Written by: Camille Ledoux (March 2024)

The bald eagle has been the national emblem of the United States since June 20, 1782. Nature At The Confluence has been lucky enough to be a cherished habitat for a nice pair of bald eagles. Before catching up on our resident pair, which we have named Sobo and Tebo, let’s dig into the story of their species. 

Bald eagles are native to Northern America. They tend to stay close to large bodies of water and associated grasslands, marshes, rivers, and streams, which makes The Confluence the perfect habitat for them. The eagles reuse their nests every year, so they can become pretty big, up to 13 feet (4 meters) tall and 10 feet (3 meters) across. This photo taken by James McDowall shows our eagles’ nest. 

Bald eagles are opportunistic foragers but prefer fish as their primary, so they are often found where fish are abundant. They also eat sea birds and ducks or hunt over grasslands and marshes for small mammals such as rabbits, squirrels, prairie dogs, and muskrats.

In the mid-1900s, bald eagles were in danger of extinction. Bald eagles were decimated by habitat destruction and degradation, as well as illegal shooting and the contamination of their food source by the insecticide dichlorodiphenyltrichloroethane, known as DDT. In 1940, Congress passed the Bald Eagle Protection Act, which prohibited killing, selling, or possessing the species. In 1972, as the dangers of DDT became known – in large part due to Rachel Carson’s book Silent Spring – the Environmental Protection Agency banned the use of DDT and some related pesticides in the United States. Bald eagle populations throughout the country have continued to rise after these actions were taken, with an estimated population of 72,434 individual eagles in 2009. Estimates for the bald eagle population, based on data from 2018 to 2019, total 316,700 individual eagles. This research shows that protecting the environment is vital in order to keep our native animal species. Photo of eagle adding nest material taken by Kurt Van Galder on February 13, 2024.

Before the Nature At The Confluence campus was completed in 2017, eagles nested in a tree located on an island within the Rock River, just south of the Shirland Avenue bridge. In 2022, the dead tree holding the eagle’s nest came down in a winter storm. The pair wasted no time building a new nest on the other side of the island, visible only before the tree leaves returned. In the spring of 2023, the eagles began a new nest at nearly the same site as the first one, visible perfectly from the “Eagle Point” section of our trail.

The nesting season started in October, and thanks to multiple local photographers, we have received many pictures of our resident pair, Sobo and Tebo, in action. Our two residents will stay together for up to 50 years, since they mate for life. Eagle nestling photo captured by Kurt Van Galder on March 2, 2024.

Our eagles did not lay an egg in 2023, nor spring 2024. It’s not because they haven’t tried, as visitors have witnessed them mating. There could be a genetic reason behind this, just as some animals and humans are unable to reproduce. Other possible reasons for their lack of egg-laying might be changing climate and weather patterns, ingested pollutants, or  because they are too old. The eagles won’t necessarily remate, but it is normal for some species to have more than one mate. Usually the “trio” would be two females for one male.