Hawk in tree, Colorado front range (1 Viewer)

[tenex]

While walking on our street a few days ago we passed a bird high up in a tall old tree making quite a racket, with a series of regular sharp calls and occasionally something more complex. (I should have posted this immediately while the sound was fresher in my memory.) At first I thought Flicker, but the sound was deeper(?) and even without bins we could see it was a medium-sized raptor with a dark head, streaky breast, and powerful white legs. My best guess was Cooper's Hawk, for which Sibley does describe "flat nasal barks"... so two questions: is this ID likely correct? And in any case why would this hawk have been so noisy, behavior I don't associate with a raptor? (There was no sign of a nest.)

 

[tenex]

...anyone?...

 

[nartreb]

I can't tell the species from your description of the bird's appearance. I trust it was a bird of prey and not, say, a heron, but I can't tell which one. A hawk would fit the description well (streaky breast and white legs should rule out vultures or young eagles, dark head should rule out osprey) but did you consider, say, an owl?
I'm sceptical about it being a cooper's - you're not too likely to see "powerful white legs" on one of those. A larger hawk (red-tailed for example) might be a better fit.
There are several raptors that make lots of noise, and they mostly sound similar to my ears, but maybe your ear is better than mine. You can to a site like xeno-canto.com and have a listen to various hawk species.

I don't know why it would be making noise. Young hawks are extremely noisy when requesting food from their parents, but I think it's too early in the spring for that.

 

[tenex]

Luckily, we saw what really must be the same bird high up in the adjoining tree this evening. Had a good view with binoculars and from the rear this time: overall dark brown, a medium-sized hawk with a long thin striped tail. Juvenile Cooper's. I listened to a few recordings of its "barking" or "series call" on xeno-canto and that's exactly what we heard that day. We had just never heard anything like it before from a hawk. The note on one recording sounds just like my own question:
"an immature (probably a female) perched in a cottonwood at medium height, moving around in the tree and looking down and calling, cocking its tail and sometimes holding its wings out; I never did figure out why it was excited; it was calling for quite a while"