The secret's in the scat.
Cougars are great gardeners. You won’t see them carefully pruning bonsai trees with their claws or paging through a Burpee seed catalog, but scientists say that one of these bigs cats can plant around 94,000 seeds in a year. They do this by doing what cats seem to do best: eating and pooping.
Ecologists have been saying since the 1960s that apex predators—the carnivores at the top of their local food chain—keep the world green by killing and eating plant-eaters and keeping them in check, allowing plants to flourish. New research on cougars, though, suggests that some carnivores keep the world green in another, more direct way, by spreading the seeds they ingest when they eat their herbivore prey.
Cougars and other cats have a need for protein that restricts them to a diet that’s primarily meat, gaining them the badass term “hypercarnivore.” Obviously, they don’t set out to eat plants, but they do wind up consuming a lot of seeds when they eat other animals that do.
Biologist José Hernán Sarasola has seen this first hand. He and his research team spent months collecting and picking through cougar scats in Argentina’s Parque Luro Natural Reserve, where the cats’ diet is mainly made up of eared doves. In just 123 scats, they found nearly 32,000 seeds from different plants that the doves feed on, the bulk of which came from three grasses. When they planted some of these seeds, they sprouted just fine, and passage through the cougars’ guts doesn’t seem to hurt them.
Given the density of cougars in the reserve (nine animals per 100 square kilometers, or 39 square miles), the researchers estimate that the cats could spread about 5,000 seeds from just those three common plants per square kilometer every year.
That’s a lot of seeding, and the researchers say it shows that big cats and other predators are doing an important and overlooked job. By spreading that many seeds around, cougars help plants colonize new and unoccupied areas, and keep genes flowing back and forth between populations.
These effects likely aren’t confined to Parque Luro, either. The cougar’s range extends from British Columbia down to the southern tip of Chile, and it’s the most widespread mammal in the Western Hemisphere. Elsewhere in the world, seed-eating birds are found in most ecosystems, the researchers say, and overlap with big cats in many of them, so wild felines may be greening things all over the planet.
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