The predators form an unusual coexistence in the central Chilean Andes

In the highlands of the central Chilean Andes, an ecosystem consisting of only a few animal species is providing researchers with new insights into how predators coexist in nature.

“The cougar and the culpeo fox are the only major predators in the Chilean Andean landscape,” said Professor Marcella Kelly, of the College of Natural Resources and Environment. “And there isn’t a huge range of prey species, partly because of the guanacos [closely related to llamas] typically no longer found in these areas due to overhunting. With such a simplified ecosystem, we thought we could really understand how two rival predators interact. “

Kelly worked with Christian Osorio, a doctoral student in the Department of Fish and Wildlife Conservation, and researchers at the Pontifical Catholic University of Chile to trace the locations and potential interactions between cougars and foxes in central Chile. They focused on three axes of interaction: spatial (where the animals are in the landscape), temporal (the times of specific activity on a given landscape) and dietary (what each species is eating).

To understand the interaction between cougars and foxes, the researchers deployed 50 shooting stations at two sites in central Chile, one in the Rio Los Cipreses National Reserve and another on private land where cattle and horses are raised. They also collected excrement samples at both locations to analyze cougar and fox diets.

The team’s findings, published in the journal Diversity, showed that while cougars and foxes significantly overlapped where they lived and how long they were active, there was little overlap in what they were eating, with the cougar’s diet consisting mainly of a large species of hare introduced by the Europe, while the culpeo foxes favored the smaller rabbits, rodents and seeds. The two species of predators can successfully share a landscape and hunt for food at the same night time because, in essence, they order from different menus.

“It is likely that the foxes have realized that when they try to hunt hares, they may have problems with cougars,” Osorio explained. “If they hunt smaller mammals, the pumas don’t care, but if the foxes start targeting larger prey, the pumas will react.”

How predatory species interact is a crucial question for ecologists seeking to understand the dynamics that inform the balances of ecosystems. And while the puma has been designated as a species of lesser concern, the animal’s populations are decreasing and continue to be monitored by conservationists.

“The slightest concern does not mean no concern,” Osorio noted. “We have laws in Chile that protect the species, but the data we have to make a conservation designation is very sparse. As we accumulate more consistent and reliable data, the puma can be reclassified as vulnerable or even endangered.”

The hares that make up about 70% of the biomass in the puma’s diet are a non-native species, introduced to the area by European settlers. With guanacos absent from the landscape, the puma had to adapt its diet to survive.

With some land managers and conservationists campaigning for the removal of introduced hare species as a way to restore the area’s native ecosystem, Kelly and Osorio note that it’s important to understand that cougars would be significantly impacted by a reduction in their primary food source.

Another concern, which the two are currently studying, is the interaction between wildlife and humans. The national reserve sees more and more visitors eager to witness big cats and foxes in their natural environment, while the sheep and cattle industries increasingly use remote land for raising livestock.

“Cougars occasionally kill livestock, which is a challenge we’re looking into right now,” said Kelly, an affiliate of Virginia Tech’s Fralin Life Sciences Institute. “The government would like to preserve the puma, but there are competing challenges as to what kind of threat they pose to livestock and what kind of threat the livestock or sheep farming poses to them.”

Understanding how two predatory species can coexist has the potential to provide conservationists and ecologists with better ideas on how humans and wildlife can share a landscape.