Ageing Golden Eagles in Flight

by Jerry Liguori
(An article submitted to "Utah Birds" in November 2008)

Golden Eagles are large birds with extremely long, broad wings, which are held in a dihedral when soaring and slightly bowed when gliding. They appear slow moving in flight, and exhibit heavy, languid wing beats. Golden Eagles are dark with a golden nape (typically appearing all-dark at a distance) but immature (all ages except adult) birds have varying amounts of white in the wings and tail. Adult Golden Eagles are present along the Wasatch Mountains most times of the year, but during spring and fall migration Golden Eagles of all ages are seen with regularity.

In flight, many Golden Eagles are difficult or impossible to age without seeing the bird’s topside or the tail fully spread. However, it may be possible to see white in the wings or tail, or molt in the flight feathers (tail and wings) to narrow the age to non-juvenile or non-adult. This article is made to point out the difficulties in ageing 1-3 years old Golden Eagles in flight, since birds 1-3 years old with white in the wings or tail look similar in plumage to each other.


Juvenile (up to one year old), sub-adult I (1-2 years old), and sub-adult II (2-3 years old) Golden Eagles are often inseparable in the field without ideal, close-up views. All three ages have a white tail with a dark tip, and varying amounts of white along the base of the primaries gradually becoming uniformly dark as they reach full adult plumage, which takes from 4-6 years. The white in the tail is typically extensive, covering more than half the length of tail, but can be restricted to the base in rare cases (Figure 4, left / juvenile). Sub-adult I Golden Eagles (Figure 2) retain most of their juvenile feathers and appear nearly identical to juveniles (Figure 1) in the field. Also, the inner primaries, inner secondaries, and central tail feathers that are replaced on sub-adult I birds are impossible to distinguish.

Sub-adult II Golden Eagles (Figure 3) are comprised of mostly sub-adult feathers, with some retained juvenile feathers. On some sub-adult II birds, the central tail feathers may be replaced with adult feathers, causing the tail to look dark centered or ‘split’ (but this usually occurs on sub-adult III birds). Sub-adult II birds may replace all of their juvenile secondaries, but sometimes retain a few juvenile secondaries, which will project slightly beyond the rest of the wing. On sub-adult II birds, primary molt occurs towards the outer end of the wings, thus, a Golden Eagle with a white base to the tail that is molting outer primaries is almost certainly a sub-adult II bird. Birds that are not actively molting are difficult to age.


The upperwings of juveniles are uniformly brown, but the upperwing coverts and golden nape typically fade by spring and appear paler than usual (Figure 4, middle). Juveniles lack any signs of molt (replacement of feathers) during fall, with their wings looking even along the trailing edge; other ages often show wear along the edge of the wings. Juveniles are also the only age to lack pale, mottled upperwing ‘bar’. Golden Eagles with extensive white wing patches to the underside of the wings often show small white patches on the upperside of the primaries (Figure 1, right).

Some upperwing coverts on sub-adult I Golden Eagles are replaced, with the new pale feathers forming a narrow, mottled upperwing ‘bar’. The faded upperwings of juveniles in spring are broad and even-toned.

Be careful, certain traits on Golden Eagles can be misleading. In direct sunlight, the pale undertail coverts can be mistaken for the white tail base of immature birds. In spring when the head is faded, Golden Eagles may exhibit a pale-headed appearance that can look like the white head of a Bald Eagle (Figure 4, middle / juvenile). Also, the flight feathers (including the grayish tail bands) of adult Golden Eagles may appear whitish similar to immature birds when illuminated by snow cover (Figure 4, right).

Photos by Jerry Liguori


          Figure 1

          Figure 2

          Figure 3

          Figure 4

 Photos by Jerry Liguori


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