Unlike other birds which are generally small, golden eagles are very large and powerful in comparison to other bird.  In the Snake River canyon in Idaho, nests are 5 to 8 km (3.1 to 5.0 mi) apart, while two other nearby studies in Idaho found the average distance were 4.3 km (2.7 mi) and 4.39 km (2.73 mi), respectively.  In a study of 170 eyries in the state of Wyoming, 111 were on deciduous trees, 36 in ponderosa pines (Pinus ponderosa) and 23 on sides of buttes or bluffs along river.  In Armenia, the average egg measured 76.5 by 59.1 mm (3.01 by 2.33 in) and weighed 123 g (4.3 oz). (1996).  6 (40%) of 15 nestling losses in nests in Central Europe were from cainism.  At night, the female generally appears to do all of the incubating.  In Scotland, there may be a weak link between food supply and cainism.  A mean of 48 clutches from Algeria and Tunisia showed an average of 1.89 eggs per nests, with a range of 1 to 3.  In Israel, at 60–70 days old after fledging, the juveniles were still close to nest and quite dependent on parents for food.  In Idaho, there was an average of 6 nests per pair. If it is not directly killed, the younger sibling may starve to death, which may be an even more common occurrence. The average weight is 5 oz. A breeding pair is formed in a courtship display.  A radio-tagged juvenile in Spain travelled a range of more than 16,000 km2 (6,200 sq mi) in its first three years of independence, then ultimately settled in a vacant territory 26 km (16 mi) from its hatching place.  In Wyoming, the tree nests are often the tallest tree in a stand and are in a small or isolated woodlot less than 500 m (1,600 ft) away from large clearcuts or fields. Eggs of golden eagles in California weighed from 113.9 to 176.6 g (4.02 to 6.23 oz), averaging 141.4 g (4.99 oz).  In the U.S., egg laying can be from anywhere between January and September, though is usually in March or later. This height preference may be related to having the ability to transport heavy prey downhill rather than uphill. The initial flight often includes a short flight on unsteady wings followed by an uncontrolled landing.  In each case, the natural predators of these animals are just the right size for golden eagle prey, and therefore avoid active eyries.  The average amount of food brought to the nest daily was notably higher in Idaho and Montana, where an average of 1,417 g (3.124 lb) and 1,470 g (3.24 lb) of prey were brought to the nest, respectively, than in Texas, where an average of 885 g (1.951 lb) was brought. All Rights Reserved. The American Eagle Foundation is proud to partner with: Copyright 2020 American Eagle Foundation. Diving from great heights, they have been clocked at close to 200 miles per hour.  After viral hemorrhagic pneumonia (VHP) killed off many rabbits in Spain, the average breeding success of golden eagles in Northern Spain dropped from 0.77 in 1982–1989 to 0.38 by 1990–1992.  In Switzerland, juvenile birds traveled an accumulated range of 2,000 to 15,000 km2 (770 to 5,790 sq mi) whereas the adults never left their home ranges of 75 to 191 km2 (29 to 74 sq mi).  Once they attempt to nest for the first time, golden eagles will often return to the vicinity of the natal zone, regularly within 7 to 65 km (4.3 to 40.4 mi) of their original nest site, sometimes attacking and even killing older golden eagles pairs if they occupy the area. Juveniles disperse widely during their first year, with males remaining closer to the natal area than the more highly exploratory females. "Causes of low productivity in the Golden Eagle. These may simply reflect a relatively unstable period of population adjustment. The American Eagle Foundation (AEF) is a 501(c)(3) non-profit organization. Golden eagles usually mate for life.  