Raptors Rebound as Cell Towers Become Modern Nesting Sites

How Raptors Are Adapting to Urban Landscapes

Ospreys are migratory, spending the breeding season (spring through early fall) in Illinois before heading south to the Gulf Coast and South America. Juveniles do not return the following spring, but remain on wintering grounds until they are nearly 2 years old.

Unfortunately, the osprey has faced troubling times in the recent past. Thirty to 40 years ago, it nearly went extinct in North America due to dichloro-diphenyl-trichloroethane (DDT), an insecticide introduced in the early 1940s. Although DDT didn’t kill the birds outright, it caused a major problem with osprey eggs by thinning their shells, making them fragile and easily broken during incubation. After DDT was banned in the early 1970s, the osprey, along with other affected species, began to make a comeback.

Initially the recovery of the osprey was partially managed by installing elevated wooden platforms on tall poles, designed to resemble the open-topped trees where ospreys once built their nests. Out east, along the Atlantic shoreline, this approach was very successful and continues today.

Here in the Midwest, a similar approach has been used: Ospreys are raised in a somewhat controlled environment and then transferred to another area to breed once they become adults. It’s well known that fledglings—meaning they are capable of being on their own—mostly return to their natal area, especially the males, thus enabling the species to propagate further. This method is known as hacking.

Although hacking has produced a significant increase in the osprey population here in Illinois, something else has been happening at the same time. That something else is the use of other manmade structures such as lighting fixtures, power line structures and most recently, cell phone towers.

Photo credit Vic Berardi

 In 2020, only a few osprey nests were known to be on cell towers in Lake County. By 2025, at least 26 active nests have been confirmed in Lake and McHenry counties, with new ones being discovered regularly. The best time to see them during the breeding season is after the eggs have hatched and the nestlings begin to grow—just before they fledge, or leave the nest on their own. This usually occurs from late July through August. Both parents can often be seen busily feeding their young throughout the day.

Many of nature’s creatures, including the osprey, are becoming increasingly dependent on human-altered environments. The upside is that we get to witness their lives up close. The downside is that we bear greater responsibility to protect and sustain the habitats they now rely on.

Vic Berardi is the founder of the Illinois Beach State Park Hawkwatch and is a current board member of the Hawk Migration Association. He is an avid enthusiast who is recognized in the raptor community for his writings and outstanding photography. To connect with him, email [email protected].