The delicate balance of life on Ecuador’s Galapagos Islands-whose unique, isolated ecosystem helped inspire Charles Darwin’s theory of evolution-is at serious risk. Mass tourism, invasive species, and ineffective enforcement of environmental regulations are the major threats facing these iconic islands, according to a UNESCO fact-finding mission.

Located 620 miles off the Pacific coast of Ecuador, the volcanic archipelago is famous for its wide array of wildlife, including giant tortoises, marine iguanas, flightless cormorants, blue-footed boobies, and the 13 species of finch that so fascinated Darwin. UNESCO recognized its historical and environmental significance 30 years ago when the islands became the planet’s first World Heritage site.

Tourism to the islands has tripled in the past 15 years, from 40,000 visitors in 1991 to 120,000 in 2006. The resident population has boomed correspondingly, putting a strain on the islands’ already fragile resources. Migrants come from the mainland in search of higher-paid jobs in the tourism and fishing industries. Clashes between these workers, whose livelihoods often depend on illegal fishing practices, and Galapagos National Park officials highlight the difficulties confronting the Ecuadorian government in implementing sustainable conservation programs.

Environmentalists also warn that the arrival of foreign plants and animals may severely disrupt the local ecosystem. The World Conservation Union Red List of Threatened Species states that at least 490 species of insects and 53 species of other invertebrates have been introduced to the islands, deliberately or accidentally. In addition, there are now more non-native species of plants than there are native ones; 60 percent of the islands’ endemic plant species are considered threatened.

Ecuadorian President Rafael Correa stated that possible actions to combat these threats include limiting new tourism and residency permits and restricting flights to the islands.