Colony of bats

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 US$10 million a year.

Among other success stories, one 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 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 8 percent of the country's GDP, and that a single shark generates revenues from ecotourism amounting to 1.9 million euro (US$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 favor 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. Copyright: Project Syndicate, 2011. www.project-syndicate.org. Shanghai Daily condensed the article.