For as long as there have been lions and spotted hyenas, the carnivores have competed with each other. The gore-flecked conflicts over carcasses on the African grassland are just the latest skirmishes in a carnivoran competition that has been going on since the Pleistocene.
I root for the hyenas. There’s something strangely charming about the tittering predators, and they are far more complex than the filthy scavengers they're often portrayed as. Clans of hyenas are capable of taking down prey as large as juvenile elephants as well as reducing carcasses to piles of splinters with their exceptionally powerful jaws. This combination of skills has allowed them to thrive in lands stalked by their Ice Age competitors. As Stéphanie Périquet and colleagues have found during a long-term study of hyenas in Zimbabwe’s Hwange National Park, when too many lions are around the hyenas simply change what’s on the menu.
The new study came out of observations of the park’s hyenas carried out between 1999 and 2013. And it was during the later part of this span, between 2005 and 2008, that lions made a minor comeback. A ban on lion trophy hunts around the park borders let the big cats proliferate and prowl the park in greater numbers than before, coming into greater competition with hyenas. You can see it in what the hyenas ate.
Over two study periods – one before and one during the lion surge – researchers followed groups of hyenas as they foraged and collected scat for analysis of the prey remnants inside. (The process for this latter effort involved soaking each turd in water and bleach for thirty minutes in a nylon stocking to extract the hairs inside, sun-drying those contents, and picking through them to match hair to prey species. Keep that in mind, aspiring zoologists.) What the zoologists found didn’t match their expectations.
During the first period, when there were fewer lions, the hyenas focused on hunting mid-size and large prey like zebra, kudu, and buffalo, supplemented by smaller species. Périquet and coauthors thought that competition with lions would drive hyenas to focus on small prey. That way the hyenas could finish their meals before lions would have a chance to find them and steal the carcasses. Instead, however, the zoologists discovered that hyenas started traveling in mid-sized groups and started to avoid hunting zebra and kudu in favor of feasting on elephant and giraffe carcasses.
These changes were not in proportion to the availability of prey species. The number of giraffes actually declined between the two study periods, yet the hyenas were consuming giraffe more often. Lions may have been inadvertently supplying them. While the hyenas likely killed some of the giraffes, other times the carnivores acted as scavengers. This didn’t necessarily involve running the cats off their kills. Even when they pick a body “clean”, lions still leave a wealth of meaty morsels and marrow-filled bones on a carcass. All hyenas have to do is show up as a clean-up crew.
The scavenging shift may be attributable to the way hyenas hunt. Hyenas are pretty noisy when taking down prey, Périquet and colleagues note, and this makes it all the easier for lions to find them and snatch their kills away. By traveling in smaller groups and hunting less, the Hwange National Park hyenas were able to go dark and avoid risking fights with enraged lions.
And the change worked. The hyena population, Périquet and coauthors note, remained stable even as lions moved in. Hyenas didn’t go from apex predators to dangling at the bottom of the food chain. Their magnificent jaws offered them another option, giving them plenty of reason to laugh at those pushy lions.
Périquet, S., Valeix, M., Claypole, J., Drouet-Hoguet, N., Salnicki, J., Mudimba, S., Revilla, E. Fritz, H. 2015. Spotted hyaenas switch their foraging strategy as a response to changes in intraguild interactions with lions. Journal of Zoology. doi: 10.1111/jzo.12275
[This post was originally published at National Geographic.]