What's all the fuss about rewilding?

Plus this weeks links to conservation news and job listings.

Hi it’s Ben and Charlotte, welcome to The Entmoot.

In this week’s issue we'll look at:

• What is the recent craze around rewilding?

• Canada’s carbon tax facing the axe

• Bird flu outbreak killing captive big cats in Vietnam

• And more…

Best links

Wildlife Conservation

• 15 pine martens released in Devon for reintroduction efforts (BBC)

• Stray dogs and cats affecting native carnivore numbers in Madagascar (Mongabay)

Climate Change

• Will carbon capture help the U.K? (BBC)

• Canada’s carbon tax is popular but now faces the axe (Guardian)

Zoo news

• Zoo may have to quarantine endangered crayfish (BBC)

• Bird flu outbreak kills many big cats in Vietnam (Guardian)

Jobs

• Zoo keeper positions are available at Exmoor Zoo, New Forest Wildlife Park and London Zoo (Wild Professionals)

• Find the latest environmental, Ecology, and fundraising positions here (Environmental jobs)

Featured Article

What is rewilding?

I’m sure it’s a phrase we have all heard in recent years, but what actually is rewilding? Isn’t that what wildlife conservation is already? And why is it any different to what we have been doing for decades?

Well, put into simple terms, rewilding is the process of restoring an area of land or sea to its state prior to human disturbance, usually by means of species reintroduction. When an ecosystem is balanced, nature can work to repair degraded landscapes to a healthy state and biodiversity can increase.

Rewilding takes a holistic approach to ecosystem health, rather than simply looking at individual elements - increasing the population of just one species is not going to be effective long-term if the habitat they exist within cannot sustain said species.

How does it work?

Fundamentally, rewilding aims to remove the impact of human activity and replace it with ecological processes that allow ecosystems to flourish, with the aim of them becoming self-sustaining.

An example of this in the UK is the potential for bison and wild boar to be vital ecosystem engineers within our woodlands.

The ability of these large and powerful herbivores to create clearings amongst trees can be highly beneficial, as gaps amongst the canopy allow light to reach the ground where a shrub layer can grow and thus create habitat for species such as the hazel dormouse. This diversification in habitat is also beneficial for native flowers, invertebrates, birds and bats, and so the process undertaken by the bison and boar provide vital ecosystem management that would not have occurred had they not been present. Fallen trees are also beneficial for fungi species, as some are known to grow only in decomposing wood.

Why is rewilding important?

The continual rapid development of towns, cities and transport networks has left many natural areas isolated and vulnerable. Not only has urbanisation resulted in habitat loss, but also the fragmentation of what habitat remains, resulting in species having a smaller range and a reduction in genetic diversity.

Rewilding looks to mitigate this disruption to natural spaces, while still allowing human development to take place. One solution is the introduction of ‘green bridges’ built across roads and railways, that allow wildlife to move between fragmented areas that would otherwise remain separated. This allows habitats to remain connected and still act as one larger and more diverse ecosystem rather than two that are weaker through being isolated from one another.

Rewilding also aims to protect natural spaces by identifying disruptions in ecological processes and trying to correct them.

A case study of success - Yellowstone

Perhaps the most famous example of this can be seen through the wolves of Yellowstone. In the 1920s, government policy allowed the wolves of the famous North American national park to be hunted to extinction. This led to a trophic cascade whereby elk were allowed to have a population boom without predators to manage their numbers. This increase led to severe over-browsing of trees such as willow, aspen and cottonwood, plants that make up the diet of another keystone species - the beaver. Fewer beavers meant fewer dams, resulting in marsh habitats becoming streams which meant greater levels of erosion, increased flooding risk and reductions in plant, fish, amphibian and invertebrate populations.

All this damage stemmed from the removal of one apex predator, and overall biodiversity was reduced to a critical level following the disappearance of the Grey Wolf.

Thankfully, in 1995 the Grey Wolf was reintroduced to Yellowstone, and since then numbers of scavenger species such as bears, eagles and ravens - who rely on the kills of wolves - have increased in the area. Elk numbers have reduced to a sustainable level which has created space for the beaver population to bounce back, allowing them to support a plethora of other species with the habitat they create once more.

Overall biodiversity is much higher thanks to the presence of a predator serving to manage their prey species, keeping the ecosystem as a whole healthy. This is a great example of how identifying imbalances - often caused by people - and correcting them allows nature to heal itself.

Is there a downside to rewilding?

While there are many success stories in the world of rewilding, there have also been failures.

Oostvaardersplassen (OVP) is an area east of Amsterdam where a rewilding project took place in an attempt to naturally restore marshland habitat. A variety of non-native grazing species such as Red deer, Konik ponies, and Heck cattle were introduced as they had undergone very little selective breeding and were thought to be closely related to their wild ancestors, making them potentially ideal candidates for managing vegetation. Other species introduced included red fox, hares, marsh harriers, greylag geese, white egrets, white-tailed eagles, spoonbills and bitterns amongst others, all in the hopes of a thriving ecosystem that supported a great range of species.

However, following severe overgrazing on the small and enclosed habitat, the project was designated a failure and around 3,000 large herbivores had to be shot before they starved. Population numbers had grown far too large for the area to sustain, and the Heck cattle had become aggressive due to being part of a controversial breeding programme where they were cross-bred with Spanish fighting bulls to more closely resemble their ancestors.

Bird numbers were also falling during this time due to a reduction in viable nesting habitat, and in 2014 more than 90% of deaths were animals shot to avoid starvation.

What has this taught us?

Even though important lessons have been taken away, the catastrophic failure of OVP has knocked the reputation of rewilding as a viable solution to the biodiversity crisis. There are many welfare and ethical considerations to be made before undertaking any project with such potentially disastrous consequences.

In 2018, a committee ruled that the number of large herbivores for the space provided should have been around 1,500 rather than the 5,500 that were initially introduced. Although dramatic, this failure has led to better-informed decisions going forward, and today the area is much more well-managed. No animal has had to be shot for fear of starvation since, and bird populations are on the upswing again.

An important takeaway is the need to keep species numbers in check to avoid the impacts of overpopulation. As previously discussed, when given the correct conditions an ecosystem can naturally repair itself, but it doesn’t take much for nature to become imbalanced and for ecosystems to fall into disarray. We have a delicate balance to strike if we’re going to get it right.

Moving forwards

We know that destroying habitats and endangering species is having a devastating impact on the world and, as a result, our lives too. The need to protect and rebuild natural habitats for our own good has never been greater, and we need to see a big shift towards the promotion of natural restoration alongside our own continued development. It’s clear that when properly managed, rewilding projects have the potential to be a great hope for global ecosystem recovery.

But if we continue to follow our insatiable apatite for exponential growth with no regard for the natural world, then habitats as well as human beings will continue to suffer. We play a key part in making sure that rewilding is a success - as long as we develop at a sustainable rate and maintain species at levels that are beneficial for the food web as a whole, there is hope that we can live in a world where nature supports us the way we so desperately need it to if we are going to survive as a species.

Thank you for joining

If you have enjoyed this week’s newsletter, let me know in a comment or share so more people can get involved in the conservation conversation. Thanks for reading and see you again next week.