I got these shots with the rented 400mm telephoto lens, while out in San Francisco. He was perched on a telephone pole about 100 feet away. In the image below, the background you see is a portion of the Golden Gate bridge.
I had to ask Roger for help identifying him but even he had a hard time of it.
It’s a tough call. I’m guessing you saw this in California … Most places in the country, the most common hawk is the Red-tailed, and that’s probably what this is, but I can’t say for sure. It looks like the beak is deformed, which means it might have trouble finding food and perhaps has resorted to eating garbage, which could discolor it’s bill and feathers. I think it’s an immature, which makes the plumage more confusing. And there are various degrees of melanism (the opposite of albinism) which are fairly common in the West. So, if you have a melanistic immature that’s been digging in garbage, it won’t look typical at all. Other possibilities are Rough-legged or Red-shouldered.
I’m going with Red-tailed.