The movements of first-year eagles from Denali National Park averaged more than 5,500 km (3,400 mi), with surviving individuals migrating south to western Canada and the Western U.S. in autumn then moving back north to western Yukon and Alaska in spring. "Abundance and distribution of nesting Golden Eagles in Hudson Bay, Quebec", "Results of a helicopter survey of cliff nesting raptors in a deep canyon in southern Idaho", "Breeding biology of the golden eagle in southwestern Idaho", "The trend of Golden Eagle territory occupancy in the vicinity of the Altamont Pass Wind Resource Area: 2005 survey", "A Population Study of Golden Eagles in the Altamont Pass Wind Resource Area: Population Trend Analysis 1994–1997", "Nest site characteristics of a predominantly tree-nesting population of Golden Eagles", "Birds of the Kilbuck and Ahklun Mountain Region, Alaska", "Nest use, interspecific relationships and competition for nests in the Bearded Vulture, "Mating behaviour in the Golden Eagle in non-fertilization context", "Notes on the growth and behavior of young Golden Eagles", "Post-fledging movements of Golden Eagles, "Dispersal and migration of southwestern Idaho raptors", "The First Case of Successful Breeding of a Golden Eagle, "Golden Eagles successfully breeding in subadult plumage", "Nesting of subadult Golden Eagles in southwestern Idaho", "Breeding responses of raptors to jackrabbit density in the eastern Great Basin Desert of Utah", "Dietary response of three raptor species to changing prey densities in a natural environment", "The long-term effect of precipitation on the breeding success of Golden Eagles in the Judean and Negev Deserts, Israel", "Territory size, activity budget, and role of undulating flight in nesting Golden Eagles", https://en.wikipedia.org/w/index.php?title=Reproduction_and_life_cycle_of_the_golden_eagle&oldid=975634458, Creative Commons Attribution-ShareAlike License, This page was last edited on 29 August 2020, at 16:20.  Females do a majority of, but not all, of the incubating and largely attain their own food up to the stage of egg-laying, after which they are typically fed by the male.  As the eagles use a nest repeatedly, they repair their nests whenever necessary and enlarge them during each use.  Cliff nests are preferred as nesting sites in most of North America.  Greek nests are mostly on cliff ledges, but in the Evros District, nearly 30% of the population nests on trees, mostly pines.  In the Spanish Pyrenees, however, nest were found at up to 1,500 m (4,900 ft) in elevation.  In Belarus, the average brood size is reportedly 1.8 whereas the average number of fledglings is 1.1. It is apparently common for the younger, weaker siblings to stop begging for food after sibling aggression starts and the parent eagles do not feed the nestlings unless they beg.  In Spain, studies revealed the preferred sites of golden eagle nests were on inaccessible cliffs at a great distance from tracks, roads and villages.  80% of nests in Spain are on rocky cliffs, the remaining 20% being in trees.  In Washington state, tree nests averaged 90 cm (35 in) in depth and 1.2 to 1.5 m (3.9 to 4.9 ft) in diameter. Hunt, W. G., Jackman, R.E.  After the young are about 20 days old, the amount of aggression between siblings (if both survive) decreases and both chicks can usually fledge, though aggression may again increase shortly before fledging.  In the Kilbuck and Ahklun Mountains area, three pairs had eggs hatched from May 14 to 23, and young fledged from July 8 to August 10 with a median date of July 23 for 11 nests. Rainy years in the deserts of Israel, which provide more brown hares and chukars to hunt, were more successful years for breeding. & Reid, R. (2009). Cliff nests are 1-1.5m across and up to 2m high, while tree nests can be twice this size.  In Ethiopia, the estimated range of egg-laying dates ranged from October 24 to January 5. The average food consumption of the nestling sexes averages 691 g (24.4 oz) and 381 g (13.4 oz) per day, respectively, with male nestlings weighing about 500 to 600 g (1.1 to 1.3 lb) less than the equivalent-aged females. The largest mean clutch size across the range was 2.1 in Montana. The traditionally classified genus can be broken down into two groups: facultative cainists (wherein fewer than 90% of known nests do the oldest nestling attack and kill their younger siblings) and obligate cainists (wherein more than 90% of nests do the older kill the younger siblings).  Fledging occurs at 66 to 75 days of age in Idaho and 70 to 81 days in Scotland.  Sometimes called “biologically wasteful”, this strategy is most commonly explained as useful for the species because it makes the parents' workload manageable even when food is scarce, while providing a reserve chick in case the first-born dies soon after hatching.
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