By SIMON ROMERO
PUERTO AYORA, Galapagos Islands


THE MOUNDS OF reeking garbage on the edge of this settlement 960 kilometers off Ecuador’s Pacific coast are proof that one species is thriving on the fragile archipelago whose unique wildlife inspired Darwin’s theory of evolution: man.

Tiny gray finches, descendants of birds that were crucial to his thesis, flutter around the dump, which serves a growing town of Ecuadoreans who have moved here to work in the islands’ thriving tourism industry.

The burgeoning human population of the Galapagos, which doubled to about 30,000 in the last decade, has unnerved environmentalists. They point to evidence that the growth is already harming the ecosystem that allowed the islands’ more famous inhabitants - among them giant tortoises and boobies with brightly colored webbed feet - to evolve in isolation before mainlanders started colonizing the islands more than a century ago.

The growth has become enough of a threat to the environment that even the government, which still welcomes growth in the tourism industry, has expelled more than 1,000 poor Ecuador eans in the past year from a province that they feel is rightfully theirs, and it is in the process of expelling many more.

By limiting the population, officials hope to preserve the natural wonders that bolster one of Ecuador’s most profitable sectors: tourism. But the measures are feeding a backlash among unskilled migrants who say they are being punished while the country continues to enjoy the many millions of dollars tourists bring to Ecuador, one of South America’s poorest nations.

“We are being told that a tortoise for a rich foreigner to photograph is worth more than an Ecuadorean citizen, said Maria Mariana de Reina Bustos, 54, a migrant from Ambato in Ecuador’s central Andean valley, whose 22-year-old daughter, Olga, was recently rounded up by the police near the slum of La Cascada and put on a plane to the mainland.

The first settlers came to the islands to live off the land, working as fishermen, ranchers and farmers. Now, most of those who fly from Quito, the capital, or sneak on the islands in boats are lured by different sorts of riches: the relatively high wages they can earn as taxi drivers and hotel maids or workers in the islands’ growing bureaucracy.

For decades, the country’s leaders did little to prevent people from coming here, partly to build the tourism industry and then to ensure the government had a presence among the pioneers. There was something of a natural limit on growth: the country had put aside 97 percent of the archipelago as a park.

But as tourism and migration grew over the last decade, pressure began building within the scientific and environmental community to act on curbing the islands’ population. The United Nations put the Galapagos on its list of endangered heritage sites in 2007.

Scientists here said people had already done significant damage, pointing to fuel spills, the poaching of giant tortoises and sharks and the introduction of invasive species that threaten animals endemic to the Galapagos.

“With people come cats, and with cats come threats to other animals found nowhere else in the world,” said Fernando Ortiz, coordinator of the Galapagos program for Conservation International.

Technically, residency is granted to a limited number of people, including those born here and their spouses, people who arrived before 1998 and those with temporary work permits. The police, known in local slang as the “migra” for their role in tracking down illegal migrants, set up impromptu checkpoints throughout the islands. But the same government that oversees the expulsions also offers subsidies to people living on the islands.

One subsidy allows gasoline to cost about the same here as on the mainland. Another allows residents to fly between the islands or to Quito for a fraction of what foreigners pay. A black market in residency thrives in which migrants marry established residents to obtain coveted identity cards.

The result: Puerto Ayora’s streets beckon with discos, food stands and souvenir shops. On the outskirts, a billboard with the image of Leopoldo Bucheli, the pro-development mayor, celebrates a project called El Mirador that is clearing an area on the edge of town to build 1,000 new homes.

“All we want, like people anywhere on this planet, is a dignified existence,” said Yonny Mantuano, 36, who bought a lot to build a home at El Mirador. He heads the teachers union here, whose 600 members have chafed at one of the government’s new attempts to limit subsidies: a measure this year cutting their cost-of-living bonus.

The government’s somewhat haphazard view of life here is echoed by the people. Margarita Masaquiza, 45, an Indian from Ecuador’s highlands who arrived here at the age of 14, abhors the government’s expulsions.

“We built this province with our own hands, so, yes, it pains us to see our countrymen deported like animals,” Ms. Masaquiza said. “After all, we are indigenous Ecuadoreans, how can we be illegal in our own country?”

But when asked how she felt about the impact of new migrants on her four children and four grandchildren, Ms. Masaquiza adopted a different tone.

“We must preserve opportunities for our families,” she said.

PHOTOGRAPHS BY RUTH FREMSON/THE NEW YORK TIMES / Migrants from the mainland are putting pressure on the original residents of the Galápagos, like these blue-footed boobies.


Galápagos officials have been expelling illegal residents. A migrant in Puerto Ayora.


PHOTOGRAPHS BY RUTH FREMSON/THE NEW YORK TIMES / At Luis Mendoza’s home in Puerto Villamil hangs a carcass of wild pig he hunted to help feed his family.


Jobs in the tourism trade pay well. A sea lion on Tintorreas Island.