Vultures are 'eyes in the sky' for hungry hyenas and jackals
Hungry hyenas and jackals on the African plains have their own version of sat nav - looking to the sky in their search for food.
Biologists have used a combination of fieldwork and computer modelling to show that the animals use vultures to locate a carcass.
When large groups of these iconic birds descend, they present an obvious pointer to a carcass, which the mammals follow.
They are, in effect, the eyes in the sky for the mammals. This is shrewd behaviour, because the view of animals stuck on the ground is often blocked by the lie of the land.
Using this tactic allows the animals to locate a carcass nearly twice as fast as if they had to search without them.
The new work from biologists at North Carolina Zoo and University College Cork is published in the 'Journal of Animal Ecology'.
One of the authors, Dr Adam Kane of University College Cork, previously showed that vultures themselves often scrounge on the discoveries of eagles.
He said: "What we're seeing is a chain of arrivals at a carcass, where the species that arrive early on tend to be the best spotters, whereas those that arrive later tend to be the most physically dominant.
"This is important, because it means the first-comers must eat quickly before they are bullied off their dinner.
"Although both jackals and hyenas are capable hunters, a carcass doesn't fight back, so the mammals don't have to work as much as they would for a hunt.
"They have an army of vultures to contend with, but a vulture is quite a bit smaller than your average hyena. The birds can't afford injuries if they are to ever fly again, and so tend to concede their meals to the larger competitors."
By building computer models that used real-life animal data, the authors were able to predict the time that mammals should arrive at a carcass.
He added: "We know how far a hyena can see and how fast it can move, so it's simple maths to determine when it should appear at the carcass if it is indeed following the descending vultures."
Co-author Corinne Kendall, who conducted the fieldwork in the Masai Mara National Reserve, said: "Curiously, the mammals never directly followed scavenging eagles.
"Eagles have a broad diet and also eat small prey, like snakes and mice, and thus they may not be a reliable signal when searching for larger carrion that mammals are actually looking for."