Why Pleistocene Rewilding is a Bad Idea
In the modern world, many animals have either become extinct or endangered because of human impacts. Whether those impacts be overhunting, habitat destruction, or otherwise, mankind has proven itself to be a ravenous destructor. As a result, many parts of the world, such as a large chunk of Eurasia, have lost their species. For instance, Central Asia has lost its tiger population and lions have gone extinct in the Middle East.
But at the same time, mankind has also proven to be a healer of landscapes. Especially through the practice we call rewilding. The act of reintroducing certain species to repair ecosystems and restore the food webs. These include the Yellowstone wolf reintroduction, the rewilding projects in Argentina, Rewilding Europe, reintroduction efforts in the African country of Malawi, and the reintroduction efforts for tigers in the country of Kazakhstan. But some have thought of taking rewilding a step further, by introducing animals like lions, tigers, elephants, etc into North America for example, no longer killing exotic ungulates in places like Australia.
This is what is known as Pleistocene Rewilding. The idea of introducing exotic species to replace animals that went extinct at the end of the last ice age is to improve ecosystem health by filling the vacant niches left behind.
But is Pleistocene Rewilding actually a good idea? Or are those into it really distanced from real-world wildlife conservation? The answer looks to be the latter. And there are 4 reasons why.
1. Different Herbivore Behaviors: You will often hear from these people that many introduced herbivores have replaced certain extinct megafauna, and the same will happen if you do the same in other scenarios, like if you introduced African Savanna Elephants into North America to replace Columbian Mammoths for example. What isn't considered is that even if this is true, these animals will likely to things to ecosystems that the animals they're supposedly replacing didn't do. Let's look at a few examples.
It's said that the hippos in Columbia have replaced a giant camelid from the late Pleistocene. However, when these hippos deposit their fecal matter into the waterways, they create algae blooms. Something a giant camelid wouldn't have done (which I can also say from experience as I've handled alpacas). Hippos are also much more aggressive than a giant camelid would've been, and for all we know, probably negatively affect Amazonian manatees in the region.
Sambar Deer in Australia are said to have replaced the giant short-faced kangaroos in the genus Procoptodon. However, during the rut, stags will rub their antlers on trees to get rid of the velvet and Australian trees haven’t evolved to deal with this and are thsu damaged by it. Obviously, this isn’t something a giant kangaroo would’ve done. In this case it probably would’ve bitten off branches.
Well, you get the idea.
2. Unknown Predators: Those within the pleistocene rewildling community are also fond of the idea of introducing exotic predators into foreign ecosystems to replace pleistocene predators. Ideas from this community I’ve heard myself include putting cheetahs into North America to replace Miracinonyx cats, introducing lions into North America to replace the American Lion, and even introducing tigers into the Southestern USA and parts of South America to replace Xenosmilus.
But obviously, there’s a huge problem with this line of thinking: the naive prey animals and native predators.
The large herbivores will not know how to deal with exotic predators since they didn’t co-evolve with them, and this is the reason Bumese Pythons are such a terrible invasive species. And this would especially be the case when it comes to lions since their hunting tactics would be pretty alien to the native herbivores.
Not only that, but native predators would also be hit hard. They would be seen as competition by the exotic predators and would be killed out of territorial instinct, and likely displaced by them as well. Even the mighty grizzly would be vulnerable to the lion prides.
And before someone says they’d coexist like in the past with sabertooths and american lions, here’s what you need to remember: That was thousands of years ago, native predators will not suddenly remember how to live with cats similar to the ice age behemoths.
3. Lack of Tolerance: The majority of people would not approve of these plans, especially if they’d have to live with these animals. Even if you made the process more inclusive, or tried to anyway, it’s really doubtful they’d be on board with it because a lot of people are aware of invasive species and the impacts they have. Not only that, but many will find it dumb that so much time, money, and effort would be put into introducing foreign species to places, especially when those same resources could be spent on preserving native fauna.
4. Ecologically Unnecessary: Yes, when the ice age megafauna died out, the landscapes changed. But so did the fauna composition, and with edited fauna compositions if you will, new balances were created. In South America, the jaguar is now the top predator, and it along with the other predators keep the herbivores in line and the herbivores themselves have their own niches which help maintain the new landscapes. In Australia, the dingo became the apex predator in most of the continent and keeps the herbivores there in line, and they have their own niches that maintain the new landscape.
Basically, ecosystems change, they evolve with time. As a famous fictional character would put it, life found a way.
I bring this up because you’ll hear proponents of Pleistocene rewilding will tell you that the landscapes haven’t fully recovered from the end Pleistocene mass extinction. I’m not sure how they came to this conclusion, but I think the above examples disprove this. So not only would Pleistocene rewilding be ecologically damaging, but also ecologically unnecessary.
And now to quote the same fictional character.
“...
your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should.”- Ian Malcolm, Jurassic Park (1993).
