Looks like a male Cooper's hawk because of its smaller size, although there is no definitive reference in your photo to reckon scale, therefore I'm assuming that the broken trunk is probably nor more than 12" in diameter for it to be so rotten, thereby making the accipiter rather smallish. The gals are much bigger in body length and girth. Also, the girls have dull greyish-brown backs, while the more diminutive males are steely blue as your bird appears to be. It's quite common for female birds to be larger than male birds and this sexual dimorphism is especially pronounced in this species. In humans the male is usually bigger and the female is usually smarter. Harry Belafonte taught me that. He's 96 years-old and he learned about smart women back when he was still a young man. Besides, it's blatantly obvious that women are smarter when one is fortunate enough to be in the company of women, even if it makes one feel stupid afterwards. At least that's what I've heard.
