The world’s majestic “apex predators” are among the most prolific hunters on Earth. So which ones kill the most? Our new research shows that solitary hunters, such as bears, tigers and Eurasian lynxes, have higher individual kill rates than social predators, such as wolves and lions. Smaller species, such as cheetahs and pumas, tend to kill relatively more prey because their kills are often stolen by more dominant predators.
This type of information can help us better understand how different predators impact the environment. It can also help manage hunting quotas and assess human impacts on carnivores. These top predators play vital roles in ecosystems, but they are also among the most endangered animals in the world. Carnivores are often in conflict with humans, especially over livestock and public safety.
Our approach
Our study was the world’s first systematic review of the literature on predatory behavior of large terrestrial carnivores. Specifically, we examined the “kill rate” of carnivores—the amount of prey killed in a given period of time. We did this to better understand foraging and its effects on prey populations and ecosystems.
We reviewed 196 articles that measured large mammal mortality rates or provided data that we could use to calculate our own rates.
We focused on large terrestrial predators weighing 15 kg and above. We also looked for studies on mortality rates for four smaller species—the jackal, the wolverine, the fossa (a cat-like predator found in Madagascar), and the Tasmanian devil—because they are all considered top predators in specific regions and ecosystems. We found mortality estimates for only 17 of the 31 carnivore species included in our review (55 percent). The studies came from 27 countries across five continents.
Predators hunt in different ways
We found that kill rates vary among 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 lynxes. For example, on average, gray wolves killed one wolf every 27 days, compared to one every four days for Eurasian lynxes.
Larger wolf packs can more easily kill larger animals, such as bison. Similarly, groups of cheetahs can take on larger prey than single cheetahs. This may mean they don’t need to hunt as often.
Teamwork can also reduce scavengers’ losses, because groups can better defend their kills because they are more numerous, or they can be better at seeking out and stealing from others (“kleptoparasitism”).
Canine carnivores, such as wolves and African wild dogs, often rely on high-energy chases over long distances. For example, gray wolves can chase prey for over 20 km. In contrast, cats rely on stealth, using an ambush hunting strategy. It saves energy.
Single large carnivores, such as tigers, leopards, and Eurasian lynxes, which prey mostly on ungulates, have similar kill rates regardless of body mass, suggesting that large terrestrial carnivores had to hunt prey that were similar in size or larger to compensate for the energy expended in hunting.
Smaller carnivores, such as cheetahs, pumas, and African wild dogs, typically 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 result of a need to compensate for food theft and loss. Pumas are estimated to scavenge more than 1.5 million kilograms of carcass per day in North and South America.
If you’ve seen the movie The Lion King, you’d be forgiven for thinking that hyenas mostly steal and collect food from them. But that’s not the case. Lions often prey on hyenas, as well as other carnivores like cheetahs and African wild dogs.
Bias in homicide rate studies
More than half of the homicide studies (55 per cent) were conducted in North America. Africa is next at almost a quarter (24 per cent), followed by Europe (12.5 per cent). Asia is far behind at 7 per cent of all homicide studies. These are just 13 studies covering six species. This is despite being the largest continent, home to 17 of the 31 large carnivore species included in our review (55 per cent). No reliable studies of homicide have been published in Australia.
One-third (33 percent) of all kill rate studies focused on grey wolves, followed by pumas (20 percent), lions (12 percent) and Eurasian lynxes (8 percent). This means we know very little about the predatory behaviour and roles of other large carnivores.
Gray wolves are viewed as a threat to livestock and wildlife that humans value. This has led to significant investment in research to understand their predatory behavior and that of other large North American carnivores. Such studies are then used to inform the management and conservation of these predators and their prey.
Hunters are useful
Studies of kill rates do more than just count carnivore behavior. They provide a deeper understanding of predator-prey relationships and their effects on ecosystems. Large carnivores shape ecosystems by scaring and killing their prey, which can change their behavior, distribution, and abundance. They also provide food for other species by affecting the flow of nutrients and energy.
Large carnivores also help humans in many ways. They can reduce the risk of vehicle collisions by killing deer that might otherwise cross the road, they can limit the spread of disease by hunting sick animals, and they can help keep herbivores under control by helping livestock producers.
But carnivores, including the Australian dingo, are still widely persecuted. We must do everything we can to preserve their place of honor at the top of the Earth’s ecosystems. Of course, if you want to know which species is the biggest killer, it’s humans. We are the dominant predators on Earth.
Source: Port Altele
