Tuesday, March 03, 2020

Rewilding and its limitations


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I have been thinking a lot about rewilding lately and it’s a very appealing notion, not the least because, like carbon offsets, it assuages some of our ecological guilt as we preside over one of the largest extinctions in the world’s history. Briefly, it involves returning some parts of the earth to a more natural state, either by simply quarantining them and allowing nature to take its course or by actively managing them through restoring and replanting degraded and derelict land and removing introduced species or, lastly, by reinserting species which occupied a particular niche in a former time.

There is little argument with the first two aspects and there have been some notable successes. For example, the reintroduction of wolves to Yellowstone National Park has reduced the number of deer and increased biodiversity. The return of beavers in Wales has shown that their dams reduce the likelihood of flooding, rather than the other way around, while the planting of “bee corridors” of wildflowers in Norway or even the planting of flowering plants on top of bus stops in Utrecht, is not only helping to protect bees and butterflies from extinction as their ranges change under conditions of climate change, but ensures the continued pollination of crops. Read also about the Welsh woman who has been conducting her own twenty year 'guerrilla' rewilding campaign in Cork against introduced Sitka pines.

Despite these successes, some aspects of rewilding are more problematic. For example, the setting aside of large areas for wild nature, limits the land available for agriculture, especially in regions of human expansion and where there is demand for more protein -rich food. The dispossession of small - holders from reserved lands may in fact be counter -productive in terms of conservation and retaining diversity. For instance, Jeff Nesbit writing in “This is the Way the World Ends,*” notes  that attempts to halt the expansion of the Sahara Desert by planting a “Green Wall” of 50 million trees failed dismally with two thirds of them dying within a few months, but when local farmers in Niger and Burkina Faso began planting trees in mosaic fashion on their holdings and digging deep wells near them to capture and store water as they had traditionally done, the encroaching desertification was slowed far more successfully.



However, the revival or reintroduction of large mammals especially carnivores is even more controversial. While the resurgence of wolves in Yellowstone has been beneficial in the USA, the recreation of forested lands in Croatia and other places in the EU (Linnell and Cretois (2018), has brought with it an expansion of wolf, bear and Eurasian lynx populations, which are now causing stock losses on farms, which was most likely the cause of their near extinction in the first place. The EU does at least pay farmers compensation for stock losses due to this cause. In Siberia there are currently attempts to introduce bison, musk ox and moose and other large mammals. Could it work? Maybe. Maybe not.





According to experts such as Nogués- Bravo, Simberloff, Rahbek and Sanders, as reported in Science Daily, we simply don’t know for certain what effects this will have and should proceed only with extreme caution. Confirmation comes from New Zealand where stoats and weasels the natural predators of rabbits on their home turf, were introduced to control plagues of introduced rabbits which were devastating farms. Unfortunately, the stoats and weasels developed a taste for much easier prey -New Zealand’s unique ground dwelling birds such as Kiwis, instead and almost completely wiped them out. It is only now after decades of sustained poisoning and trapping efforts, that the ground dwelling birds are starting to recover. 

This is particularly relevant in the local context where there are repeated calls to use DNA samples to revive species such as the Tasmanian tiger, which was last officially sighted in 1938. More recently there are also calls to introduce the mainland emu to replace the smaller Tasmanian emu which was last seen in 1840, not long after white settlement. Although admittedly native species, they have few local predators other than man and the landscape is now thoroughly modified.  In the case of the emu, its original niche has by now most likely been taken up by the expansion of other ground fowl or other introduced species such as Lyrebirds and livestock. One has only to see images of the piles of dead emus at farmers’ fences in Western Australia to understand the fierce competition for food and water and why farmers there are calling for another 'Rabbit - Proof Fence' to run the length of the State and to be known as the  State Barrier Fence to keep them out of pasture and water courses and why conservationists think this is a bad idea. 

Heroic though this kind of rewilding may be, with most of our other unique native wildlife already under threat from various causes – deforestation, fire, disease, land use modification and development, together with fragmentation of their breeding ranges and now climate change, I am not sure that that should be our most important priority. I am with Nogués- Bravo, Simberloff, Rahbek and Sanders here. It is more important to conserve the species we have at present, than to risk introducing or reintroducing others with unknown consequences. 

And what of the woolly mammoth? The woolly mammoth roamed at time when the earth was much colder than today and when humans were very few in number. It is unlikely now that it could survive in the limited range which could potentially support it today. In fact, earlier periods of climate change and the subsequent proliferation of other species and competitors including hunter - gatherer humans, were most likely the reasons for its demise, along with the megafauna of Australia.

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*Thomas Dunne Books, New York, 2018 (pp.64 – 69)
 

Linnell, J. D. C. & Cretois, B. 2018, Research for AGRI Committee–The revival of wolves and other large predators and its impact on farmers and their livelihood in rural regions of Europe, European Parliament, Policy Department for Structural and Cohesion Policies, Brussels


Cell Press. "Experts urge extreme caution on 'rewilding' to save wild places." ScienceDaily. ScienceDaily, 8 February 2016. .



  1. David Nogués-Bravo, Daniel Simberloff, Carsten Rahbek, Nathan James Sanders. Rewilding is the new Pandora’s box in conservation. Current Biology, 2016; 26 (3): R87 DOI: 10.1016/j.cub.2015.12.044
 





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