July 18, 2012; Specimen Ridge, Yellowstone National Park.

From Wikipedia:
The Accipitrinae is the subfamily of the Accipitridae often known as the "true" hawks, including all members of Accipiter and the closely related genera Melierax, Urotriorchis, Erythrotriorchis and Megatriorchis. The large and widespread genus Accipiter includes goshawks, sparrowhawks, the Sharp-shinned Hawk and others. They are primarily woodland birds that hunt by sudden dashes from a concealed perch, with long tails, broad wings and high visual acuity facilitating this lifestyle. In light of recent genetic research, the kites of the traditional subfamily Milvinae may also belong to this group.
Hawks, including the accipitrines, are believed to have vision several times as sharp as that of the human species, in part because of the great number of photoreceptor cells in their retinas (up to 1,000,000 per square mm, against 200,000 for humans), a very high number of nerves connecting the receptors to the brain, and an indented fovea, which magnifies the central portion of the visual field.