Scat secrets: Edmonton study explores role of predator poop in spreading plant seeds

Some of the world's most ferocious predators — natural-born killers such as cougars and bears — are sort of gardeners in disguise, according to a new study from the University of Alberta.

Scientists study tongue twister called 'diploendozoochory' to get the dope on droppings

By eating seed-eating herbivores, predators like the cougar help plants spread across the forest floor. (Fotolia)

Some of the world's most ferocious predators — natural-born killers such as cougars and bears — are sort of gardeners in disguise, according to a new study from the University of Alberta.

The secret is in the scat.

The team of Edmonton scientists has been exploring the role of animal poop in the dispersal of plant seeds on the forest floor.

It turns out, seeds of all kinds are often spread and germinated by hitching a ride in the bowels of both prey and predator.

Plants and poop repopulation 

The process is called Diploendozoochory; sort of like nature's version of Russian dolls.

For instance: a bird eats a wild chokecherry, then gets devoured by a fox; the fox carries the bird inside his belly, which has the seed inside his belly. Eventually the seed is deposited in the form of scat, far from the tree it came from.

After the undignified journey, the seed grows into a new chokecherry tree, allowing the cycle to begin again. 

"It happens because plants can't move, and they need to get their young away from home, so to speak, so they have space to grow," said lead researcher Anni Hämäläinen. "So a lot of plants have solved this problem by getting animals to do it for them. 

"The predator, be it a fox or a bird or prey ... will move those seeds to far away locations that they would not have otherwise."

This coyote scat, riddled with seeds, goes to show just how good predators are at keeping nature green. (Supplied)
Instead of degrading the seeds, passing through the guts of multiple animals might actually allow them to flourish, said Hämäläinen.

"Thick-shelled seeds may benefit from the wear and tear of passing through the guts of two animals, making them better able to germinate than if they had passed through the gut of the prey alone," Hämäläinen said in a statement.

"It's even possible that some plants have evolved specifically to take advantage of these predator-specific behaviours."

The new Edmonton-based study comprehensively examined existing research on the phenomena to identify patterns and explore how the process alters plant populations and seed evolution. It was published in the journal Ecosphere on Thursday.

"It seems like it could be happening broadly in a lot of different systems, but it hasn't been studied systematically enough for us to know what the role of the predator is, in most cases.

"That is really why we ended up writing this paper." 

'Gaps in our understanding'

First described by Charles Darwin in 1859, this type of seed dispersal has only been studied a handful of times. But as climate change transforms natural landscapes, research in the field is becoming more critical, said Hämäläinen.

"Climate change will alter where some plants can find suitable places to grow. Seed-carrying predators may have a role in helping plants cover a larger area and hence move with the changing climate."

Habitat disturbance may also change the role predator poop plays in spreading seeds, said Hämäläinen.

Unlike prey animals, predators often cover longer distances. As habitats become more degraded by humans, animals at the top of the food chain may become the only species large enough to traverse some areas and help seeds take root.

"Our work has highlighted how interesting and important diploendozoochory is," she said. "And we hope that it will help and encourage others to fill some of these gaps in our understanding."

About the Author

Wallis Snowdon

Journalist

Wallis Snowdon is a digital journalist with CBC Edmonton. She has nearly a decade of experience reporting behind her. Originally from New Brunswick, her journalism career has taken her from Nova Scotia to Fort McMurray. Share your stories with Wallis at wallis.snowdon@cbc.ca