Golden Eagle (Aquila chrysaetos)
Measurements: 0.75-0.90m long; wingspan 1.90-2.27m
On the whole, people and Golden Eagles don’t mix very well. The bird is most numerous in places with a sparse human population, in habitats such as high mountains, cliffs, large forests and wetlands. And many people don’t like eagles; they accuse them of killing domestic animals or gamebirds, and persecute them as a result. So in much of Europe the Golden Eagle has been wiped out, displaced by its nemesis.
By USFWS Mountain-Prairie – Golden eagle on power pole at Seedskadee National Wildlife Refuge, Public Domain, https://commons.wikimedia.org/w/index.php?curid=69188186
It is certainly true that this magnificent raptor is a very effective hunter. It takes a wide range of live prey that certainly includes a few game birds, and there are reliable records of individuals attacking fawns of the Roe Deer (Capreolus capreolus), too. But in general, the Golden Eagle takes rather modest prey for a bird of its size and power. It prefers mammals such as rabbits and Mountain Hares (Lepus timidus) and birds such as grouse, crows, seabirds and ducks. It is very unusual to see one killing anything larger, and the numerous tales of sheep and lambs being harried are probably mostly fictional, or misinterpreted. That’s not to say that Golden Eagles don’t eat sheep or goats; they do. It’s just that they take them as carrion when they are already dead, just as we do.
The Golden Eagle uses its 2m wingspan to fly low and slowly over vast tracts of open countryside; it does not go in for hunting from a perch, or making showy dives from a great height. In common with most birds of prey it has very acute vision, and will easily spot the movement of a quarry within a range of 1000m or more as it quarters along and scans. Alternatively it might cause prey to stir by its very appearance; the sight of a low-flying Golden Eagle invites many a quarry to break cover and flee in panic. If so, the eagle can pick it off with a quick stoop.
Members of a pair sometimes hunt co-operatively, and there have been some remarkable observations of this in action. In its commonest form, one bird acts as the “beater”, flushing prey out by quartering low or even walking on the ground, whilst the other mops up. But there are also records of birds attacking deer fawns by separating them from their mothers, one bird distracting the adult, the other concentrating upon the youngster. It is not known how often such teamwork is actually used.
To work so well together, a pair needs to know each other, so it’s not surprising that Golden Eagles are both highly sedentary and faithful to their partners; they live a settled life. Most pairs live within a large home range that is between 50km² and 100km² in extent, and they never go outside it unless forced to by extreme weather. Over the years they get to know their area well, and find out the best places to hunt. Home ranges may pass down the generations.
By USFWS Mountain-Prairie – Golden Eagle on Seedskadee NWR, Public Domain, https://commons.wikimedia.org/w/index.php?curid=69193669
Within the home range is the nest-site, the eyrie, the only part of a Golden Eagle’s patch that is vigorously defended from intruders. In fact a pair will usually have several nest-sites (up to 11), which can be used as circumstances dictate, and they will sometimes refurbish more than one nest in a single season. Most are placed on a cliff ledge, but tall trees are also used, and may buckle under the strain of the structure being built up over many years. Golden Eagles nests have been recorded that were 5m tall and 3m wide.
In early spring between one and three eggs are laid, each at 3-4 day intervals. With incubation beginning with the first egg, the resulting chicks are of different ages and, where there are two birds, it is common for the younger one not to survive (80% of cases). This may be either because of inherent weakness, or because it is intimidated or killed by its older sibling.
Once fledged, though, young Golden Eagles are looked after and tolerated by the parents for a considerable length of time. They often leave the home range during the winter, or even hang on until the following spring.
From ‘Birds: A Complete Guide to All British and European Species’, by Dominic Couzens. Published by Collins and reproduced with permission.