As the crow flies – How mammal scavengers use birds to locate food
It has been well established that many animal species will use various types of information transfer between species to their advantage. However very little is known about information transfer across disparate species. The ability of one species to read information from unrelated species, even across family, order or class.
A recent study published in The Journal of Animal Ecology, studied the ability of mammal scavengers to utilise avian scavengers to locate a food source (Kane & Kendall, 2017) The study found that species such as jackal or hyena will actively pursue vultures and eagles as they begin to descend on a carcass. This allows the mammal scavengers to take direct advantage of the superior range of vision and visual acuity of scavenging birds. It has been shown that the jackal or hyena will both follow individual birds in a particular direction, or move toward large areas of activity above a food source.
The study also suggested that individual species were more likely to follow the behaviour of specific species to a carcass, both within and across animal classes. African White-backed Vultures were most likely to follow Tawny Eagles, Jackals followed Lappet-faced Vultures, Hyenas followed Ruppell’s Vultures and Bateleurs Eagle rarely followed any species. Many species have even been shown to follow the behaviour of one particular species, and ignore the same behaviour in a different one. Jackals were shown to rarely follow the behaviour of eagles, and were even observed running towards the same behaviour when seen in a Lappet-faced Vulture. Hyena also showed interesting species distinction, seeming to ignore eagles landing on a carcass and not move towards the carcass until vultures arrived. It appears that mammal scavengers only trust the vultures to find them food. However, it could also be suggested that the particular dietary preference of the vultures more closely matches that of the mammal scavengers. So, they are more likely to find a suitable meal, and less likely to waste a trip.
This behaviour is a definite advantage to the mammal scavengers as they have been found to locate carcasses twice as fast when using the visual cues of the birds, compared to the sound cues given of at the kill of a leopard, cheetah or lion, or by predation activity. The vulture carcasses are also possibly preferred, as the birds are likely to only remain at a carcass for a short time, due to their ability to consume prey quickly. Vultures are also only active during the day, which give the mammal scavengers more time on the kill. Finally, and perhaps most importantly, hyenas and jackal are much more likely to come into potentially conflict at the kill of a big cat, compared with one located by birds.
Birds can gain can also take advantage in finding food by following predation activity, or animals on a carcass. Another possible benefit the birds may gain is by taking advantage of the conflict between mammal predators/scavengers at a kill. It is easy to see why this sort of behaviour could evolve across species. The ability to increase survival potential is the driving force behind evolution, and taking advantage of others is the fuel to that potential. If a species is capable to even slightly increase its ability to increase access to food, decrease energy expenditure and/or reduce possible conflict, they are more likely to survive to reproduce. Making it a successful strategy, which would spread through a population quickly.
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