Bald eagles remain an iconic symbol of the United States and represent strength, freedom, and wilderness. While bald eagle populations have rebounded remarkably since the 1970s after the banning of DDT and protection under the Endangered Species Act, they still face a variety of threats today.
Habitat Loss
One key threat facing bald eagles is continued habitat loss. Bald eagles typically nest in large trees near water sources, using the same nests year after year. Development near shorelines for homes, businesses, and agriculture removes crucial nesting sites. Eagles are very sensitive to disturbances near their nests and will often abandon a nest if there is too much human activity nearby. Habitat loss not only removes nesting sites but also impacts eagle’s food sources like fish.
Some key statistics on bald eagle habitat loss:
- Over 80% of bald eagle habitat in the lower 48 states lies on private land.
- 90% of nesting bald eagles in the Chesapeake Bay area nest within 1 mile of shorelines.
- 50% of shoreline in the Chesapeake Bay watershed is privately owned.
- From 1998 to 2010, 9% of bald eagle nesting territory was lost to development and land conversion in the Chesapeake Bay.
While the bald eagle population has rebounded overall, the Chesapeake Bay area which once harbored over 1,000 nesting pairs of bald eagles now only has about 350. Continued development near waterways threatens nesting eagles throughout their range.
Lead Poisoning
Another critical ongoing threat is lead poisoning, often from hunters’ ammunition in carcasses and gut piles left in the wild. Bald eagles scavenge on these remains and ingest lead fragments. Lead poisoning can cause mortality, appetite loss, lethargy, and neurological impairment. Some statistics related to lead poisoning in bald eagles:
- A 2021 study found lead exposure in 27% of bald eagles sampled in Pennsylvania.
- A 2019 study found elevated lead levels in the blood of 46% of bald eagles sampled in Iowa.
- Necropsies of bald eagles in Wisconsin from 2012-2018 found lead poisoning to be the most common cause of mortality, accounting for 22% of deaths.
While lead ammunition has been banned for waterfowl hunting since 1991, traditional lead bullets are still commonly used for big game hunting. A ban on lead ammunition for all hunting on state and federal lands would help reduce lead exposure for bald eagles and other scavenging wildlife.
Collisions with Vehicles and Infrastructure
As the bald eagle population has rebounded, increased collisions with cars, trains, and power lines has become a problem in some areas. Juvenile bald eagles in particular are vulnerable as they leave the nest for the first time and may not be adept at avoiding vehicles and infrastructure. Some examples:
- A 2018 study tracked 149 cases of bald eagles killed by vehicle collisions in Minnesota from 2007 to 2018, with an increasing trend over time as the bald eagle population grew.
- Researchers estimate 2,000 to 4,000 bald eagles are killed annually in the U.S. from vehicle hits.
- An estimated 91 bald eagles were killed in collisions with wind turbines at the Altamont Pass Wind Resource Area in California from 2005 to 2010 before measures were taken to reduce collisions.
Mitigation measures like modified infrastructure placement, marking power lines, and roadway signs and lighting can help reduce collisions. But this threat may continue to grow as eagle populations increase and expand into more developed areas.
Other Ongoing Threats
While not as severe as decades ago, contamination from pesticides and other chemicals persists. Eagles may consume fish contaminated with household chemicals, pharmaceuticals, pesticides, and heavy metals from industrial runoff and other sources. The insecticide DEET has also caused eagle mortality in recent years.
Climate change may also pose increasing challenges by impacting bald eagle prey and habitat. Declining winter ice cover, increasing water temperatures, shifting fish populations, drought, and increasing severe weather events could all potentially impact nesting and foraging. However, research is still limited on climate change’s specific effects on bald eagles.
Oil spills remain an acute threat as well, though stricter regulation of oil transportation and storage has reduced impacts in recent decades. Illegal shooting also still claims some eagle lives annually despite their protected status.
While bald eagles no longer teeter on the brink as an endangered species, vigilance is still needed to monitor and address these persistent and emerging threats. With continued conservation efforts, these iconic raptors can continue their incredible recovery across North America.
Table Summarizing Key Ongoing Threats to Bald Eagles
| Threat | Key Facts | Conservation Actions Needed |
|---|---|---|
| Habitat Loss |
|
|
| Lead Poisoning |
|
|
| Collisions |
|
|
| Other Threats |
|
|
Conclusion
While no longer endangered, bald eagles still face a variety of persistent and emerging threats across North America. Habitat loss, lead poisoning, collisions, and contamination remain ongoing challenges for bald eagle conservation. Targeted research, continued environmental regulation, habitat protection, and public awareness can help ensure stable populations of this iconic species into the future.
