Buzz
Despite their massive size, intimidating tusks, and aggressive behavior, hippos are primarily herbivores. While they occasionally attack humans or clash with crocodiles, they are not considered predators or carnivores—or are they?
Biologist Joseph Dudley suggests that hippos are not as strictly herbivorous as once thought. Despite their adaptations for grazing and plant-heavy diets, hippos have been observed consuming meat. Reports from scientists and amateur observers (note: NSFW graphic images) document hippos attacking, killing, and eating other animals, scavenging carcasses, and even stealing prey from predators. In a new study published in Mammal Review, Dudley and his team argue that such carnivorous behavior is not rare or limited to specific hippo populations. Instead, it appears to be a widespread phenomenon with significant implications for the species.
Evolution has equipped hippos and other large herbivores with digestive systems optimized for processing plant matter. However, this doesn’t preclude them from consuming meat. Many herbivores, such as antelope, deer, and cattle, occasionally eat carrion, birds, eggs, or small mammals. According to Dudley, the primary barrier to frequent carnivory in these animals is not their digestive systems but their physical limitations in capturing and consuming prey. Hippos, however, are uniquely equipped to overcome these challenges, making their carnivorous behavior more feasible.
THOSE WHO CAN, DO
Dudley and his team note that the hippo’s massive size and unique dental structure make it uniquely capable of preying on and scavenging large mammals, unlike other herbivores. Their territorial and aggressive nature further enables carnivorous behavior, often leading them to kill and consume other animals.
Since Dudley’s first scientific record of hippo carnivory in 1996, numerous instances of hippos eating meat—and even cannibalizing—have been documented. Wild hippos have been observed feeding on impalas, elephants, kudus, wildebeest, zebras, and even other hippos, whether they killed the prey themselves or scavenged from predators. Such behavior occurs during droughts when food is scarce, as well as opportunistic moments, like mass drownings of wildebeest during river crossings. Captive hippos in zoos have also been known to kill and eat tapirs, wallabies, flamingoes, and pygmy hippos.
The team emphasizes that carnivory in hippos is not limited to specific individuals or populations but is an intrinsic aspect of their behavioral ecology, supported by scientific records and observations from various researchers.
EATING MEAT WHILE WE SLEEP
Why did it take so long to uncover this behavior? One reason is the hippo’s nocturnal habits, which keep their dietary activities, including meat consumption, hidden from human observation. Dudley believes their carnivorous tendencies have simply gone unnoticed.
This behavior may also explain why hippos are particularly vulnerable to anthrax, suffering higher mortality rates during outbreaks. Researchers suggest that hippos are exposed to the disease in two ways: through ingesting or inhaling bacterial spores from plants and soil, like other herbivores, and by consuming contaminated carcasses. Cannibalism during outbreaks further increases their risk.
The link between carnivory and anthrax outbreaks in hippos has significant implications for disease control and the protection of both animals and humans. During wildlife anthrax outbreaks, human infections often result from handling or consuming contaminated “bush meat.” For instance, a 2011 outbreak in Zambia led to 511 human anthrax cases and at least five deaths linked to infected hippo meat. Proper disposal of infected carcasses, such as burying or burning them, is crucial in hippo habitats to prevent further exposure to both humans and hippos.
