- Habitat destruction: The destruction of forests and other natural habitats has reduced the amount of suitable nesting and foraging sites for eagles.
- Hunting and persecution: Eagles have been hunted for their feathers, meat, and other body parts and even as predators by ranchers and farmers.
- Pollution: Pesticides, herbicides, and other pollutants can accumulate in the food chain and poison eagles.
- Disease: A disease called West Nile virus has killed more than a million birds in the U.S. since 1999, including a significant number of eagles.
Here are some additional specific examples of how these factors have affected eagle populations:
- California condors: California condors were once widespread in western North America. Still, their population declined dramatically due to hunting, habitat destruction, and poisoning. They were declared extinct in the wild in 1987, but a captive breeding program has successfully reintroduced them to several areas.
- Bald eagles: Bald eagles were once common throughout North America. Still, their population declined drastically due to DDT poisoning, hunting, and habitat destruction. Their population is gradually rebounding as DDT was banned in the U.S. in 1972, and laws were passed to protect them.
- Golden eagles: Golden eagles are widespread in North America, Europe, and Asia. Their population is relatively stable but is threatened by habitat destruction, hunting, and poisoning.