Monday, March 25, 2013

Rebuilding Golden Lion Tamarin Populations

Photo: Smithsonian National Zoo
by Nick Cunningham

Last week, Duncan wrote about the Mata Atlantica, or Atlantic Forest, in Brazil. I wanted to follow up with a post on one of my favorite little critters in the Atlantic Forest, the Golden Lion Tamarin. The campaign to increase forest cover near Rio de Janeiro dovetailed with efforts to conserve the Golden Lion Tamarin, which was a small reminder of just how interconnected species are with their habitat.

The Atlantic Forest stretches up and down Brazil's southeastern coast. However, since 3/4 of Brazil's population lives in this area, including the enormous cities of Rio de Janeiro and Sao Paolo, an estimated 90% of the original forest has been degraded or destroyed. Indeed, people have been settling in the Atlantic Forest for centuries, and the steady toll of development has left the remaining forest cover in small fragments.

The fragmentation of forests present threats to many species even if the total forest cover seems sufficiently large. When we were doing research in Brazil, we visited the habitat of the Golden Lion Tamarin, a small charismatic species that resides in the state of Rio de Janeiro. The GLT is endangered because its habitat is being lost to deforestation, which in Brazil is often due to cattle ranching or agriculture (soy and sugarcane).

GLT's live among the trees, and depend on fruit for food. Like many animals, it covers a large amount of area relative to its size. Studies show that GLTs need habitats of about 100 hectares in order to thrive. However, the Atlantic Forest has been so fragmented, that an estimated 83% of the remaining forest cover is in fragments of only 50 hectares or less. Unlike animals that feed on vegetation instead of fruit, GLTs cannot adapt well when their habitat is degraded. As a result, GLT numbers steadily declined over the past several decades.

Due to a concerted effort by NGOs, National Zoos (including the Smithsonian National Zoo), and governments, GLT populations stabilized in the early 2000's. Now, there are high hopes of reversing the trend. And the obvious way to rebuild GLT populations is to restore the habitat. Since reforestation on a mass scale is a slow and expensive process, it can be more effective by targeting key areas to reforest. Creating "ecological corridors," - tracts of forest that connect two separate forest fragments - allows foresters to greatly expand forest habitat at low cost. GLTs could travel safely through a forest corridor to another fragment that had been previously disconnected.

While we were in Brazil, we visited a small NGO, the Associacao Mico-Leao-Dourado (AMLD, which translates to Golden Lion Tamarin Association), which is spearheading efforts to build ecological corridors to increase GLT habitat.

Our research team at AMLD in Rio de Janeiro (2012)
AMLD's approach was much different from the other forest restoration projects we visited. For example, timber companies doing reforestation were interested in restoring sheer volume - intensively replanting trees and using lots of pesticide in order to kill competing grasses and rapidly cover a large area. This would allow them to sell "sustainable" timber which fetches a higher price. The primary objective of AMLD, on the other hand, was to create habitats safe for the Golden Lion Tamarin. This required a different approach, one that seemed more ecologically sound, though it was a slower and more expensive process.

Learning about the Golden Lion Tamarin emphasized the multiple objectives of forest restoration, which sometimes gets lost. Not only are forests essential for carbon sequestration, and local benefits like erosion control and filtering water. But, forests are home to hundreds and thousands of species, and without intact habitats, these species cannot survive.

The campaign to rebuild GLT populations is ongoing. While we left Brazil with as many questions as answers, learning about the Golden Lion Tamarin was a particular highlight for me.

*update: I just wanted to thank all the people who helped us with our research: IBIO, Conservation International, The Nature Conservancy, Smithsonian National Zoo, and of course Associacao Mico-Leao-Dourado.

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