Yellowstone Rewilding Is Complex

The return of wolves to Yellowstone National Park is one of the greatest trophic rewilding stories. A new paper synthesises over 40 years of research to tell the scientific story.

Professor Mark Boyce’s key conclusion is that there was not one, but many trophic cascades, and that these trophic cascades happened in different places and at different times (spatial and temporal variability). During the summer for example, elk avoid wolves by climbing to higher, steeper habitat. Hunting also tends to takes place at dusk and dawn, to the extent that “elk appeared to ignore wolves during the day”. Such differences in space and time increase heterogeneity (things are distributed more patchily than uniformly).

These trophic cascades are further complicated by rebounding populations of grizzly bears, cougars and bison. Bears steal wolf kills, and are also specialised at taking elk calves. Cougars are subordinate predators to wolves, and their behaviour changes as the wolf population expands.

Boyce also believes that “the consensus will be that numerical declines in elk have contributed more to trophic cascade than has behavioural avoidance of wolves”, slightly challenging the Landscape of Fear theory. In other words, Yellowstone rewilding is more about wolves killing deer than scaring them.

Rewilding in Yellowstone would not have happened without the National Park Service’s policy of “ecological process management”, which actually minimises management and lets fires, floods, carnivores and herbivores lead the way. However, according to Boyce this policy under threat by political pressure to control the growing bison population.

Boyce is sceptical of concerns that “heavy grazing and browsing” by bison might “damage” vegetation:

“We do not know how bison will affect Yellowstone, but surely we will learn a great deal more if we allow the bison population to take its course rather than intervening in the fashion that will be arbitrary to the underlying ecological system. Whatever influence we can have as scientists, we must insist that the National Park Service maintain its policy of ecological process management for their Crown Jewell that is Yellowstone National Park.”


Wolves for Yellowstone: dynamics in time and space by Mark S Boyce was published in the Journal of Mammalogy on 10 October 2018 (Volume 99, Issue 5, Pages 1021–1031).

The Forgotten Habitats of Large Consumers

As populations of big beasts around the world recover, it turns out they live across a greater variety of habitats than we assumed, says this study.

Large-bodied consumers like alligators, wolves, otters and pumas are recovering from persecution. Where previously their populations were decimated, today they are recolonising their historic ranges.

And as they rebound, it turns out we don’t know as much about them as we thought.

The textbooks say that American alligators live in freshwater wetlands, but people keep finding them on the beach. Similar observations are being made for rebounding sea otters in California, which keep turning up in saltmarsh and seagrass meadows.

Image 2
Photo by James Nifong

Why did we assume they didn’t like these habitats? Probably because by the time we studied them, their numbers and habitats had already been decimated.

Other examples of large consumers recolonising ‘unusual’ places include:

  • Harp seals and black-backed jackals on the beach
  • Gray wolves and river otters on the coast
  • Mountain lions in grasslands
  • Orangutans in disturbed forest

This is important for historical baselines of predator diversity, as the authors explain:

“For example, for salt marshes we need to insert alligators, sea otters, coyotes, bobcats and river otters (and likely bears) into the higher trophic levels in the food webs.”

The good news it that if these large consumers are comfortable across a wider range of habitats, then their recovery might be easier than we thought. The flip side to this is that many of the habitats it turns out they need, might not be protected or considered in their recovery strategies.


Are the ghosts of nature’s past haunting ecology today? by Brian R. Silliman, Brent B. Hughes, Leo C. Gaskins, Qiang He, M. Tim Tinker, Andrew Read, James Nifong and Rick Stepp was published in Current Biology on 7 May 2018 (Volume 28, Issue 9, Pages R532–R537).

Online Cave Paintings

Humans have been drawing other animals for at least 45,000 years. We know it was one of the first things we did when we migrated into Europe and discovered its lions, bears and rhinos.

The paintings below are from the Chauvet Cave in southern France, and like others from across our planet, they show the regional megafauna – the local beasts.



Images: Bradshaw Foundation

There are plenty of theories for why we made these images. They might have been religiously important, they might have created “hunting magic”, they might have been menus, graffiti, and/or art.

Whatever the theories might be, tens of thousands of years later we are still obsessed with these images. Of all the things we choose to watch on our phones and computers, encounters with megafauna are one of the most popular. You might already be familiar with some of these:

With 8 million views, 15 million views, 35 million views – these sit in the YouTube hall of fame as some of our most watched moving images.

What’s fascinating about these particular videos – and what makes them even more similar to ancient cave paintings – is they are all faked. These replica beasts have been painted, not onto cave walls, but onto the frames of our shared videos.

Of course the video artists are influenced by the rewards of a viral video, as well as fame. Same for the people behind Nessie, Ogopogo, Yeti, Chupacabra and the countless “Phantom Cat” sightings.

But what about the millions upon millions of us glued to these encounters? We don’t watch these simulations for money or fame.

Is it ecological boredom? A psychological escape? Primal thrills?  The spell of the sensuous? A mixture of all these?

All we can know for sure, is that painted or real, these other animals continue to be part of us.



This article was originally published on Bald Ideas