At one time a panther could prowl all the way from southern Mexico to Colombia.
That was before decades of deforestation, agricultural expansion, and urbanization throughout the seven countries that share the isthmus joining North and South America. That was before the cutting, dredging, and flooding that created the Panama Canal.
But a monkey out to travel from Mexico's southern Lacandona forest to Panama's southern Darien jungle may get his chance yet. Under a project helped by funding from the United States, Central American countries are joining to create a biological corridor that will give plant and animal species the room they need to survive.
"The Central American isthmus is one of the great land bridges with tremendous biological importance to the world," says Jan Laarman, a Guatemala-based natural resources economist working with regional governments and natural resources organizations on the corridor project. "But small patches of forest don't fulfill that land-bridge function. So the idea is to connect small islands of biodiversity to create bigger areas for the migratory routes the region's animals and plants have always had."
The biological corridor concept has gained favor around the world in recent years as biologists and environmentalists have sought ways to safeguard biodiversity - especially animal and plant species requiring large areas to survive - within a reality of increasingly fragmented natural areas.
But the concept may face its biggest test in Central America.
On one hand, biologists single out the thin ribbon of land as one of the richest regions in plant and animal life in the world. It's the region's role as a "land bridge" where animals and plants have migrated and evolved for ages that has made for that richness.
Central America is estimated to hold 8 percent of the world's biodiversity. It is estimated to be home to between 18,000 and 20,000 plant species; the United States, with almost 20 times the land area, claims about 22,000. Panama alone is home to 929 species of birds, more than found in the US and Canada combined.
About one-third of all North American migrating birds pass by the Central America "bridge," according to the Smithsonian Institution's Migratory Bird Center.
But rapid population growth and agricultural expansion have also left the isthmus's habitats among Earth's most threatened.
Central America's population is expected to double by 2030. Panama alone loses 125,000 acres of tropical forest a year. El Salvador, which has almost no virgin forest left, lists more than 150 vertebrate species on the verge of extinction.
Another problem is that while the region's countries have generally set aside important areas as reserves, more than half of the region's 461 protected areas are considered too small to play a significant role in protecting biodiversity.
And legal protection of even those areas is notoriously lacking. Only Costa Rica and Panama have actually declared reserves as protected by law. And in rural areas, many officials still promote the thinking that forests are best cut down and replaced by "productive" land.
"Ideas like preservation and biodiversity protection are still hard to promote," Mr. Laarman says. "The priority is still land for agriculture, so some government officials will say there's already too much land in parks and reserves."
To the rescue, then, come the region's government leaders - with help from the US. Last June, the leaders of the seven Central American countries formally approved the biological corridor project.
That decision followed a US commitment to put up $25 million over five years to help the project's administration, specialist training, and public education.
Any acquisition or renting of land will be largely the responsibility of individual governments.
Panama has already approved an $8.3 million program - funded largely by the World Bank - to be implemented over seven years. As in several countries, Panama's efforts will be focused on its Atlantic coast, where most of its best natural habitat remains.
"We have a lot of untouched or relatively untouched area, but the problem is that much of it is neither in reserves nor protected," says Marisol Dimas, a biologist in the protected-areas department of Panama's National Resources Institute. "Given that reality, we decided to focus our efforts on sustainable development."
Panama plans to encourage ecotourism projects, spearhead a reforestation program emphasizing the planting of native tree and plant species, and focus on working with indigenous populations that inhabit large swaths of Panama's Atlantic coast.
From Ms. Dimas's perspective, the corridor's success will depend in part on sustained availability of financing. "But it will hinge just as much on the education and involvement of local communities" that tend to view "preservation" and "environmentalism" with skepticism, she says.
That need for education is a common thread running through the corridor project. In rural Honduras, for example, a radio program has started to develop a dialogue with small farmers on land use and species preservation. And in Guatemala, a "small corridor" project designed to link a unique volcano mountainside habitat with a swamp at the volcano's base is starting with discussions among farmers who would be affected by the corridor.
Another emphasis is on teaching "greener" agriculture: banana plantations that avoid animal-killing pesticides, sustainable forestry, and shade-covered coffee plantations that preserve the natural tree canopy.
"Education takes time," says Laarman, which is one reason he sees the corridor project stretching well into the next century.
But maybe by then, if that monkey has a little patience, he'll be able to swing from Mexico to Colombia again.