“It’s freezing and snowing in New York – we need global warming!” – Donald Trump
For many people, their image of the American West is either that of sunny beaches, blue skies and glamorous people; or dusty, sun-scorched desert landscapes with tumble weed rolling through an old-timey town. But what if the tumble weed were to role straight into an impenetrable concrete wall? The enormous pile of tumble weed collecting on both sides, would be the least of the problems.
Recently Donald Trump reassured his followers that the 800 mile wall he promised earlier in his presidential campaign, is still very much still on the agenda. Although much has been talked about the impact of keeping the “job-stealing, rapist” Mexicans out of the USA, nothing has been discussed on impact it could have on wildlife near the border. Does Trump care about the environment? Going by his comments on Climate Change, neither does he understand or care about it. However, a greater threat to biodiversity near the mexico-US border, may soon come into fruition.
These areas are delicate ecosystems, home to a large and diverse population of mammals, birds and plants. The border is a regular migration path for many animals and birds, yet very few people have been talking about what this giant concrete border would mean for wildlife.
Artificial borders can however be very dangerous for animals and plants, especially threatened ones. Not only can borders block the movement of wildlife, but they can destroy the surrounding habitats. By isolating and fragmenting the habitats, as well as blocking the connectivity animals use to move from one place to another, both can have serious implications.
For some species there are sizeable populations on both sides of the border, these species depend on movements between populations for maintaining genetic diversity, and for recolonising habitat where they’ve suffered local extinctions. During the Cold War large fences and walls were built in Germany to reduce human movement for East to West. When the wall was brought down scientists found localised extinctions of many species in Western Germany, bought about by increased agricultural and industrial activity. Also restricting the size of mating pools animals are made more susceptible to diseases. Human barriers too can also disrupt pollination and disturb watersheds and waterways, sometimes leading to floods, which can destroy habitats.
There is already a barrier between the US and Mexico which is permeable in places by some species. However, in other places there are impassable fences, designed only to stop vehicles. Although designed to allow passage of animals and humans, they are not as effective as they could be and certainly allow for much less freedom than having no border at all. These barriers with their large numbers of personnel and human encampments, as well as the noisy and bright all-terrain vehicles, helicopters and the general noises of human activity are unlikely to be approached by wildlife. This creates a further border to active passage. Trump’s wall, which has been said would be 10-20 metres of solid concrete, would mean a substantial increase in human activity: many more roads, heavy machinery, workers’ barracks and waste.
In the past borders have had unpredictable and often serious effect on local wildlife. Australia has the most experience of fences in recent history. The “Rabbit-proof Fence” in the west and the “Dingo Fence” in the East were both specifically designed to keep wildlife out. The Dingo Fence is 3,000 miles long and designed to keep dingoes out of the fertile south-east, to stop predation the millions of sheep of northern Queensland. It was effective in keeping dingoes out, but had the unforeseen problem of creating an over-population of kangaroos. Which impacted the sheep even more significantly, by increasing competition for the fertile grasses, and by keeping the dingoes out, the kangaroos only natural predator. The Rabbit-proof Fence created a different sort of problems for its builders. The fence which was 1,100 miles across the country’s west was again designed to keep out the invasive rabbit, off agricultural land. However, rabbits had crossed the border before it was finished rabbits had escaped into the agricultural areas it was meant to protect, necessitating a second and, later, a third fence.
Worldwide, human built barriers have had unpredictable impacts on the wildlife. Unlike today when most new constructions allow for the passage of wildlife, these historical barriers didn’t have the benefit of ecological impact surveys and assessments. Structure such as land bridges, tunnels and underpasses all allow for the successful passage of wildlife across man-made barriers. However, given that the purpose of Trump’s wall is to stop the movement of people across the border, it is unlikely to incorporate passing areas for animals.
Any large scale, human-proof wall is certain to have significant and unavoidable impacts on the environment. It is unlikely that much concern would be given towards the environmental impact of such a wall before construction. The only thing we, in the UK at least, can do is hope the wall is never built.
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