Scavenging For Health

We might find the eating habits of vultures distasteful: they feed on rotting carcasses. But as the flying scavengers face declines around the world, some researchers are worried about a possible side-effect – more disease among the mammals that take their place.

Vultures “are the most threatened avian functional group in the world,” an international research team notes in Conservation Biology. Numerous species are in decline, meaning that carcasses sometimes sit longer before being devoured. That potentially means dangerous microbes get more of a chance to thrive in the rotting flesh. It also means that other animals, such as feral dogs, rats and other mammals, get more of a chance to seize a meal. That shift, however, “could increase rates of transmission of infectious diseases, with carcasses serving as hubs of infection” where lots of animals come into contact with each other, the researchers note.

To test that idea, the researchers set out carcasses at 54 sites in central Kenya, and then watched what happened. In some cases, they put the dead animals under trees, in order to exclude local vultures, which hunt by sight. Overall, they recorded more than 1009 vultures at carcasses, and 544 animals of other types, including tawny eagles and spotted hyenas. Leopards, lions, and mongooses also stopped by for a snack.

When vultures were excluded from carcasses, “the mean number of mammals at carcasses increased 3-fold (from 1.5 to 4.4 individuals/carcass),” and the number of interactions between different mammal scavengers also tripled. Although the researchers didn’t directly look for disease, they conclude that the increased interaction does suggest the disappearance of vultures could “affect patterns of disease transmission among mammalian carnivores.” David Malakoff | March 26, 2012

Source: OGADA, D., TORCHIN, M., KINNAIRD, M., & EZENWA, V. (2012) Effects of Vulture Declines on Facultative Scavengers and Potential Implications for Mammalian Disease Transmission. Conservation Biology, no-no. DOI: 10.1111/j.1523-1739.2012.01827.x 

Image © Michael Elliott |