Age classes in bald eagles

We hadn't necessarily intended this, but in our forty-five minute shoot at Hershey we got enough pictures for a brief primer on ageing bald eagles. It's not an exact science—there's quite a bit of variation, especially in sub-adults, and some individuals achieve full adult plumage more quickly than others, but we can at least outline the typical progression. 

Juvenile (first-year) birds are dark overall, especially when they fledge, but the juvenal plumage seems especially prone to fading and by this point in the year some birds will be quite tawny. The eyes are brown and the beak anywhere from black to grey.

Subjectively, first-year birds sometimes present a somewhat disheveled, loose-feathered appearance—Jessa compared this one to a Muppet. That impression probably isn't helped by their often undignified behaviour. Juvenile baldies, naturally enough I suppose, seem far less...together than their older counterparts. 

The juvie is obvious in this shot, yes?

Second-year birds (sub-adult I plumage) are known to hawk-watchers as "white-bellies", though the white is often heavily mottled, as on the bird in the center here. Some third-year birds (sub-adult II) retain the white belly, while others go dark; this is where identification becomes most uncertain, although in flight SA IIs tend to have trimmer-looking wings than SA Is, who typically have more raggedy trailing edges due to moulted feathers. Beaks are still dark but the eyes gradually lighten.

SA II in flight: belly light brown but giving a whitish impression (again, this characteristic can vary), trailing edges of wings clean and even.

By their fourth year (sub-adult III), most baldies start getting some white feathers on their heads, but with a vaguely osprey-like mask crossing the eyes. This bird is a classic SA III, and as you can see its tail feathers also show some white.

This photo is of a mixed-age group; the bird in the foreground (with neck extended, looking like the Seattle Seahawks logo) and the bird following behind it are both SA IIIs. At the far right, and almost hidden behind the two younger birds at the left, are two sub-adult IVs. In their fifth year, these birds have yellow eyes, yellow bills, and almost adult plumage—recognisable even to non-birders as bald eagles—but their heads retain a few dark feathers, mostly behind the eyes, and though it's not visible here, their white tails probably have a few dark smudges. As if to balance things out, they retain just a few white feathers amidst their otherwise dark brown body plumage.

These two eagles (I love this shot) are adult birds—but the faint smudges on their white heads and tails mark them as young adults, probably in their sixth year. While some adults attain their definitive plumage at this age, others may not be picture-perfect until they are seven or eight years old.

Now this bird has arrived.

Okay, quiz time. Can you identify these eagles? My answer will be in the comments section below.

Thanks to my wife, travel partner, and photographer, Jessica Farrell-Churchill. You were right, Jessa, it was worth driving back around.