EnglishBy Jason G. Goldman
This is the third article in a three-part series on connectivity. Click here to read part one: “Coexistence, Not Corrals” and click here to read part two: “Building Bridges – Literally.”
Once upon a time, an animal that was sufficiently motivated could safely travel the 2500 miles from the forests of southern Mexico through Central America to wind up safely in Colombia. The so-called Mesoamerican land corridor is still used by animals that take to the skies, but those who are encumbered by Earth’s gravity must contend with an obstacle course of death just to go about their day. Wildlife-vehicle collisions on roadways are increasing throughout the world. Animals become electrocuted on power lines and battered by wind turbines. They are accidentally poisoned, burned, and drowned. They are intentionally poisoned, burned, and drowned.
One of the most damaging – but most invisible – threats they must overcome while navigating the hazards of daily life in the Anthropocene is the slow, steady deterioration of the habitats they rely on for food and shelter. As demand for pastures and cropland has grown, Central America has lost some eighty percent of its native vegetation. In the last twenty years alone, Nicaragua has lost more than 20 percent of its native forest cover. The forests that do remain have become fragmented, islands of habitat separated by wide swaths of city, suburb, and farmland.
Several years ago, researchers from Paso Pacífico, Northern Arizona University, and the University of Wisconsin wanted to understand how monkeys respond to the increasing conversion of the forests they and their ancestors have longed called home.
They discovered that the more fragmented, less protected forests in the Paso del Istmo region of Nicaragua hosted a more diverse primate population than did the Rio Escalante-Chococente Wildlife Refuge, which encompasses the largest remaining tropical dry forests in the country. Though the wildlife refuge supported more monkeys overall, they were mainly howler and capuchin monkeys, both classified as species of “least concern” by the IUCN.
It was only in the Paso del Istmo that any endangered black-handed spider monkeys were spotted – along with the howlers and capuchins. Conventional wisdom holds that spider monkeys require large, well-connected forests with a wide variety of fruit trees to survive. Their home ranges are quite large and they reproduce rather slowly, which ought to make them especially sensitive to habitat disturbance. Yet it turns out that even highly fragmented landscapes can still support populations of endangered monkeys.
It’s likely that at least some spider monkeys persist in the wildlife refuge where they are, apparently, harder to spot. Still, the lesson to take from the study is that our intuitions for conservation priorities would, at least in this instance, lead us astray. It might seem obvious at first glance that forest-reliant species would rapidly disappear along with forest cover, but the truth turns out to be quite a bit more complicated. Were conservationists to disregard fragmented areas simply because they were fragmented, it might be a net loss for conservation.
In Central America and elsewhere, landowners have been encouraged to cultivate trees as living fences in order to link larger swaths of forest elsewhere. Birds, bats, insects, and monkeys have all been observed using these as habitats and as travel corridors. In parts of Nicaragua where landowners have already begun implementing living fence rows, farmers report seeing spider monkeys and howler monkeys using them, alongside squirrels, sloths, iguanas, and a wide range of birds and insects.
The same principles apply even if you live in a city or suburb thousands of miles from the nearest monkey. Backyards benefit just as much from trees as do farms and ranches. Trees don’t simply offer habitats to urban-adapted critters; they create habitat complexity, making a space for species to move vertically as well as horizontally, or to hopscotch from yard to yard. The impacts are cumulative. According to a study conducted in Illinois, streets with multiple wildlife-friendly yards hosted nearly twice as many types of birds as those with fewer.
The ongoing loss of natural vegetation heralds a wide array of consequences for climate and biodiversity, but the truth is that many wildlife species are tenacious and can find a way to survive – and sometimes, even thrive – within a human-dominated landscape. And if wild animals can find a way to get by even while we convert their forests into farms and ranches, shouldn’t we do our part to make life at least a little bit easier for them?