What Does a Hippopotamus Eat? Diet & Feeding Habits

Hippopotamuses are overwhelmingly herbivores that eat grass. Despite their massive size and fearsome reputation, the common hippo feeds almost entirely on short grasses and other terrestrial plants, consuming roughly 35 to 40 kilograms of vegetation per night. Their diet is surprisingly monotonous compared to what you might expect from a two-ton animal, and the way they process that food reveals a digestive system unlike almost any other large herbivore on the planet.

Grass First, Everything Else a Distant Second

Field studies consistently show that grasses from the family Poaceae make up the bulk of a hippo’s diet. Research in Ethiopia’s Dhidhessa Wildlife Sanctuary found that Poaceae accounted for about 60% of the plants hippos consumed, even though the animals were documented eating 34 different plant species across 12 families.¹ The most frequently eaten single species in that study was cattail (Typha latifolia), followed by the grass Eriochloa fatmensis. That cattail finding is a useful reminder that hippos do not limit themselves purely to grasses. They will eat sedges, aquatic vegetation, and various herbaceous plants when available.

What hippos do not typically eat is equally telling. They rarely browse on woody vegetation such as tree leaves or bark, and fruit plays no meaningful role in their diet. Occasionally, observers have documented hippos scavenging meat from carcasses, including other hippos, but these incidents are rare enough to be considered abnormal behavior rather than a dietary pattern. The standard hippo is a grazer, not a browser, an omnivore, or a scavenger.

How and When They Feed

Hippos spend most of the day in or near water, resting and socializing. Feeding happens mainly at night. After sunset, they haul themselves onto land and walk to grazing areas, typically staying relatively close to their home river or lake. GPS-tracking studies have found that the average distance a hippo travels from its river is about half a kilometer, with individual averages ranging from roughly 200 meters to 700 meters. The farthest any tracked individual wandered was 4.7 kilometers from the water.² Dominant males tend to push slightly farther from the river during wetter seasons, when green grass is available at greater distances.

This nocturnal commute typically lasts four to five hours, and hippos follow well-worn paths between the water and their preferred grazing spots. They crop grass with their wide, muscular lips rather than using their teeth to bite it off. The lips work like a lawnmower, pulling vegetation close to the ground. Their enormous incisors and canines are not feeding tools at all. Those teeth serve as weapons for fighting other hippos and deterring predators. Chewing and grinding of food happens with their molars and premolars, which show wear patterns consistent with heavy side-to-side jaw movement to break down fibrous plant material.³

A Stomach Built for Fermentation

The hippo’s digestive system is one of the more unusual arrangements among large plant-eaters. Hippos are not true ruminants, so they do not chew their cud the way cows or antelope do. But their stomach is far from simple. It is divided into multiple chambers: two front pouches called anterior diverticula, a large middle chamber, and a posterior chamber that secretes gastric acid. Fermentative digestion, where microbes break down tough plant fiber, takes place in the front and middle sections.⁴ This pseudo-ruminant setup allows the hippo to extract nutrients from low-quality grasses more efficiently than a simple-stomached herbivore could, though not as efficiently as a true ruminant with its specialized cud-chewing cycle.

What makes hippos genuinely strange among ungulates is how little energy they actually need. Digestion studies in captive hippos found that their digestible energy intake averaged around 0.30 MJ per kilogram of metabolic body mass, a figure described as “extremely low for ungulates.”⁵ In plain terms, a hippo burns far fewer calories relative to its body weight than you would expect for an animal its size. This low metabolic rate is probably linked to their semi-aquatic lifestyle. Spending the hot daylight hours floating in water, where buoyancy supports their weight, means they expend very little energy on movement or thermoregulation during most of the day. They only really have to “work” during their nighttime feeding walks.

