The news that scientists plan to bring woolly mammoths back to the arctic tundra, by fusing the DNA of Asian elephants with that of their extinct ancestors, has raised some eyebrows in the world of conservation science.
However, the basic idea of reintroducing large mammals into a vulnerable ecosystem in order to restore and rebalance habitats depleted by our own destructive habits is now widely accepted.
When we remove large, influential creatures from an ecosystem, we create an imbalance that allows populations of other species to increase rapidly. For example, because bears, wolves and lynx are long extinct in Britain, the numbers of native red and roe deer and non-native muntjac have skyrocketed. This creates soil erosion and damage to forests and scrub, affecting rare and specialized species such as the nightingale and reducing the growth of new trees.
In extreme cases, the effects of losing a single keystone species can be disastrous. As Raquel Filgueiras of Rewilding Europe explains, when they disappear, other species are simply not able to take over their role. As a result, she says, “ecosystems then degrade, and sometimes completely collapse.”
The reverse is also true. When we put these keystone species back into a broken ecosystem, we begin to restore the balance between predator and prey and change the composition of the local flora. Although reintroducing cash is not a magic wand that can solve all problems, it can certainly help reverse losses.
Perhaps the best-known example is the reintroduction of wolves to Yellowstone National Park in the United States after an absence of nearly 70 years. The idea was that the wolves would keep the elk population under control, preventing overgrazing. Ultimately, this would recreate a more diverse and complex habitat, in what scientists call a “trophic cascade”.
The plan was extremely controversial at first, but 25 years later it has clearly worked, with Yellowstone having a much richer and better balanced ecosystem than before. Income from wildlife tourism more than covered program costs.
On a smaller scale, the presence of predatory birds such as goshawks, white-tailed eagles, and golden eagles has a similar beneficial effect by reducing the number of mid-sized predators.
Benedict Macdonald, the author of the book Rebirding, has long championed projects to restore lost or returning British wild creatures. In his forthcoming book, Cornerstones, which examines the impact of keystone species, he outlines the benefits of bringing one of our most charismatic raptors back to the New Forest.
“Goshawks feed on medium-sized predators such as magpies, jays and crows, which attack songbird nests for eggs and chicks. Reducing their numbers allows these little birds to thrive. Beneficiaries include red-listed species such as goldfinches, common thrushes and spotted flycatchers, which currently need all the help they can get.
Perhaps the most well-known keystone species is neither a predator nor a huge herbivore, but a rodent. Beavers – aptly known as “nature’s architects” – can transform a wetland ecosystem in a remarkably short time by damming a stream or river, adding layers of complexity. This allows a huge range of species – including kingfishers, willow tits, otters, water voles, damselflies and dragonflies – to thrive.
However, there is always opposition to these reintroductions, especially from farmers and landowners. The wolves argument may not be so surprising, but even beavers have proven controversial: some farmers claim that dams cause flooding in their fields.
And while it’s a great idea, it’s impossible to know at this time exactly what impact the reintroduction of mammoths to the Siberian steppes would have. Would it have the dramatic restorative effect the project hopes for? It will be very interesting to find out.
