The Eagles and the Jets
It wasn’t always this way. At the end of World War II, widespread use of DDT and related chlorinated hydrocarbon pesticides thinned the eggshells of birds such as bald eagles, ospreys and peregrine falcons. Eggs broke during incubation; few eagles hatched, let alone fledged. Eagle populations plunged. The nesting population of bald eagles in the contiguous United States was down to fewer than 400 pairs in 1970.
A focus on environmental law in the 1970s was a boon to the birds. DDT was banned in the early 1970s in Canada and in the United States, and widespread reintroduction efforts resulted in a dramatic change in the birds’ population. Now, as most birdwatchers and hikers know, bald eagles are back from the brink. By 2007 the U.S. federal government was reporting that their population had increased to more than 10,000 pairs, and e very state except Hawaii had nesting bald eagles.
The upsurge continued even after t he U.S. Fish and Wildlife Service removed bald eagles from the Endangered Species Act, shifting them into protection under the Bald and Golden Eagle Protection Act in 2007. (Golden eagles are not as common in the continental United States as bald eagles, but they are distributed widely in the American West, and, much more restrictedly, in the eastern United States.)
There are now at least 13,000 pairs of bald eagles in the country. Pennsylvania, for example, now is home to 200 bald eagle nests; the birds are in 51 of the state’s 67 counties. In the East, at autumn raptor migration watch sites, birdwatchers and hikers also thrill to the sight of bald eagles circling the valleys. Hawk Mountain, near Kempton, Pennsylvania, is especially well known for bald eagle watching, and also during October and November for sightings of the “kings of birds” — golden eagles.
Virginia ’s eagles are also alive and well. According to Virginia’s Center for Conservation Biology at the College of William and Mary:
Bald eagles in Virginia have experienced a dramatic recovery from a low of 30 breeding pairs in the early 1970s to more than 730 pairs in 2011... The Virginia population has now exceeded the recovery goal for the entire Chesapeake Bay. The population has also exceeded the target reproductive rate in every year except one since 1984. However, habitat goals outlined in the Chesapeake Bay recovery plan have not been met and habitat continues to be threatened by human disturbance and development.
Noting the laws that protect this species, and the intense public interest and concern for these charismatic birds, biologists at U.S. airports were finding it difficult to manage eagles. But the pressure to do so is immense. According to the Bird Strike Committee USA, bird and other animal strikes cost U.S. commercial aviation more than $650 million a year. Thus, also in 1970, the U.S. Fish and Wildlife Service issued its proposal to authorize a limited “take” of bald and golden eagles “when they pose a risk to human safety or to the eagles themselves.”
From 1990 to 2011, according to federal data, 146 bald eagles were hit by commercial aircraft in the United States. The mean body mass of a bald eagle is 9.1 lbs (male) to 11.8 lbs (female).
When a danger is declared at a specific airfield, workers are brought in from the agriculture department’s Wildlife Services to scare birds, to capture and relocate immature bald eagles, and to move nests.
Most commercial airports were established before bald eagle populations rebounded. Many such airports are in close proximity, or adjacent to, bays, lakes, rivers and wetlands, which happen to be bald eagle habitats, as the eagles are aquatic oriented birds (they eat fish). One way to help avert potential conflicts is to remove all tall perches that bald eagles might use at and near airports. With federal permission, another possible way of helping is to make sure no bald eagle nests are constructed and used near problem airports. If large, supporting trees are removed, there will not be places were bald eagle nests could be constructed--especially in the eastern US. In the West and Alaska, bald eagles occasionally build ground nests, although this is fairly rare.
If bald eagles still visit problem airports, then the only alternative might appear to be live-trapping and relocation. Advocates have spoken out against this disturbance to bald eagles; yet as the human population continues to grow, this dilemma isn’t going away any time soon.
Where to Watch Eagles
Because bald eagles are now so numerous through many parts of the United States and Canada, recreational eagle watching is increasingly popular—and not only during spring and autumn at well-known raptor migration watch sites, but also at other locations during other seasons of the year. Here are a few of the best places to watch bald eagles in the continental United States. (Note: you must keep your distance, and keep quiet, so as not to disturb the birds. Never approach or disturb a nest.)
• Alaska Chilkat Bald Eagle Preserve (near Haines). The mid-November Alaska Bald Eagle Festival is ideal, with as many as 3,000 eagles feeding on salmon of five species
• Connecticut River Eagle Festival (in Essex) on Presidents’ Day weekend in mid-February.
• Various locks and dams along the Upper Mississippi River during winter.
• Bear River Migratory Bird Refuge (near Brigham City, Utah) in early December, and February and March. • Skagit River Bald Eagle Natural Area (near Rockport, Washington) from late December to mid-February. Catch the Upper Skagit Bald Eagle Festival in Rockport.
References and Additional Reading
D. A. Buehler, “Bald Eagle (Haliaeetus leucocephalus)” in The Birds of North America No. 506. (A. Poole and F. Gill, eds., 2000). The Birds of North America, Inc., Philadelphia, PA.
Jerry Feaser, The Growing and Prominent Presence of Pennsylvania’s bald eagles. Pennsylvania Game Commission News Release #072-12 (27 June 2012).
Donald S. Heintzelman, Hawks and Owls of Eastern North America. Rutgers University Press (2004).
Donald S. Heintzelman, Guide to Hawk Watching in North America. Globe Pequot Press (2004).
Sandra E. Wright, Bald Eagles: A Threatened Species Becomes a Threat to Aviation. Proceedings of the 2007 Bird Strike Committee USA/Canada (9 th Annual Meeting, Kingston, Ontario). Available: http://digitalcommons.unl.edu/birdstrike2007/16/
About the author: Donald S. Heintzelman is a professional ornithologist with a special interest in raptors, and is the author of 22 published books. He has more than 50 years field experience studying raptors, tundra swans and other wildlife throughout the world. He lives in the rural countryside in southeastern Pennsylvania.