American Tree Sparrow, Red-Shouldered Hawk, and a mystery hawk

Sunday, I went to Riverdale to take my aunt out to lunch, and on the way I stopped for an hour's birding in Inwood Hill Park, where I ran into my first American Tree Sparrow of the year.

Tree, Sparrow

All the classic marks: red cap, bicolor bill, breast clear except for one central spot, single bold wingbar (not shown).

On the way home, I went across Central Park. Entering the Ramble, I ran into Adrian Burke, who told me there was a Red-Shouldered Hawk "just west of the Oven". We don't get to see those all that often in the City. At Mugger's Woods in the Ramble, I saw a big lump high in a tree, and it turned out to be this:

rare visitor

...a Red-Shouldered Hawk. He flew off, roughly in the direction of the Oven, and I wound up tracking him through the Ramble.

Red shoulder, see?

Now here's the funny thing. When I got to the Oven, Bruce Yolton was there with his camera set up, its enormous lens trained on a hawk in a tree just west of the Oven--well, a few steps down the path to the Riviera. "What the heck is this bird?" he asked me and another birder.

Mystery hawk

What, indeed? We couldn't quite figure it out. Clearly a Buteo by shape, but that isn't the belly band of a Red-Tail, and that tail is quite long for a Buteo (though too short for an Accipiter), and the banding is faint with thick dark bands, not the many thin bold bands of a juvenile Red-Tailed. 

another view of a mystery

Aside from the shape and tail length, when it flew out, it used not the flap-flap-glide style of an Accipiter but the fast steady strokes of, well, a Red-Shouldered Hawk.

So I think this may be an immature-plumage Red-Shouldered. If I'm right, two Red-Shouldered Hawks in Central Park at once is amazing.