Northern Bald eagles can be seen annually along the Rock Falls' riverfront. Locations such as the Lower Dam Park, Sewards Park, the Jim Arduini Boat Ramp and the Sinnissippi Dam Walkway are prime locations that many bird watchers park and view the eagles from their vehicles.
There are two subspecies of bald eagles. The "northern" bald eagle, Haliaeetus leucocephalus alascanus, is found north of 40 degrees north latitude across the entire continent. The largest numbers of northern bald eagles are in the Northwest, especially in Alaska. The "northern" bald eagle is slightly larger than the "southern" bald eagle.
Both male and female adult bald eagles have a blackish-brown back and breast; a white head, neck, and tail; yellow feet, legs and beak; and pale yellow eyes. Immature bald eagles have a mixture of brown and white feathers, with a black beak and brown eyes in younger birds; some immature bald eagles have more mottling than others. Adult plumage develops when a bald eagle become sexually mature; it takes five years for a bald eagle to attain solid white head and tail feathers. For the first five years they gradually change; the beak turns from black to yellow, the eyes from brown to pale yellow, body feathers from mottled to dark brown, and head and tail feathers from mottled to solid white. Some bald eagles have leucism, a genetic mutation that affects feather pigment. A leucistic bald eagle can have patches of white feathers on its body and wings; have overall faded or pale feathers; or have overall white feathers.
A female bald eagle's body length varies from 35 to 37 inches; with a wingspan of 79 to 90 inches. The smaller male bald eagle has a body length of 30 to 34 inches; with a wingspan ranging from 72 to 85 inches. An eagle's average weight is ten to fourteen pounds. Northern birds are significantly larger than their southern relatives. Eagles sit at the top of the food chain, making them more vulnerable to toxic chemicals in the environment, since each link in the food chain tends to concentrate chemicals from the lower link. A bald eagle's lifting power is about 4 pounds. They do not generally feed on chickens or other domestic livestock, but they will make use of available food sources. Bald eagles will take advantage of carrion (dead and decaying flesh). Because of its scavenger image, some people dislike the bald eagle. Other people do not care for powerful and aggressive birds. Still other people object merely on the grounds that it is a bird of prey, which kills other animals for food.
Bald Eagle Monitoring Etiquette
Disturbance is defined as any activity that changes an eagle’s behavior. Example-if an eagle stops preening to study YOU then YOU have disturbed the eagle. Disturbances fall on a spectrum from minor (example above) to major (flushing from nest). The impact of disturbance on nest success can also vary from minor to major, up to causing a nest to fail, and frequently disturbance can cause a cumulative effect, meaning that frequent minor disruptions can be as problematic as infrequent major disturbances.
Am I Bothering an Eagle?
If an eagle does not stop to check you out while you are approaching him, then you’re not bothering him. If he does stop what he’s doing and notices you, but resumes his activity after giving you a once over, you are also probably not bothering him and are safe to continue observing him. If, however, the bird does not resume his task or become more agitated, you should back away until the eagle become comfortable again. An eagle that is alarmed by your presence will progress from simply watching you to sitting up in an alert posture and may begin vocalizing. As the bird’s agitation increases, it might start shifting in the nest/on its perch, raising its wings, leaning forward and preparing to fly and otherwise look anxious until it finally flushes from the nest/perch.
Eagle Comfort Level
As humans we all have an imaginary bubble that is the comfortable distance that we remain from others. Eagles are the same. What is the Eagle’s bubble? Anywhere from 100 feet to 1000 feet. Every eagle is different which is why you, as a lover of nature and our national symbol must be observant of his behavior. Nest stage seems to affect how eagles respond to human activity. The United State Fish & Wildlife Service recommends that active nest/feeding sites not be approached beyond a distance of 330 feet. Be observant. Eagles seem to have a lower threshold for disturbance during courtship, pair formation and nest building. Would you like strangers watching you intently while you did the same? Not likely. If you make the eagles uncomfortable, they may give up their site and move elsewhere.
We are blessed to have eagles feed and nest on the Rock River in very observable areas. There are many vantage points that can be utilized that will not disturb the eagles. Here are a few:
- Lower Dam Park look across the river on the island
- Bowman Park look across the river on the island
- Seward Riverside Park look up!
- Upper Dam Area (near the walkway)
- Sinnissippi Dam Walkway look toward Seward Park or above you-they may be circling
- 1st Avenue Bridge/IL Route 40
Rock Falls, IL: Where City Life & Nature Meet.