Carnivores that shape their lives around humans may find themselves following human calendars. And that includes our religious observances. In Ethiopia, spotted hyenas eat meat scraps left by humans for most of the year. But when those humans go vegan for Lent, the hyenas become hunters.
You might not expect dietary discretion from spotted hyenas, as they're possibly the world's least picky eaters. They're just as happy to scavenge on found carcasses as to kill their own meat. They've been observed devouring all kinds of mammals, birds, fish, and reptiles--not to mention garbage, dung, and carcasses infected with anthrax spores. The hyena's digestive system even handles bones without a problem. Hair and hooves are the only remains left after a thorough hyena meal.
But in northern Ethiopia, where populations of their natural prey are severely depleted, spotted hyenas rely on humans for food. Not that they eat humans, that is. Hyenas scavenge animal remains that Ethiopians dump outside their compounds, and since they stay away from the people supplying those carcasses, human and hyena tolerate each other's company. (At a veterinary school, humans even count on hyenas to keep the campus clean.)
There's just one hitch for the hyenas. The population in this part of the country is primarily Orthodox Christian. The Ethiopian Orthodox Tewahedo Church dictates fast periods throughout the year, the most prolonged of which is the eight-week Lent. During this period, Christians give up all meat, dairy and eggs to follow a vegan diet.
Researchers led by Gidey Yirga at Ethiopia's Mekelle University set out to see how the Lenten fast affected local hyenas. At sites around Mekelle, they collected hyena scat on the first day of Lent (representing what hyenas ate beforehand); the last day of Lent (for what they ate during the fast); and 55 days later (after a return to their normal diet). By digging animal hairs out of the hyenas' feces, researchers could identify the species that had made up their meals.
A wide variety of animals were represented in the hyenas' dung, including livestock such as sheep, goats, donkeys, cattle, and horses. (In the study areas, livestock outnumber humans.) And the hyenas' diet had significantly changed during Lent. With their usual supply of leftovers lacking, hyenas' scat showed that they had feasted on donkey meat.
The authors explain that live donkeys are an easy target for hungry hyenas because, unlike other livestock, their owners leave them outside the compound at night. Additionally, "weak donkeys are abandoned altogether, which makes them a relatively easy food source."
With plenty of hapless donkeys around, the hyenas weren't exactly facing hardship during Lent. But they adjusted their behavior with impressive ease. During Lent, the hyenas became active hunters, taking down live animals to feed on. After Lent, they returned to scavenging trash.
The flexibility of predators such as hyenas means that removing a food source might be a good way for humans to change animals' behaviors. The hyenas in this study don't harass people too much. But when the predators hanging around your city (or your livestock) are lions, it can help to know how to get them on a different diet.
Hyenas' adaptability also means humans aren't the only ones that can follow a different diet from one calendar period to the next. But outside of the fasting seasons, hyenas are probably relieved to get back to the comfort of a pre-killed meal. And when Easter arrives, the donkeys might be the happiest of all.
Yirga, G., De Iongh, H., Leirs, H., Gebrihiwot, K., Deckers, J., & Bauer, H. (2012). Adaptability of large carnivores to changing anthropogenic food sources: diet change of spotted hyena (Crocuta crocuta) during Christian fasting period in northern Ethiopia Journal of Animal Ecology DOI: 10.1111/j.1365-2656.2012.01977.x