Black Vulture

The picture isn't too clear, but even if it was, the silhouette would be the best means of identification. Based on the silhouette, it is definitely a vulture. In the case that it has white tipped wings, it is a black vulture. Often, black vultures can be seen circling an area with turkey vultures. Up close the visible differences are obvious.

*Black vultures have a milky gray head, with legs of the same color. The white-tipped wings are an obvious distinction when in flight

*Turkey Vultures have a pink head, with legs of the same color. Their wings are rather uniform in color.

The best way to tell vultures from other birds of prey is 1) The silhouettes are most often darker in vultures 2) Hawks tend to have wider tails, shaped like a widening paddle 3) Hawks tend to fly a bit higher, while vultures tend to circle lower (vulture prey is most often dead, they don't need to be quite as stealthy). The altitude of flight can vary, however.

Overall, great silhouette shot!