Golden Eagle Migration in PA

If you hawk watched anywhere in Pennsylvania this week, you likely saw an impressive number of Golden Eagles. On Monday, two days after our first big winter storm of the season, the state saw its first large push of Golden Eagles.  At the Allegheny Front hawk watch in Bedford County, the record of 51 Golden Eagles in one day was broken and upped to 61; many smaller sites will be lucky to see that many in one season!

Here is a look at how the Golden Eagle flight played out this week at a few sites in Pennsylvania.

 
10/30
10/31
11/1
11/2
11/3
11/4
11/5
11/6
TOTAL
Allegheny Front32561177286129
Hawk Mountain21822142141
Second Mountain16920522036
Tuscarora Summit--111172----22
Jack's Mountain11003--01116
Stone Mountain0--1004117

(all data from HawkCount.org)

You didn’t have to be at a major hawk watching site to see a lot of Golden Eagles this week.  I broke my own personal record for number of Golden Eagles counted in one day, and I observed 3 Golden Eagles actively hunting in migration. If you think it’s impressive to watch a Red-tailed Hawk kite along a ridge, imagine a massive Golden Eagle doing the same, barely moving along a tree line as it scans the fields below. One of the eagles I observed came into view out of the corner of my eye in a steep dive into the treeline; I didn’t see what it was going after, but I imagine it didn’t stand a chance.

Red-tailed Hawks were still seen in decent numbers this week, and they seemed pretty upset at all the Golden Eagle activity. On one occasion, two large, dark eagles came into view and soared right above me.  Adult Golden Eagles typically migrate in pairs, and from my experiences, Golden Eagles of all age groups tend to come in “pairs.”  However, I soon noticed that one of the two eagles was not an adult Golden Eagle, but a juvenile Bald Eagle. I’ve seen juvenile Bald Eagles do some pretty goofy things during fall migration. It’s as if they don’t quite get it, and they either take a few extra minutes to figure out the best flight path, or they try to join up with other raptors that are already on a good path (and they are usually not welcomed by whatever they choose to follow). Despite the adult Golden Eagle’s attacks on the juvenile Bald Eagle, the juvenile Bald Eagle continued with it on the thermal, and then into a glide. Within seconds another Golden Eagle followed.

As the week went on, numbers of Golden Eagle decreased. This was likely the “peak” week for Golden Eagle migration this season in PA.

Total Number of Golden Eagles in Pennsylvania (all years, from www.ebird.org)

I never seem to get any great shots of Golden Eagles. I’m usually torn between observing raptors with my binoculars versus snapping photos, and in the end I usually choose my binoculars since I am currently hawk watching alone, and the eagles are usually at that distance where a photograph just wouldn’t come out very well.  So this week, I’ve asked some of my favorite raptor photographers to contribute photos of Golden Eagles. On each photo below, note that either Jerry Jordan, Vic Berardi, Alex Lamoreaux, or Jerry Liguori took the photo, and I thank all of them for contributing their amazing shots of an extremely difficult raptor to photograph.

Aging Golden Eagles in migration can be tricky if you aren’t at a site where you are either looking down on them or having them pass at eye level, and hopefully soaring.  Golden Eagles show a slight dihedral, which is why they are sometimes mistaken as Turkey Vultures or Red-tailed Hawks (both of which are still migrating in decent numbers as Golden Eagles begin migrating through Pennsylvania). Bald Eagles are more flat winged, and are typically mistaken as Osprey.  Both Bald and Golden Eagles are slow soaring and steady gliding raptors, and can be mistaken for each other, but note the smaller head, dihedral, and “tapering” of the wings at the body of Golden Eagles.

Steady gliding is the typical flight style for migrant Golden Eagles in Pennsylvania, and they tend to stay tight to ridges.  In a glide overhead or at eye-level, it can be extremely difficult to age Golden Eagles; the white patches on flight feathers and tails of juveniles and subadults can be completely obstructed while gliding, especially in bad lighting.  If you can see the white patches of immature birds, it can still be challenging to age them to a specific year.

In general, if you can see the upper side of an immature bird, you can begin to age it (very generally). Juveniles are the only age class that does not show a tawny upper wingbar; the backs of juvenile are uniformly dark brown (This upper wingbar is the result of faded upperwing coverts of older immature and adult birds; do not mistake this for the “two-toned” appearance of immature Bald Eagles).  Juvenile and subadult Golden Eagles show varying amounts of white at the base of flight feathers and at the base of the tail. The amount of white on the upperwing in comparison to the underwings can vary on each individual.  Further, not all immature Goldens show white wing patches; some juveniles lack them completely.  So, if you happen to see a Golden Eagle with no wing patches, you don’t get a look at its upperside, and its tail is folded, you cannot say for sure that is immature or an adult (and bad lighting does not help the situation). On the other hand, if you get a glimpse of white in the base of the tail, you can say for sure that you are at least seeing an immature bird, and you can hope to catch a glimpse of the upperside to narrow it down to juvenile or subadult. It is possible to further age subadult Golden Eagles, but only if you get lucky enough to see a specific molt pattern and as always, taking photographs is a good idea if you really want to be sure of what you’ve seen.  The best guides for aging subadult Golden Eagles, in my opinion, are Jerry Liguori’s raptor ID books, “Hawks From Every Angle” and “Hawks at a Distance.”  (buy both here….and here!)Even then, don’t expect to age every Golden Eagle you see.

Golden Eagle - subadult (Photo by Vic Berardi)

Jerry Liguori further notes on the above photo that this is a subadult that has molted at least twice. “Its tail is made up of sub-adult feathers that have a narrow grayish band after the white base. The remiges have more than one age of sub-adult feathers (showing the darker trailing edge), as well as molt on the underbody.”

Golden Eagle - juvenile; Note uniform dark brown back and lack of tawny wing bar (Photo by Jerry Liguori)

 

Golden Eagle - subadult; Note white base of tail feathers and tawny upper wingbar (Photo by Alex Lamoreaux)

Captive immature Golden Eagle (educational bird) at Grandfather Mountain in Boone, NC (Photo by Jerry Jourdan)

Adult Golden Eagles are just about the most impressive looking raptor to see migrating. Even though they appear mostly dark, there are very subtle field marks that make them very striking.  Adult Golden Eagles are the only age class that does not have white in the tail.  Instead, they have pale gray bands in the tail that are noticeable only at close distance.  At a distance, the tail appears all dark, and the pale undertail coverts can sometimes appear white, like that of immature individuals.  Underwings of adults appear all dark (and two-toned, like that of a Turkey Vulture), but can show some white mottling from molt.  Adults show a tawny upperwing bar and a pale golden nape (like subadults).

Golden Eagle - adult; Note gray barring in tail and flight feathers (Photo by Jerry Liguori)

Golden Eagle - adult; Note lack of white in tail and in flight feathers (Photo by Jerry Liguori)

 

Thanks again to Jerry Jourdan, Vic Berardi, Jerry Liguori, and Alex Lamoreaux for contributing their excellent photos! Be sure to check out Jerry Liguori’s frequent posts on Utah Birders, and Jerry Jourdan’s Birding and Digiscoping Blog.