Cougars hunt smaller prey to avoid conflict with other predators

Yellowstone National Park is often seen as a showcase of raw, wild nature. But beneath its stunning landscapes lies a subtler drama. Here, wolves, bears, and cougars – three of North America’s top predators – navigate not just the challenge of hunting prey but of sharing space.

They all rely on overlapping food sources, especially large ungulates like elk. What happens when those resources become scarce?

Conventional ecological theory suggests that fewer prey animals should spark more intense competition. Dominant predators like wolves and bears are expected to push out subordinate ones like cougars.

However, a new study from the University of Minnesota challenges that assumption. The researchers discovered that it’s not just the abundance of prey that matters – but how big that prey is.

Cougars downsize their dinner

Over 23 years of data reveal a strategic shift by Yellowstone’s cougars. As elk numbers declined, predators like cougars began hunting smaller prey more frequently.

Mule deer, along with other medium and small species, became more common in cougar diets. The smaller kills come with advantages. They take less time to consume and are less visible, reducing the chance of theft by larger carnivores.

“This work really showcases the complex ways large carnivores make a living,” said lead author Jack Rabe, a graduate student in the College of Food, Agricultural and Natural Resource Sciences.

From 2016 to 2022, 37.6% of cougar kills were deer, compared to just 13.8% during the 1998–2005 period. Elk kills dropped from 74.2% to under 50 percent.

Cougars increasingly targeted elk calves rather than adults, further reducing handling time. This allowed them to eat more quickly and retreat before wolves or bears arrived.

Displacement and the cost of being caught

When dominant predators arrive at a cougar kill, they often force the cat to flee. That process, known as displacement, has serious consequences.

Cougars lose over 60% of the carcass when chased off, forcing them to hunt again much sooner. Kill intervals – the time between one successful hunt and the next – shorten from 5.6 days to just over 4.

Despite increasing wolf and bear numbers, displacement rates have actually declined. This runs counter to classic theories. But carcass size provides the missing link.

Smaller kills are less visible, quicker to consume, and often made in terrain where wolves and bears struggle to follow. That means fewer confrontations and more food retained by the cougar.

Prey choice helps predators coexist

“We found that shifting cougar behavior is likely a key factor in the ecosystem’s stability,” said Rabe.

“By opting for smaller prey, cougars reduce the amount of time they spend hunting to make up for kills lost to other carnivores. This allows them to maintain a relatively stable kill-rate, which in turn contributes to the overall balance of the predator-prey dynamics in the park.”

This behavior not only protects cougars from losing meals, but also stabilizes their role in the ecosystem. Even though elk populations have fallen, cougars still manage to maintain their kill rates.

That means they continue controlling deer and smaller ungulate numbers, while reducing risk of direct conflict with larger predators.

Prey size controls predator conflict

The study found that carcass size – not prey density – was the strongest predictor of interference. Larger carcasses attracted more wolf and bear activity.

Displacements were 1.67 times more likely with each standard increase in prey size. Yet smaller kills, often weighing under 40 kg (about 88 pounds), drew far less attention.

This means cougars that kill smaller prey lose fewer meals. In turn, they can avoid the energy costs of defending kills or relocating frequently. Even predator-rich areas become manageable if cougars target the right kind of prey.

The result? Less kleptoparasitism, fewer fights, and more peaceful coexistence.

Evolving diets in a crowded landscape

Wolves and bears are adapting too. Wolves now hunt bison more often, especially in winter.

From 1998–2005 to 2016–2022, bison rose from 10% to nearly 50% of the wolf diet. Bison favor open plains, far from the rough terrain preferred by cougars. This shift has reduced overlap between these predators.

Bears, though still frequent visitors in spring and summer, also showed a drop in displacement incidents. The rougher the terrain and the smaller the carcass, the lower the chance of a bear showing up.

These changes show how prey choice shapes not only predator behavior, but the structure of the entire ecosystem.

More than food: Risks and reproduction

Displacement affects more than just dinner. For cougars, being forced off a kill also carries lethal risks. Though rare, wolf attacks can kill cougars.

Two radio-collared cougars were killed by wolves between 2016 and 2022, both in terrain with poor escape options. By hunting smaller prey and staying mobile, cougars avoid such danger.

Interestingly, female cougars benefit even more. They kill smaller prey than males and are less likely to be displaced. Because females are crucial for reproduction, this strategy may support cougar population stability over time.

Smaller prey means smaller meals, but more consistent access – an important tradeoff in a competitive environment.

Diverse prey helps predators stay stable

​This study helps reshape how ecologists understand predator guilds – groups of predators that share space and food sources. The Yellowstone Wolf Project, Yellowstone Cougar Project, and the University of Minnesota team demonstrate that prey diversity supports predator diversity

When ecosystems support a variety of prey sizes and types, predators adapt rather than fight. That flexibility, not aggression, helps maintain balance. Yellowstone offers a real-world case where smart choices by subordinate predators help everyone thrive.

As wolves hunt bison and cougars switch to deer, Yellowstone’s food web becomes more resilient. This insight may prove valuable far beyond the park, especially as predator and prey populations shift around the world.

The study is published in the journal Communications Biology.

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