“Top Cat” Pumas contribute more carrion to the ecosystem than other carnivores

Pumas have the most extensive terrestrial range of any mammal in the Americas, stretching from the Canadian Rockies to Patagonia. A new study has revealed the web of life that these elusive cats support, demonstrating how they are linked to over 485 other species, ranging from eagles feasting on their carrion to elk impacted by their “fear effect.”

Researchers examined 162 papers published between 1950 and 2020 that investigated how pumas, also known as mountain lions or cougars, benefit ecosystems and other animals. They discovered that large cats supply 1.5 million kg of meat to scavenger populations spanning North and South America every day, with 281 species feeding on carcasses they have killed.

The paper, published in Mammal Review, also identified 203 species as puma prey; 40 that are affected by their fear of pumas; 12 that compete with pumas; and seven species that benefit from the ecosystem services they create.

“We went into this thinking pumas were connected to loads of other species for a variety of reasons,” says lead author Dr Laura LaBarge from the Max Planck Institute of Animal Behaviour. “But it was so surprising when we went through the enormous range of species connected to them, especially those that are indirectly affected by pumas, like invertebrates or plants.”

When pumas make a kill they act as “ecosystem engineers” because the carcass, or carrion, becomes a source of food for scavengers and decomposers. Pumas are apex carnivores (but not top carnivores) and research suggests they have adapted to allow for about a third of their food to be stolen by higher predators such as wolves and bears, meaning they are used to running off and leaving the leftovers for other wildlife.

One study found that pumas in Patagonia contributed three times more carrion to the ecosystem than grey wolves in Yellowstone national park, despite living at lower densities. Another paper looking at ecosystems in Greater Yellowstone found that 215 carrion beetles feed on carcasses caught by pumas. They also affect the distribution of condors in South America and early findings suggest they have an impact on bald and golden eagles in the Rocky Mountains.

Researchers found 40 species, including ungulates such as elk, white-tailed deer and vicuña, were impacted by the fear effect. Pumas are ambush hunters and tend to hunt from predictable areas, whereas wolves hunt prey over long distances. This means the fear effect – and therefore the areas ungulates avoid – is more pronounced with pumas than wolves, researchers believe.

“It’s just incredible how many domino effects you can have from these large carnivores which influence the distribution of foraging animals,” says senior author Dr Mark Elbroch, an ecologist from Panthera, the global wild cat conservation organisation. “You’ve got areas on the landscape that are safe, and areas that are risky for these hoofed animals to feed, and it’s just incredible all the things that changes – plant architecture, plant communities, birds, and even the soil chemistry.”

We cannot have these rich, dynamic ecosystems without these top predators. We have to protect them to protect wilderness
Christian Hunt, Defenders of Wildlife

Moreover, pumas also provide ecosystem services to seven species. In North Dakota the recolonisation of pumas is thought to have saved $1bn (£740m) in deer-vehicle collisions. Pumas also reduce the incidence of some diseases in prey animals: for example deer affected by chronic wasting disease are unlikely to be able to escape from an attacking puma.

Elbroch says: “Even as someone who has been studying pumas for a long time, it is still amazing to sit back and say ‘my goodness, look at how incredible this species is’ and see how interconnected it is in these ecosystems. But even to sit back for a little bit longer and say ‘wow, look at the complexity of life’, because it is truly amazing. All of these relationships are occurring all the time, all around us, so I just enjoyed the fact that this paper was a celebration of this species and a celebration of life.”

There is little published research on pumas from the tropics and subtropics, which account for a third of their range, and are among the most diverse ecosystems in the world. LaBarge believes the number of connections they found in this study probably “only scratches the surface” of pumas’ true impact.

Because of their elusive nature, puma populations are difficult to study. Their numbers declined drastically after European colonisation of the Americas but in the past 20 or 30 years there has been evidence of a small recovery, stabilising at about 50,000 breeding pumas globally. In South America there has never been a long-term study, but the International Union for Conservation of Nature believes numbers are declining.

Pumas are threatened by habitat loss and fragmentation, vehicle collisions and hunting by humans. Several isolated populations suffer from low genetic diversity with “severe health consequences”, according to the paper. Researchers hope the paper will highlight the benefits of puma conservation as a public good, showing the importance of creating integrated human-wildlife ecosystems.

Christian Hunt, an author of the study and representative of Defenders of Wildlife, says: “The main takeaway for me is that we simply cannot have these rich, dynamic ecosystems without these top predators. We have to protect them to protect wilderness.”

Hunt believes one of the greatest challenges is to change people’s perception of pumas as scary and reduce conflicts between humans and these big cats (which are generally terrified of people), with compensation schemes for farmers and better community outreach.

He says: “For us, the question is not whether pumas and people can coexist at this point. It’s a question of whether we, as an expanding society, have the grace to accommodate this animal and to leave it some room as we continue to encroach upon its habitats. I think ultimately, the puma’s future – like so many other large animals in the 21st century – is going to depend, really, on our ability to coexist and to make peace with the wild.”

Kate Vannelli, a big cat specialist at WWF, who was not involved in the research, says: “This study helps to highlight how there is an interdependence between people and big cats, and big cats are inextricably tied to their landscapes, as demonstrated by the huge amount of diverse biotic relationships highlighted in this study. This integration is extremely important to acknowledge if we want to conserve big cats.”

This article by Phoebe Weston was first published by The Guardian on 4 February 2022. Lead Image: Pumas contribute 1.5m kilograms of meat a day to scavenger communities across North and South America. Photograph: Panthera/Mark Elbroch.

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