Scavenging birds (Figure 1c, 2g) recycle carcasses, lead other scavengers to dead animals [79], maintain energy flows higher in food webs [80] and limit the spread of diseases and of undesirable mammalian scavengers [9]. Vultures are the only known obligate vertebrate scavengers
(Figure 2g) [18] and, in many ecosystems, are (or were) the main meat-eaters owing to their efficiency in finding and consuming dead animals [79]. Vultures have an impressive ability to resist and possibly detoxify bacterial toxins in rotting flesh. Extremely acidic secretions of the vulture stomach (pH = 1) can kill all but the most resistant spores, significantly reducing bacterial sources of infection from consumed carcasses