I have a project that is coming up that could impact a golden eagle (Aquila chrysaetos) nest. I wanted to put this note together to get all of the info I have together. The crux of this note will focus on what we know about eagle disturbance.
- CLASS: Aves
- ORDER: Accipitriformes
- FAMILY: Accipitridie
- GENUS: Aquila
- SPECIES: chrysaetos
- IUCN: Least Concern
- Colorado BLM: Sensitive
General Life History
Feeds on small prey most of the time and is more of a predator than a scavenger (like the bald eagle). It eats prey up to the size of a fox or a large crane (known to take goats or small deer as well). A pair may hunt together.
Utilizes a variety of open habitats: tundra, prairie, rangeland, or desert. Wide ranging in the winter. Is more restrictive in the summer to areas with good nesting habitat.
May mate for life.
Usually there are 2, sometimes 1-3, but rarely 4 young. Both male and female incubate. Female usually incubates more. Incubation lasts around 41-45 days.
The female stays with the young at first, while the male hunts. After the young start to loose their down, the female leaves the nest to help hunt.
Young first fly 60-70 days after hatching.
Nests are most often high and well protected on a cliff face. Also, may nest in large trees or, rarely, on the ground. Typically nests sites are used repeatedly for many years. Often, within a territory, there will be an alternate nest. Nests are constructed by both sexes with sticks and lined with weeds, grass, leaves, and moss. New material is added each year. Nests can become quite large.
- Research suggests that golden eagles are senstive to human activity. Steidle et. al. (1993) found when observers were camped 400m (1300 ft or 1/4 mile) for 24 hours from golden eagle nests, adults spent less time near their nests, fed juveniles less frequently, and fed themselves and their juveniles up to 67% less food than when observers were camped 800m (2600 ft or 1/2 mile) away from nests for an equal period of time.
- In Idaho, in a study of 40 years of golden eagle territories, data showed that areas that experienced OHV use (>4 km/km2 within 3 km of the nest) saw a substantial decrease in nest productivity when compared with nests that had less OHV activity (<3km/ km2 within 3km of the nest). Nests that were near parking lots (<700m) were particularly affected - some not producing young for up to 15 years (Steenhof et al. 2014). *Interestingly, it appears that helicopters may not have an impact on Golden Eagle reproduction (Grubb et al. 2010).
Timing limitations and spacial buffers are commonly used to protect golden eagle nests during the breeding season. Typically a 1/2 mile no disturbance buffer is recommended from at least February 1 - July 15. Some recommendations differ (for example: Colorado Parks and Wildlife recommends timing limitation from December 1 - July 15). Others recommend no activity period within 1/2 mile of the nest, without consideration to the time of year (this option can be better because it eliminates the need for area closures during the breeding season which can be time intensive).
References with no Link
Steidl, R. J., K. D. Kozie, G. J. Dodge, T. Pehovski and E. R. Hogan. 1993. Effects of human activity on breeding behavior of golden eagles in Wrangell-St. Elias National Park and Preserve; a preliminary assessment. National Park Service, Wrangell-St. Elias National Park and Preserve, Copper Center, Alaska, WRST Research and Resource Report; no. 93-3.