A pair of Brown Goshawks proclaiming their territory.
The larger bird, presumably the female, is on the left, the male on the right. Both birds were about the same (long) distance from the camera and the images are cropped about the same, so this gives some indication of their relative sizes. The female was perhaps a tad closer, so the size difference may be slightly exaggerated.
Note how the female's tail appears to be slightly forked, possibly due to not quite fully grown new feathers. A slightly forked tail is more usual on Collared Sparrowhawks.
photo by Duncan McCaskill September 2017