House cats living in the wild eat almost entirely small mammals and birds. Their diet breaks down to roughly 50% voles, 20% mice, and a mix of other rodents, birds, reptiles, and insects. This makes them true obligate carnivores, meaning they cannot survive on plant-based food and depend on animal tissue for nutrients their bodies can’t produce on their own.
What Wild Cats Actually Hunt
Feral domestic cats are opportunistic predators that will eat whatever small animals are available, but rodents dominate the menu. Studies of feral cat diets in Hungary found voles alone made up nearly half of everything consumed, with mice accounting for another fifth. The remaining portion was a rotating mix of birds, shrews, and other small mammals, with the exact proportions shifting based on habitat, season, and what prey happens to be abundant.
Insects show up in wild cat diets too, but they’re nutritionally insignificant. Beetles, grasshoppers, and other invertebrates contribute less than 0.5% of total food intake by weight in most studied populations. Cats clearly catch and eat bugs, but they’re more of a snack between meals than a food source that matters.
Globally, the scale of cat predation is staggering. Free-ranging domestic cats in the United States alone kill an estimated 1.3 to 4.0 billion birds and 6.3 to 22.3 billion mammals every year, with unowned feral cats responsible for the majority of that toll.
How Often They Hunt and Kill
Feral cats are relentless but inefficient hunters. Research using animal-mounted video cameras found that cats succeed in only about 30% of their hunting attempts. That still adds up to roughly seven kills per day per cat, which is what it takes to meet their caloric needs from small prey. A single mouse doesn’t contain many calories, so a wild cat needs to hunt almost constantly during its active hours.
Habitat matters. Cats are significantly more effective hunters in open environments where prey has fewer places to hide. In dense vegetation, success rates drop, which means cats in those areas need to attempt even more hunts to get the same amount of food.
The Nutritional Profile of a Wild Diet
The natural diet of a feral cat is extremely high in protein and fat, with almost no carbohydrates. Researchers estimating the nutrient intake of free-roaming cats found that 52% of their daily energy comes from protein, 46% from fat, and just 2% from carbohydrates. That 2% figure is striking when you consider how many commercial cat foods contain 30% or more carbohydrate content from grains and fillers.
This protein-heavy diet isn’t a preference. It’s a biological requirement. Cats lack certain metabolic pathways that other animals use to synthesize essential nutrients from plant sources. They need preformed versions of specific amino acids, fatty acids, and vitamins that only exist in animal tissue. Taurine is the most well-known example. It’s critical for heart function, vision, and reproduction, and cats can’t make enough of it internally. In prey animals, taurine concentrations are highest in the heart and lungs, while organs like the liver and kidneys contain far less. This means a cat eating a whole prey animal gets taurine from specific parts of the carcass, not evenly from all of it.
Beyond taurine, whole prey provides a complete amino acid profile. When researchers analyzed the amino acid content of prey species commonly eaten by cats in California, they found that whole carcasses exceeded recommended levels for every essential amino acid, regardless of species.
How Wild Cats Stay Hydrated
Cats in the wild rarely need to drink standing water. Fresh prey is roughly 65 to 75% moisture by weight, and cats have evolved to extract most of their hydration from the water already present in their food. They can also use metabolic water, which is produced as a byproduct of digesting protein and fat. Research has documented that cats can survive on preformed and metabolic water from food alone for months without needing a separate water source.
This is one reason many veterinarians note that cats fed exclusively dry kibble (which contains about 10% moisture) tend to live in a state of mild chronic dehydration compared to cats eating wet food.
What Happens to Bones, Fur, and Feathers
Wild cats eat their prey whole or nearly whole, which means they’re swallowing bones, fur, feathers, skin, and cartilage along with the meat. These indigestible materials, sometimes called “animal fiber,” serve a purpose similar to plant fiber in human diets. They pass through the stomach and small intestine largely intact, then reach the large intestine where gut bacteria partially ferment some of them. The rest moves through as bulk, helping push waste through the digestive tract.
Cats have a relatively short colon compared to omnivores, which limits how much fermentation can happen. Tough materials like bone fragments and dense fur may pass through with minimal breakdown. Some indigestible material, particularly hair, gets expelled the other direction as hairballs when it accumulates in the stomach.
Why Wild Cats Eat Grass
Despite being strict carnivores, feral cats regularly eat grass and other plants. This behavior has been documented in over 100 species of meat-eating mammals, including wild relatives of domestic cats. Two leading explanations exist, and both likely play a role.
The first is parasite control. Researchers have observed that fibrous plant material can physically wrap around intestinal worms, helping expel them. Wolves have been found with grasses tangled around roundworms in their scat, and a similar mechanism likely works in cats. The second explanation is hair removal. Cats swallow large amounts of fur, both from prey and from grooming themselves. Consuming rough, textured leaves may stimulate the digestive tract to push accumulated hair through before it forms a dangerous blockage. Cats and dogs are commonly observed eating grass and vomiting it back up shortly after, undigested, often with hair or other material attached.
Younger and smaller cats appear to eat plants more frequently, possibly because they carry heavier parasite loads relative to their body size and face greater health risks from intestinal blockages. Rather than a sign of illness or nutritional deficiency, plant eating in cats appears to be a normal, healthy behavior inherited from their wild ancestors.