Buzzards are a harbinger of death and destruction. However, Cooper (1982) points out that as scavengers, the "represent purification," and thus are also positive symbols. This can also be seen in novels such as Canticle for Leibowitz, wherein the destruction inevitably leads to a sort of purification, and can be religious in conjunction with the shark/fish.
Buzzards were also once thought to be female (with hawks and eagles as their male counterparts), and thus can be symbolic of a "feminine, maternal principle" (Cooper, 1982).
(Related entry: BIRDS)