Forty years ago, the sight of a bald eagle in the Fox Valley was quite rare. Birding groups that track the presence of bird species in the winter months might find one eagle across the tri-county area of Kane, Dupage and Cook County. The sight of a bald eagle during Christmas Bird Counts was a cause for celebration indeed.
How things have changed.
In 2018, there are dozens of bald eagles to be found along the Illinois stretch of the Fox River from the Chain-O-Lakes region south to Yorkville and beyond. The species now breeds in multiple locations with massive nests built of large sticks perched in tall trees.
These nests typically produce 1-2 young per year if weather or calamity do not combine to kill the young birds as they fledge. A few years back a pair of eagles breeding on the Mooseheart property nearly lost their young when their next blew out of a pine tree on the western edge of the campus. These birds were snatched up by wildlife rehabilitators and released once they achieved a level of maturity sufficiently large and strong to hunt on their own.
That pair of eagles moved their next operations eastward, and now maintain a next next to the Moosheart stadium along Mooseheart Road. These birds seems to have few qualms about the attention they attract. Their next is in plain view of thousands of passing cars. Police and Moosheart property managers have to shoo away cars parked along the roadway where people sometimes stop to shoot photos of the two parents and fledgling young.
Experts once thought eagles and their nests needed strict protection and privacy or the birds would not breed successfully. This is quite obviously not true. The Mooseheart eagles ignore the fact that their nest at the top of a dead pine tree is easily approachable by human beings. Their young somehow manage to flap and wing their way to safety once the nesting stage is over, and the eagles are perching there now in anticipation of the coming breeding season.
This brand of eagle success is happening all up and down the Fox River. Bald eagles at various stages of maturity are seen along the Fox River daily. It takes four years for bald eagles to go from dark fledgling to adult maturity with fully white head and tail. First-year eagles are dark from beak to tail, with mere echoes of white in the tail. Second year birds develop white mottling across the front of the breast, giving them the moniker “white bellies.” In the third year, bald eagle plumage starts to show more white in the head and neck. A Dark eyestripe defines this stage of development with a less defined white band across the belly and a patch of white on the upper back.
Life as an adult eagle
Finally, in the fourth year of life, bald eagles of both sexes develop a fully white head and tail. Some may still show flecks of brown feathers in the head and even white speckling in the body or back feathers. Eventually the birds clear up their plumage to achieve the strikingly bold white head and tail of adults. That’s when they are prepared to breed.
So nature requires quite a bit of survival capabilities for eagles to reach breeding stage. This breeding fitness means the birds have learned to hunt, avoid calamity and survive through all kinds of weather and seasonal changes. This is how the process of evolution works to test and refine breeding fitness.
When they reach adult status, eagles seek a mating bond that may last for years. The rituals of mating eagles are absolutely breathtaking to see. The adult birds soar high in the air, then clasp feet and hurtle down in spinning fashion, wings flailing as they tumble through the air. The spectacle makes one fear for the birds, but this is yet another test of fitness between the adults.
None of this was commonly seen in the Fox Valley for decades. There were many factors that affected bald eagle populations. Primary among these threats was the known fact of chemical pesticide poisoning that accumulated in the bodies of adult eagles at the top of the food chain. This resulted in weakened eggshells that were so thin from the stress on the bird’s bodies they would break during the brooding process. All birds move and nurture their eggs during nesting. Eagles often must perch and brood through violent storms and keen weather extremes. If an egg is fragile from any cause it will not produce a young eagle.
The streams and rivers upon which eagles depend for fish and food were also deeply compromised up to forty years ago. Chemical pollutants including agricultural, municipal and industrial runoff were allowed to sully rivers such as the Fox. In the early 1970s, efforts to change this pattern were introduced in legislation passed with bipartisan support in Congress and signed by the president. Republican President Richard M. Nixon also signed into being the Environmental Protection Agency (EPA) the government agency responsible for enforcing environmental laws.
Without these initiatives, it is certain bald eagles would not have made a comeback in the Lower 48 of the United States. Eagles still survived in the wilds of Alaska and across Canada, but even in Florida where eagle populations are now healthy, the birds were disappearing by the year due to the impact of pesticides such as DDT in their bloodstreams.
Now that eagle populations have increased, the birds are becoming a familiar site even to casual observers.
Their hunts for fish along the Fox River between the Wilson Street Bridge and the Challenge Dam have attracted many onlookers. Some come equipped with binoculars, scopes or cameras. Others just come to gaze up at the birds with seven-foot wingspans.
On clear days the white head and tails of the adults can be seen above the river all the way from Route 31. The birds wheel over the Depot Pond and dive to catch fish with such efficiency people marvel the birds don’t get fat from all their success.
The gulls that gather along the river are sometimes the beneficiary of fish lost by the eagles. Come spring, the bald eagles will likely be joined by a species of birds known as osprey (Photo above) Those birds breed at Fermilab, and were once as threatened as a species as the bald eagle.
The health of the Fox River is generally far better than it was forty years ago, when fish including bass exhibited lesions from the impact of pollutants on their bodies. Unhealthy fish led to unhealthy birds among species that depend on fish for food. These include water birds such as great blue herons, common egrets, black-crowned night herons, double-crested cormorants, common mergansers, hooded mergansers and other fish-eating species now seen with frequency on the Fox River.
But the peak of the food chain are the great predators such as bald eagles. Batavia is now the beneficiary of legislation passed dozens of years ago to protect bird species and improve the environment. Those challenges are never finished, as even today there are issues with phosphates flowing into the Fox from agriculture sources and water treatment plants. No one knows the net effects of these changes over time, so monitoring is critical and groups such as Friends of the Fox River and the Batavia Environmental Commission collaborate for river cleanups and tracking activities. These Citizen Science efforts provide valuable feedback to local, regional and national authorities.
In that respect, the significance of the bald eagle as our national symbol has taken on new meaning with time. It is a symbol that represents pride in place as well as pride in process. The soaring sight of an eagle in flight should be inspiring. In some ways it captures the best of what human beings are all about.