Bald eagle aeries are the grandest nests in Colorado
Curious Nature
Adobe Stock Image/Licensed by Walking Mountains Science Center
The bald eagle population has rebounded significantly since the 1970s and 1980s, and if you pay attention, you may spot quite a few this spring. As fortune would have it, our state sits in the annual migration path for many of these iconic birds, welcoming around a thousand raptors annually.
For roughly 200 breeding pairs, Colorado isn’t just a pit stop — it’s home sweet home. As we find ourselves in the middle of bald eagle nesting season, it’s time to spread our wings and dive into the fascinating world of these magnificent creatures and the awe-inspiring nests they call home.
Bald eagle nests, or aeries, are not your average twiggy abodes. They’re the mansions of bird nests, with the largest reaching up to 10 feet in diameter and 20 feet tall. The heaviest recorded nest weighed a whopping 4,000 pounds — similar to a small car. Most nests range from about 4 to 5 feet in diameter and 3 to 4 feet in height, which is still quite impressive. Constructed primarily from sticks woven together and filled with materials like grass and moss, these nests are often situated near lakes and rivers, close enough for mom and dad to catch fish.
Bald eagle nests typically start small and are expanded and refurbished each year. Bald eagles are all about commitment to their mate and territory, as they mate for life and couples typically return to the same nesting site each year. Their lifespan is normally 15-25 years in the wild. This means that if an eagle starts nesting at age 5, and lays two eggs a year, she could bring 40 new bald eagles into the world in her lifetime.
During nesting season, the pair will court, lay eggs, and nurture their offspring until they are ready to leave the territory. The first egg usually pops out about five days after the lovebirds get cozy, with the potential of two more eggs following suit.
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Once the eggs hatch, it’s all wings on deck as the parents take turns keeping the chicks warm and well-fed. And let’s not forget about the chicks themselves — after about 12 weeks, they’re ready to spread their wings and take their first practice flights. At some stage between 17 and 23 weeks, fledglings are prepared to leave the nesting territory for good. The entire nesting season process typically takes about six months to complete.
While it may be tempting to check out these remarkable nests and adorable eaglets up close, please do not. Human presence is extremely stressful to bald eagles at nest sites. It may cause nest abandonment, prolonged absences from offspring, and even cause fledglings to attempt to fly before they are ready. Observers must maintain a respectful distance from nesting sites, minimizing disturbances and allowing the eagles to fulfill their parenting duties without undue stress.
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Fortunately, there are plenty of opportunities for bird enthusiasts to observe bald eagles safely and responsibly, whether by admiring nest watch cameras online, using binoculars to view soaring birds at a distance, or participating in organized bird watch programs. There are even community science initiatives such as the Bald Eagle Watch Program where members of the public can train to monitor bald eagle nests across Colorado, helping provide valuable data about bald eagle nesting success.
Whether you’re a seasoned birder or just looking for a fun outdoor adventure, there’s something truly special about witnessing these magnificent creatures in action. Sharing our planet with bald eagles is a privilege, and it’s up to us to keep it that way.
