Identification

Perching: Adults always have white heads and white tails. Immatures (less than five years old) have dark heads with very long beaks and mottled white on breast or under wings.

Flying: Long straight wings with exceptionally long "fingers" (outer primaries). Slow, fluid wing beats. Uniformly dark or mottled dark-and-white underwings.

Nesting Habitat

Large, mature cottonwoods or pines, usually in riparian areas along rivers or around large lakes or reservoirs. Most nest sites are well removed from human activity areas. Large stick nest is placed near the top of the tree. Inexperienced breeding pairs often build "winter nests" (unused for breeding) on wintering grounds prior to heading north to summer breeding areas.

Nesting Dates

Courtship: January to March Incubation: late February to late May Dependent nestlings: late April to July

Incubation period is 34-38 days. Young fledge 70-84 days after hatching and remain dependent on adults for several months after fledging.

Statewide Distribution and Population

More than 140 pairs currently nest in Colorado, up from fewer than 10 pairs in 1960. Highest nesting densities occur along the Yampa River, in the San Juan River basin, and in the South Platte River valley.

State and Federal Status

Federal – Delisted/protected under Bald and Golden Eagle Protection Act; state species of concern; Colorado State Wildlife Action Plan Tier 2 species.

Search and Nest Monitoring Protocol

Beginning in January, check historic and potential nest sites for activity. Visit nest sites every two weeks for 2-3 hours, supplementing on weekends to monitor nests for disturbance. Observation points should be at least 800 m from active nests and perches/roosts.

Recommended Nest Buffer Area

CPW recommends a year-round closure to surface occupancy (beyond that which historically occurred in the area) within 400 m radius of nest and no human encroachment from 15 November through 31 July within 800 m of the nest.

References

Bent, A. C. 1937. Life histories of North American birds of prey, part 1. U.S. National Museum Bulletin 167, Washington, D.C.

Johnsgard, P. A. 1990. Hawks, eagles, and falcons of North America. Smithsonian Institution press, Washington, D.C.

Kingery, H. E., ed. 1998. Colorado breeding bird atlas. Colorado Bird Atlas Partnership, Denver.

Snow, C. 1973. Bald eagle. Habitat management series for unique or endangered species. U.S. Department of the Interior Bureau of Land Management Technical Note 171.

Stalmaster, K. 1987. The bald eagle. Universe Books, New York.

Wickersham, L.E. 2016. The Second Colorado Breeding Bird Atlas. Colorado Bird Atlas Partnership, Denver.