutierrez, associate director of the Cornell Lab Center for Avian Population Studies, who oversees the survey performed the role of the laboratory in this partnership. “We hope this will allow the fish and wildlife service to track bald eagle populations in a much larger area in the most cost-effective manner in the future.”

And Ruiz-Gutierrez also hopes that these eagle models will continue to show positive momentum. Since the USFWS delisted the bald eagle in 2007 – a historic moment for ESA species restoration – the number of known occupied nests in the lower 48 states has more than doubled, according to this latest report from eBird Models.

“It’s a great American conservation success story,” said Amanda Rodewald, Cornell Lab’s senior director for bird population studies, at a virtual press conference hosted by the USFWS today. She thanked the agency for hosting the event to celebrate the recovery of the eagles and to celebrate the role of citizen science – the thousands of bird watchers who shared their observations to help build population models.

“It is encouraging to see how we can all come together in different ways to preserve the birds we all value,” Rodewald said. “At Cornell Lab, we hope this is just the beginning of many more successful collaborations with the fish and wildlife service.”

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