I came across a bird kill in the dunes today (28 August 2012). Here are the clues (to the species identity) as I encountered them:
Note the relatively short wing (I should have measured, but I'm guessing it was ~10 inches long). The rufous edges on the smaller feathers indicate that this is a juvenile.
Beautiful barred feather patterns on the underside. The next photo shows a close-up of the innermost feathers. I love the spade-shaped markings!
After the wing, I found these feathers:
These are probably breast feathers. Note the long dark streaks along the shafts.
The next clue was helpful for identifying the type of bird:
These large talons reveal that this is raptor.
Any guesses which species?
The next two photos were taken earlier this month. They're not the best photos, but they show the species that I think is involved in the mystery above.
The two images above show a juvenile Cooper's Hawk (Accipiter cooperii) in flight and hunting in coyote brush (Baccharis pilularis). Accipiters primarily eat medium-sized birds. I'm guessing this one was chasing a sparrow (or possibly a jay — I never saw the item of interest).
I've read that Cooper's Hawks may be preyed upon by Great Horned Owls or Red-tailed Hawks, both possibilities on Bodega Head.
Before today, I had no idea that Cooper's Hawks had such handsome spade-shaped markings on the undersides of their wings!
(Now I'll always think of them when playing cards.)