Why the Low Metabolism Matters for Captive Hippos

That low energy demand has a direct and practical consequence in zoos. In the wild, a hippo eats large quantities of low-calorie grass. In captivity, zookeepers often supplement hay with pelleted commercial feeds that are much more energy-dense than wild grass. The mismatch between the hippo’s thrifty metabolism and those calorie-packed pellets makes hippos particularly prone to obesity in captive settings.⁵ Modern zoo nutrition programs now aim to replicate the wild diet more closely by relying on hay and fresh grasses rather than concentrated feeds, and by controlling portion sizes carefully. Fruits and vegetables, which many zoo visitors associate with hippo feeding time, are typically offered in small amounts as enrichment rather than as dietary staples.

Diet Shifts Over Time and Across Landscapes

Although hippos are confirmed grass specialists, the balance between types of grass and other plants in their diet can shift depending on what is available in the landscape around them. A study tracking changes in hippo diets around Uganda’s Queen Elizabeth National Park found that the proportion of C3 herbaceous plants (broad-leaved vegetation, as opposed to tropical grasses) in their diet rose substantially over several decades. In the 1960s, less than 20% of the diet came from C3 plants, but by the 1980s and 1990s, that share had climbed to 30-45%.⁶ The researchers linked this change to a collapse in the populations of elephants and other large herbivores in the area, which allowed shrubby, broad-leaved plants to encroach on open grassland. Hippos simply ate what was there.

The evolutionary record tells a similar story of flexibility within a grass-heavy framework. Fossil analysis of hippopotamid teeth spanning roughly ten million years in northern Kenya’s Lake Turkana Basin shows that hippos have always included some C3 vegetation in their diets, even as tropical C4 grasses became increasingly dominant in their ecosystems. C4 grasses became the majority of the diet (over 50%) by about two million years ago, but fossil hippos never reached a point where 100% of every individual’s diet came from C4 grasses.⁷ In other words, hippos have been “mostly grass with a side of other stuff” for millions of years, and the exact mix depends on the local vegetation.

Grazing Lawns and the Ecosystem Effects of Hippo Feeding

The way hippos eat does not just fill their stomachs. It reshapes the landscapes they live in. Because hippos return to the same grazing areas night after night, cropping vegetation close to the ground, they create and maintain what ecologists call “grazing lawns.” These are patches of short, dense grass that differ from the surrounding tall, ungrazed savanna. Reviews of hippo ecology have identified these lawns as containing distinct plant communities and influencing fire patterns, which in turn affects which woody plants can establish themselves in the area.⁸

Hippo-created grazing lawns also benefit other species. Research in West African savannas found that hippo lawns were more nutritious than ungrazed areas, both in terms of plant structure and nutrient content. Smaller antelope like the kob depended on these lawns for daily energy and protein needs, at least through the early dry season. After that point, the sward became too short to provide enough intake for the smaller grazers, but for a significant portion of the year, hippos were essentially setting the table for other herbivores.⁹ This kind of facilitation, where one species’ feeding behavior improves conditions for others, is a hallmark of what ecologists call ecosystem engineering.

The nutrient story extends into the water, too. Hippos eat on land but spend the day in rivers and lakes, where they defecate in large quantities. This daily transfer of terrestrial nutrients into aquatic systems fertilizes waterways, supporting algae growth and, downstream, fish populations. It is one of the reasons hippos are considered keystone species in African freshwater ecosystems.

When Hippos Eat Crops

Hippos do not limit their grazing to wild grass when cultivated fields are within walking distance of their water bodies. Crop raiding by hippos is a major source of conflict between people and wildlife across sub-Saharan Africa. Around Ethiopia’s Lake Tana, for instance, local residents reported that hippos destroyed maize, teff, finger millet, and rice.¹⁰ From the hippo’s perspective, a cultivated grain field is just a conveniently dense patch of grass. The animal cannot distinguish between wild and planted vegetation, and it does not need to. The calories are the same.

Crop raiding tends to peak during the growing season when fields are lush and during dry periods when natural grazing areas become sparse. Because hippos can consume tens of kilograms of vegetation in a single night, even a few nights of feeding can devastate a smallholder’s entire harvest. The economic impact creates strong incentives for retaliation, making crop raiding one of the leading threats to hippo conservation in human-dominated landscapes.

