In a grassy clearing in the western foothills of the Peruvian Andes, a fresh donkey carcass is beginning to attract flies.

Wormed by the tropical sun, its fetid smell is rising in the air.

A turkey vulture far overhead catches a whiff, and it too is drawn to the dead animal.

Over the next week or so, the carcass will be picked apart and eaten by several species of

scavenging birds, turkey vultures, black vultures, king vultures, Andean condors, and crested

karakaras.

If you were to watch the process of all that tasty, tasty donkey meat being eaten,

you would not see all of these birds sitting around the carcass together peacefully sharing a meal. No, what you would

see are frequent squabbles or outright brawls between members of two different species,

with much pecking, clawing, and furious wing flapping. The losers of these battles wait anxiously on the periphery until the victorious birds

are done stuffing their gullets with meat.

A scientific study of this exact scenario found a dominance hierarchy among these five bird species.

By documenting thousands of bird fights at carcasses, the researchers found

that larger species tend to win fights with smaller species. The bigger you are, the more likely

you are to win. Andean condors, no surprise, are the heavyweights, the big boys in those Peruvian

foothills, so they nearly always win against the other species.

The dominance hierarchy then goes, King vulture, crested caracara, turkey vulture, and black vulture.

That's the pecking order in those parts.

Dead donkeys and other animal corpses are a precious resource for these scavenging birds.

But large carcasses aren't all that common, and they're distributed haphazardly across the

landscape.

When multiple bird species are trying to use the same vital but limited resource, it's

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