For hundreds of years, bald eagle numbers in the U.S. plummeted due to habitat destruction and, in the 20th century, the introduction of poisonous pesticides. Now, conservationists are welcoming the sights of new nesting grounds, and people across the country are spotting more of the majestic birds flying overhead as the numbers finally recover.

Patti Barber, a Pennsylvania Game Commission biologist, said that she feels rewarded for the fight to bring back the endangered species. “It’s hard to step away from the fact that they are our nation’s symbol and knowing that they’ve now come back from the brink,” she said. “I think a lot of people have a lot of pride that we managed to do that.”

The bald eagle was adopted as the symbol for the newly-formed United States of America in 1782. At that point, the country may have been home to as many as 100,000 nesting eagles. The first major decline of their numbers was noted in the mid-1800s, in conjunction with the disappearance of prey such as waterfowl and shorebirds. The decline was likely linked to habitat destruction, as humans felled tall nesting trees and polluted rivers and lakes, which act as the eagles’ food sources.

The biggest blow to the bald eagle population came after World War II, when the introduction of the pesticide DDT caused a rapid decline. The eagles became exposed to the pesticide through food sources like fish, and the presence of DDT in their diet caused often fatal reproductive issues. Ingesting the pesticide thinned the eagles’ eggshells and caused them to break easily, which meant that few bald eagle chicks made it past infancy. The use of DDT in the U.S. was banned in 1972, but the measure seemed to come too late: six years later, bald eagles were listed as an endangered species in 43 states.

After years of fighting to clean habitats and keep the birds alive, the birds finally dropped from the ranks of endangered species in the 1990s. Now, 69,000 bald eagles fly across the United States, up from as few as 487 nesting pairs in 1963.

However, new dangers hide in store for the recovering species: Lisa Smith, head of the Tri-state Bird Rescue and Research Inc., said that bald eagles are now competing for space and inflicting wounds on one another. Some birds are solving the problem by nesting in residential areas. “As the population has increased over the past 20 years, the amount of suitable habitat for bald eagles to breed in has decreased,” said Smith.