Study finds solitary carnivores kill more than group hunters

Earth’s majestic “top predators” are among the world’s most prolific hunters. But which ones kill the most?

Our new research, published in Biological journalsshowed that solitary hunters like bears, tigers, and Eurasian lynx have higher individual mortality rates than social predators like wolves and lions. And smaller species, like cheetahs and pumas, tend to kill relatively more prey because their prey is often stolen by more dominant carnivores.

This information helps us better understand how different predators affect their environment. It can also guide hunting quotas and help assess the impact of humans on carnivores.

These predators play a vital role in ecosystems. Yet they are among the most endangered animals in the world. Carnivores frequently come into conflict with humans, particularly over livestock and public safety.

Our approach

Our study consisted of a systematic literature review, a world first, on the predatory behavior of large terrestrial carnivores. In particular, we examined the “mortality rates” of carnivores, that is, the number of prey killed over time. We did this to better understand their foraging and their impacts on prey populations and ecosystems.

We reviewed 196 articles that quantified mortality rates of large carnivorous mammals or reported data that we could use to calculate these rates ourselves.

We focused on large terrestrial carnivores weighing 15 kg or more. We also looked for studies on mortality rates of four smaller species (coyote, wolverine, fossa (a cat-like predator found in Madagascar), and Tasmanian devil), as they are all considered top predators in some regions and ecosystems.

We found mortality rate estimates for only 17 (55%) of the 31 carnivore species included in our study. The studies were conducted in 27 countries on five continents.

Carnivores hunt in different ways

We found that mortality rates differ between carnivores with different social structures and hunting strategies.

Social predators, such as wolves and lions, tend to kill fewer animals per carnivore than solitary hunters such as bears, tigers, and Eurasian lynx. For example, on average, gray wolves kill one animal every 27 days per wolf, compared to every four days for Eurasian lynx.

Larger wolf packs can take down larger animals like bison more easily. Similarly, cheetah groups can take on larger prey than solitary cheetahs. This means they may not need to hunt as often.

Working in teams can also reduce scavenger losses, as groups can better defend their prey due to their numbers. They may also be better at scavenging and stealing each other’s prey (“kleptoparasitism”).

Canine predators such as wolves and wild dogs often use high-energy pursuits over long distances. For example, gray wolves can pursue prey for more than 20 km. In contrast, felines use stealth and an ambush hunting strategy. This saves energy.

Large solitary carnivores such as tigers, leopards and Eurasian lynx, which primarily hunt hoofed mammals, have similar mortality rates regardless of their body mass. This suggests that large terrestrial carnivores are forced to hunt prey that is closer to their size or larger, to compensate for the energy expended during hunting.

Small carnivores such as cheetahs, pumas and wild dogs often kill more prey than their larger counterparts, but consume only about half of what they kill.

This behavior benefits other species such as lions, bears, and wolves and is likely a consequence of the need to compensate for food theft and loss. It is estimated that pumas provide more than 1.5 million kilograms of carrion per day in North and South America.

If you’ve seen the movie The Lion King, you might think that hyenas steal and scavenge for food. But that’s not the case. Lions often steal from hyenas, as well as other carnivores like cheetahs and wild dogs.

Bias in mortality rate research

More than half (55%) of the mortality rate studies were conducted in North America. Africa follows with almost a quarter (24%), then Europe (12.5%).

Asia lags far behind with 7% of all mortality rate studies. This represents only 13 studies covering six species. This is despite being the largest continent, home to 17 (55%) of the 31 large carnivore species included in our study.

No reliable studies on mortality rates have been published in Australia.

A third (33%) of mortality rate studies focused on gray wolves, followed by pumas (20%), lions (12%) and Eurasian lynx (8%). This means that we know little about the predatory behavior and roles of other large carnivores.

Gray wolves are considered a threat to livestock and wildlife, a threat that humans value. This has prompted significant investment in research to understand their predatory behavior and that of other large carnivores in North America.

This work was then used to inform appropriate management and conservation of these predators and their prey.

Carnivores bring benefits

Mortality studies go beyond simply counting carnivore behavior. They provide deeper insight into predator-prey relationships and their effects on ecosystems.

Large carnivores shape ecosystems by scaring and killing their prey, which can alter their behavior, distribution, and abundance. They also provide food for other species, affecting the flow of nutrients and energy.

Large carnivores are also useful to humans in many ways. They can reduce the risk of vehicle collisions by killing deer that might otherwise wander onto roads. They can limit the spread of disease by preying on sick animals, and they control herbivores, helping livestock producers.

Yet carnivores, including Australia’s dingo, are still widely persecuted. We must do everything we can to preserve their pride of place at the top of the planet’s ecosystems.

Of course, if you really want to know which species is the deadliest, it’s humans. We are the dominant predator on Earth.

This article is republished from The Conversation under a Creative Commons license. Read the original article.