Thursday, December 24, 2009

Hawks in My Yard

Ahhhhhhhh... the magic of PhotoShop!
Okay, the other day I had two visitors... Each landed on a different part of the same pole and I got photos of both. Here you can see the two birds a 'PhotoShopped' image. Yes, I did not spend the time to ensure the photos were exact; the bird on the left appears slightly smaller than it can see on the right of that image (where the pole 'meets' the rest of the pole in the photo on the right), that it is really too small. That said...size really doesn't matter here; in both species the female is considerably larger than the male and there are slight differences in size between all birds in a species (just like with people and other animals).

Still, this affords us a place to begin looking at the two birds. It was my belief that these are both Sharp-shinned Hawks...partly because of their size (I know that's rife with problems); they were both about 12" long. Part of my decision was with regard to their tails...both of which seem identical to me...and sort of square. No?

My problem is that a very well respected friend of mine has suggested one is a Cooper's and one is a Sharp-shinned. She did NOT have benefit of this spiffy image, however...and I greatly appreciate her willingness to discuss the differences in the birds with me. I thank her again!

I have done some research using all my various Field well as the more technical work in Cornell's The Birds of North America-Online. There I learned specifically:

Cooper's Hawk:

The Cooper’s Hawk is a crow-sized hawk with short, powerful, rounded wings and a relatively long tail. Males markedly smaller than females; total length 16.5” with weight at about 1-pound.

Barred rufous underparts in adults, streaked brownish underparts in immatures. In adults, dark blue-gray crown contrasts with lighter-colored nape.

Tail with 4 straight alternating bands of dark and light brown or blue-gray in adults; brown tail bands in immatures. Tail white-tipped.

Legs yellow; iris yellow in younger birds, orange or red in older birds

Sexes similar in plumage, but males, on average, more brightly colored than females. Back and upper wing coverts brown to blue-gray in adults.

In Juvenal plumage, back and upper wing coverts medium brown with some white mottling and rufous feather edging.

Sharp-shinned Hawk:

Sharp-shinned Hawk is a small, slender, feisty accipiter, with short, rounded wings and a long, narrow tail. Length is 11” and weight at about 5-ounces.

In adult male upperparts, including wings and tail, bluish gray to slate, becoming slightly darker on the crown.

Tail crossed by 3–5 visible slaty bands and narrowly tipped white. Tail usually appears square in shape when folded, but often appears slightly rounded when spread.

Wings relatively short and rounded. Legs and toes yellow, long and sticklike with tarsometatarsus laterally compressed, hence the name “sharp-shin.”

Adult plumages similar throughout year.

Adult eyes red, juveniles pale yellow.

Open wing appears dark above but whitish below with remiges boldly banded with black. Underparts primarily whitish and heavily barred with rufous or tawny on breast, belly, side, and flanks.

Adult female similar in coloration, but upperparts more brownish olive and underparts less heavily barred than in males.

In juveniles, head heavily streaked grayish brown and white or grayish brown and tawny on crown, nape, and sides of neck, with a pale superciliary stripe. Back, rump, and wings dark brown to dark brownish gray, with back and wing-coverts margined paler. Occasional white feather bases show on back and wing-coverts. Underwing white and boldly barred with dark brown. Tail as in adults but gray often replaced by brownish. Underparts white to cream with broad dark-brown streaking on breast, belly, side, and flanks.

Okay...HOW is one to really manage this? To top things off, I just learned (though my friend has mentioned it in passing), there is a third hawk that adds yet more confusion to the mix: the juvenile version of the much larger Northern Goshawk! Here we go:

Field identification difficult owing mostly to similarity with smaller Sharp-shinned Hawk and the larger Northern Goshawk in Juvenal plumage.

Cooper’s have more rounded tails than Sharp-shins or Goshawks, but difference appears slight.

White terminal tailband wider in Cooper’s than in Sharp-shins.

The Sharp-shin’s head barely projects beyond its “wrists” when gliding; in Cooper’s the head projects far beyond “wrists.”

In immatures, streaking tends to end somewhat higher on the belly in Cooper’s than in Sharp-shins.

Crown color contrasts with nape in adult Cooper’s more so than in Sharp-shins.

In Juvenal plumage, the bars on the rectrices are nearly aligned in Cooper’s but offset in Goshawks, creating a zigzag effect.

Undertail coverts streaked in Juvenal plumaged Goshawks; white and not streaked in Cooper’s. I seriously wonder if I'll ever get it right! LOL But tell me, with the above 'Shopped' photo; what say you now? Please leave your comments, won't you?

Resource (which I quoted liberally): Cornell's The Birds of North America-Online.
The photo at mine.

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