The state of Colorado has launched a new four-year study to investigate why bald eagle populations are thriving along the state’s Front Range.
Scientists are specifically focusing on why human populations, which have grown in tandem with the eagles, haven’t interfered with their comeback.
Bald eagles, a symbol of national freedom, were decimated in the mid-20th century. Conservation efforts, along with banning the pesticide DDT in 1972, have allowed populations across North America to rebound in a big way.
But birds returning to their native habitats in Colorado are “finding landscapes that are remarkably different,” said Garth Spellman, an ornithologist (someone who studies birds) at the Denver Museum of Nature and Science. “It sets up an interesting question: How do these wild animals interact with these modified environments?”
Riparian areas, or the habitats along bodies of water, are the most common nesting sites for the birds, so Spellman speculates that human-built reservoirs may serve as new and attractive homes for the raptors. Still, most human activity seems inherently disruptive to animal habitats. Building more roads, trails, boating areas and cell towers aren’t often the key to balanced ecosystems.
“The assumption has been, for a long time, that bald eagles are very sensitive to changes in their habitat,” Matt Smith, an ecologist with the Bird Conservancy of the Rockies, said. “So to see bald eagles being successful in developed areas — it runs a bit counter to the conventional wisdom for that species.”
As human populations grow along the Front Range, bald eagles seem to be keeping up
According to Colorado Parks and Wildlife, in the decade between 2019 and 2029, another 832,000 people are expected to move to the state, with the vast majority taking up residence in the Front Range. Bald eagle populations have kept up, too: 90 breeding pairs live in this same corridor, up from zero in the 1970s.
The study will involve scientists and volunteers from Colorado Parks and Wildlife, the U.S. Fish and Wildlife Service and the Bird Conservancy of the Rockies, among others. Around 25-30 birds will be outfitted with light-weight trackers that ping from nearby cell towers. An army of volunteers and officials from the city to the federal level will help collect a data on things like nesting sites, too.
It’ll be the most comprehensive study on bald eagles ever conducted in the state.
The bald eagle population growth can also be felt right here in Denver. According to a public bird-sighting database from the Cornell Lab of Ornithology, at least two bald eagles were spotted in the city in July. And our own reporting shows City Park and Washington Park are the top hot spots.
Bald eagles’ success may provide a key to helping other species, like golden eagles, which haven’t shown the same kind of resilience as their bald counterparts.
“Across North America, we’ve lost billions of birds in the last 50 years,” Spellman said. “It teaches us a lesson about how conservation can be successful and how we can help other species at risk. And that really is, to me, one of the greatest results that could come from the study.”