Colombia’s Escaped Hippos and Unlimited Pasture

One of the more striking modern tests of hippo feeding behavior is unfolding in Colombia, where descendants of hippos imported by Pablo Escobar in the 1980s have established a growing feral population along the Magdalena River basin. These animals occupy small cattle ponds during the day and move inland at night to graze on surrounding grasslands, following the same basic behavioral template as their African counterparts.¹¹ The abundance of livestock pasture, the lack of a pronounced dry season, and the absence of natural predators have removed most of the ecological limits that constrain hippo populations in Africa. Researchers have noted that these conditions may contribute to unusually high population growth rates.

The Colombian situation illustrates how well hippos can thrive when their simple dietary needs, plentiful grass and nearby water, are met without the competitive pressures and seasonal constraints of their native habitat. It also raises questions about the ecological consequences of hippo grazing in a landscape that never evolved with megaherbivores. Colombian researchers and wildlife managers are working to assess how hippo-created grazing lawns and aquatic nutrient loading might alter local ecosystems in ways that have no African analogue.

The Pygmy Hippo Difference

The pygmy hippo (Choeropsis liberiensis) is the only other living species in the hippo family, and its feeding habits diverge from its larger cousin in meaningful ways. Pygmy hippos live in the dense forests of West Africa rather than open savannas, and their diet reflects that habitat. They eat more fallen fruit, ferns, broad-leaved plants, and forest-floor vegetation than common hippos do. Grasses still appear in the diet but are far less dominant.

Their dental anatomy reflects these differences. Research on tooth wear patterns found that pygmy hippo canines showed evidence of a lateral component in jaw movement that was absent in common hippos, suggesting differences in how the two species process food.³ Pygmy hippos are also more solitary and do not create the dense grazing lawns that common hippos are known for. Their ecological footprint is correspondingly smaller, though they face far greater conservation threats due to habitat loss in their limited forest range.

Captive digestion studies found that pygmy hippos and common hippos have broadly similar metabolic demands relative to body size, with both species showing the same unusually low energy intake for ungulates.⁵ So the thrifty metabolism appears to be a family trait rather than something unique to the common hippo’s semi-aquatic lifestyle, which complicates the assumption that water-living alone explains the low energy budget.

Seasonal Stress and Dietary Flexibility

Drought and seasonal drying can squeeze hippo populations hard. As water levels drop, hippos aggregate in smaller and smaller pools, which increases competition for both aquatic resting space and nearby grazing areas. Research has documented that hippos alter their grouping behavior and movement patterns to cope with density-dependent drought effects.¹² During prolonged dry spells, grazing lawns near water can become overgrazed, and hippos may be forced to walk farther for food or switch to less preferred plant species.

Tracking data supports this pattern. The one individual in the spatial ecology study that showed migratory behavior made upstream movements of 3 to 15 kilometers during the driest parts of the year, far beyond the typical half-kilometer average grazing distance.² These longer migrations likely reflect a search for adequate food when local resources are depleted. For populations facing increasing drought frequency due to climate change, the tension between water dependence and food availability is expected to become more acute. A hippo cannot stray too far from water during the day without overheating, but the grass it needs may be receding farther and farther from reliable water sources.

How Much a Hippo Actually Eats

A common claim in popular sources is that hippos eat about 40 kilograms (roughly 88 pounds) of grass per night. That figure is reasonable but somewhat imprecise. Captive feeding studies measured dry matter intake, not total fresh weight, and found averages around 35 to 37 grams per kilogram of metabolic body weight per day for both common and pygmy hippos.⁵ For a large adult common hippo weighing 1,500 kilograms or more, that converts to a substantial pile of dried plant matter. Fresh grass, which contains a high proportion of water, would weigh considerably more. So the 35-to-40-kilogram figure probably refers to fresh weight and is in the right ballpark, though wild intake is harder to measure directly than captive intake.

Relative to body size, though, hippos eat modestly. A cow of similar weight consumes a much larger proportion of its body mass in food each day. The hippo’s low metabolic rate means it simply does not need as many calories. This metabolic frugality is one of the traits that allows hippos to sustain their enormous bulk on a diet of plain grass, without needing the higher-calorie browse, seeds, or fruit that other large mammals often depend on.