The Turkey Vulture, also known as turkey buzzard (or just buzzard) can do both, poop and vomit. Feces and urine are combined and voided through a single opening called a cloaca. It is the common passage for urine, feces, sp3rm and eggs in birds.
They have a terrific digestive system, its digestive juices kills bacteria which is why vultures don't get sick from eating rotten meat-- defecating on their legs might even work as an antiseptic wash!
Vultures direct the cloaca downward and forward to defecate on its bare legs or feet. Just as with sweat, the liquid feces evaporate and the vulture is made cooler. The scientific term for this manner of behavior is called urohidrosis.
Of interest, if you see a motionless turkey vulture in Marin County that appears to be dead, or nearly so, hold off on plans to schedule a memorial service, as the bird may be in a poison-induced coma. Find out more at sfgate.com.