"Fri-D"

"Wait, that's a Spotted? It doesn't have spots." How many birders have uttered those words, which my son Tim applied to the bird above?

Among the rules of shorebird I.D. is this one, and learn it well:  

If you are going to use plumage to identify a shorebird, you have to age it first.

So there are at least two ways to age shorebirds. One, ironically, is know that juvenile Spotted Sandpipers look like this and so there you go - which means you already knew what the bird was and didn't have to identify it in the first place!

The other way is to look at condition of feathers and for certain patterns characteristic of juvies. As to the latter, the uniform edging to the upperpart feathers creates a scalloping or scaly effect on many juvenile shorebirds, including this one - such edges are much thicker on some species, e.g. on juvenile peep.

The uniformity is key to aging, too, the uniformity of the pattern and the uniform great condition of the feathers. They're in great condition because they're all fresh - every single one of them grew in more or less at once as the bird went from a downy fuzzball to its first full set of grown-up feathers, probably sometime in June or early July, somewhere north of Taylor Sound, Cape May, NJ, where this bird was photographed last weekend. Never again will this bird grow a set of feathers all at once - so never again will each feather be in the same fresh condition the way they are now.

The trouble with this feather condition business is that you have to be close to the bird with great optics to use it. Which is why we i.d. Spotted Sandpipers by their size (slightly larger than peep), short legs, relatively long neck, short bill, and active tail bobbing. 

By the way, "Fri-D" posts like this one will, I hope, join Wordless Wednesday and Thoughtful Thursday as regular occurrences here. Let me know what you think!