Fences, power lines, dams and highways are all obstacles that block species migration [GALLO/GETTY]

For the elephants that are returning to southern Angola, after herds were devastated during the country’s civil wars, the battle is far from over.

Old land mines, sown during the decades of conflict that ended in 2002, are threatening the lives and limbs not only of people, but also of the growing elephant populations that are crossing into Angola from northern Botswana on ancient migration routes that continue into Zambia. Mines are a particularly stark example of how humans interfere with migratory journeys that have linked breeding and feeding sites across the globe for millennia.

Up to 10,000 animal species are thought to migrate. Yet, increasingly, air, water and land routes are being destroyed by barriers, ranging from roads, fences, dams and power lines to unsustainable hunting or fishing practices, habitat degradation, pollution and climate change.

One example is the critically endangered Irrawaddy dolphin, found in the Bay of Bengal and Southeast Asia. Barriers to its migration range from entrapment in fishing nets to conditions caused by gold mining and dam building.

Likewise, someone strolling through Norway’s Fennoscandia region in the 1900s would have marvelled at the abundance of Lesser White-fronted Geese, which then numbered in the thousands. Today, only 20-30 breeding pairs remain – the result, according to the World Wildlife Fund, of the drainage of wetlands in countries such as Greece, and of hunting along the bird’s migration routes.

In North America, one of the world’s fastest land animals, the Pronghorn antelope, faces obstacles such as highways and fencing. The harsh winter in 2010 left herds stranded and hungry, blocked by fences while they burned up their fat reserves searching for ways through. Similarly, in South Africa, 12 per cent of Blue Cranes, South Africa’s national bird, and 30 per cent of Ludwig’s bustards are dying annually in collisions with a growing number of power lines.

Climate change is also having a severe impact on the world’s most peripatetic animals. Migratory species, from Monarch butterflies to humpback whales, are suffering as a result of shifts in temperature and the disruption of the traditional timing, abundance and location of food sources.

The trend looks bad. But some countries are taking action. Since the Convention on the Conservation of Migratory Species of Wild Animals entered into force in 1983, its membership has grown steadily to include 116 countries in Africa, Central and South America, Asia, Europe and Oceania. To date, the CMS has concluded agreements and memoranda of understanding to conserve more than 26 migratory species.

Economic considerations of conservation

Thanks to the CMS, Papua New Guinea and Mozambique, for example, recently agreed on cooperative arrangements to conserve migratory dugongs, animals once thought by seafarers to be mermaids. Likewise, a 20-year agreement has recently helped to increase the number of harbour seals in the Wadden Sea, shared by Germany and the Netherlands.

Even butterflies’ migratory routes are being impacted because of climate change [GALLO/GETTY]

Protecting migratory species benefits not only the animals concerned, but humans as well. A ten-year program to restore and conserve seven million hectares of wetlands in China, Iran, Kazakhstan and Russia has improved conditions for the critically endangered Siberian crane, as well as drinking-water supplies, inland fisheries and carbon storage.

Austin, Texas, is home to the world’s largest urban colony of migratory bats, which live underneath the city’s central Congress Avenue Bridge. On summer nights, hundreds of people visit to witness the bats emerge for their nightly feed. Not only do the bats act as natural pest controllers, consuming up to 4,000 mosquitoes each per night; they also underpin a local tourism industry that generates an estimated $10 million a year.

On November 20-25, the CMS will hold its tenth Meeting of the Conference of the Parties in Bergen, Norway. Among other success stories, the participants can cite the example of the tiny Pacific island nation of Palau. Many shark species are now at high risk, owing to growing consumption of their fins, which are widely believed to boost sexual potency and enhance general health. But Palau is helping to reverse this trend.

Two years ago, Palau became the first country to declare its coastal waters a shark sanctuary – scientists estimate that shark-diving tours now generate around eight per cent of the country’s GDP, and that a single shark generates revenues from ecotourism amounting to €1.9 million ($2.6 million) over its lifetime.

Nature should never be prized merely for its economic value. But, in a world of competing demands and limited resources, economic considerations can help to tip decisions in favour of conservation rather than degradation. This kind of strategic thinking can help to ensure that the world’s 10,000 migratory species continue their journeys, so that future generations can also marvel at these nomads of the natural world.

Achim Steiner is United Nations Under-Secretary-General and Executive Director of the UN Environment Program.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial policy.

A version of this article was first published on Project Syndicate.

