A year in the life of an eagle

Adult, paired Golden Eagles normally stay together with their partner throughout the year. They also usually maintain a single territory and this is true also in the Alps. The birds do not leave their territories during the winter. Each Golden Eagle territory usually contains a number of nesting sites (average 5-6), any of wich may be selected for use according to the immediate needs of the birds. In February the eagles undertake intensive repair work on their nests. Both partners are active in building a new nest or repairing an old one. It is exactly at this time that the birds decide which nest will be used within the territory.

In late winter one can often watch the eagles perform their display flights aimed at other neighbouring eagles. Later in the breeding season these displays are not so frequent but they may still be seen, particularly in areas where there are high densities of eagles.

Shortly before egg laying, which in the Alps is usually between the end of March and the beginning of April the eagles begin to bring green branches to their nests. This behaviour is common amongst many birds of prey and has perhaps something to do with defensive mechanisms against parasites. It is also observable, but not so regularly, throughout the breeding season.

The egg clutch of the Golden Eagle is usually two eggs. The incubation of the eggs is mainly undertaken by the females although the males also do some of this work so that the females may hunt. During this time the main job of the male is to keep intruders, including other Golden Eagles, away from the nesting site and the territory.

The incubation time for the eggs is between 43 and 45 days. In the Alps hatching usually occurs at the end of April. Because incubation starts immediately after the laying of the first egg, the hatching of the young is asynchronous.

The freshly hatched eagle chicks are looked after almost continuously for the first 14 days by their parents. The food for the young birds is captured by both parents and brought to the nest. Until they are about 30 days old the young are fed small morsels of prey, already cut up and ready to eat. Later they become capable of portioning and eating their own food. Visits of the parents to the nest become shorter and are limited to delivery of whole prey items.

The nestling time takes a total of between 65 and 70 days. Usually the weaker (normally the second hatched) chick is killed by continuous aggressive confrontations between the chicks so that only one young bird survives to fly out of the nest.

In the Alps the young birds leave the nest usually during the second half of July. After their first flights the young stay within the immediate vicinity of the nest. They remain within the parental territory of their parents until the following winter and only leave when they are forced to by the parents at the beginning of the next breeding season. At this time they will venture far afield and only return to the area of their home territory when they are about 3 years old. Golden Eagles usually become sexually mature at the age of 4 to 5 years. Occasionally individuals will exhibit nesting bahaviour in their second year and are ready to pair in their third year. Golden Eagles are very long lived birds and can reach a healthy old age of 35 or more.

 

Overview graphics of a year in the life of a Golden Eagle




Golden Eagle chicks are white to pale grey from the time of hatching until they reach 20-25 days old.
(Foto: © NPS K.Bliem).




Shortly before they fly out from the nest, young Golden Eagles, with their wings folded, are hardly distinguishable from their parents.
(Foto: © NPS, K. Bliem).



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