July 2008

Good Fences Could Make Good Osprey Neighbors Out of Colombian Fish Farmers

By David Dudenhoefer

			En Español More About This Project Eco-Exchange Archive Eco-Index

Ospreys that nest in the United States and Canada must migrate thousands of miles to reach their wintering grounds in South and Central America. But for many of the birds, their winter sojourn ends tragically when they try to prey on tilapia, which are raised on thousands of fish farms across the region.

According to Colombian wildlife biologist César Márquez, fish farmers shoot about 2,000 ospreys per year in his country alone. Though this number represents a tiny fraction of the ospreys that fly to and from North America each year, the killings pose a threat to the species over time, especially since Colombia is one of several countries in South and Central American where fish farming is on the rise.

The osprey (Pandion haliaetus) -- an eagle-sized raptor with the voice of a songbird and a diet that consists almost exclusively of fish -- lives near lakes, rivers, and coastal areas all over the world. In the Western Hemisphere, ospreys breed everywhere from Alaska and Nova Scotia to northern California and Florida, and winter everywhere from the southern United States to Argentina. Though osprey numbers plummeted in the 1950s and '60s due to the effects of DDT and similar pesticides, they've been on the rebound since the early 1970s, when DDT use was prohibited in the United States.

While North America has a healthy osprey breeding population, the birds' situation grows precarious as they migrate south each winter. Tilapia farming is expanding across Latin America, where fish farmers don't hesitate to shoot predators that cut into their profits. According to Márquez, Colombia has between 2,000 and 3,000 fish farms that raise red tilapia for markets in Bogotá and other cities, and neighboring Ecuador and Brazil have comparable tilapia industries and osprey mortalities.

He is consequently working with fish farmers in his country to promote an alternative to shooting the birds. After testing various ways to discourage ospreys from preying on tilapia, Márquez settled on a technique of surrounding fishponds with chicken-wire fences and stringing colored wires over the water. Field tests have confirmed the method's effectiveness, and Márquez is now setting up demonstration sites, producing a manual on their construction, and organizing a campaign to convince fish farmers to build them.

The project, which is funded by the Neotropical Migratory Bird Conservation Act and supported in Colombia by the Alexander von Humboldt Institute, grew out of Márquez's lifelong fascination with birds of prey. An architect and urban planner by training, Márquez returned to graduate school to get a Masters degree in wildlife biology. Since then, he has dedicated himself to studying and educating people about birds of prey. He is the author of the book Diurnal Raptors of Colombia, and of a chapter in the book Raptors of Chile.

According to Marc Bechard, a raptor expert and professor at the Boise State University Department of Biology who has collaborated with Márquez regularly over the past decade, "César is one of a very few biologists who work to conserve raptors in Colombia, and he works diligently at it."

Colombia is an extremely important country for raptor conservation, given that it has the world's greatest bird diversity. Colombia has 77 raptor species -- nearly three times what is found in the United States and Canada. Many raptors that breed in North America winter in Colombia, and the country is the point of entry into South America for the bulk of the Western Hemisphere's migratory birds.

While Bechard lauds Márquez's work, he notes that this project won't be easy since every tilapia an osprey eats means less income for the farmer. He expects fish farmers to resist any change that might cut into their profits.

Márquez says farmers he has interviewed claim that ospreys steal about 30 percent of their fish, but he suspects they are exaggerating the birds' impact. Though it is illegal to kill an osprey in Colombia, the law isn't enforced so there is no real deterrence to shooting the birds. When talking to farmers, the wildlife biologist focuses on their bottom lines, offering them a more efficient way of protecting their fish. He notes that the fences also protect tilapia from predators such as night herons, which are common in fish-farming areas. His pitch to fish farmers is that they can improve their harvest significantly, and thus increase their income, by using bird barriers instead of shooting ospreys. "We want to show [the farmers] the costs and benefits of enclosing their ponds," says Márquez, adding that a fence and wires should protect a fishpond for about five years. "Of course, protecting the ospreys doesn't have a price."

It does, however, have a cost, and Bechard notes that it would be easier to get farmers to make the initial investment of installing the barriers if there were some sort of tax break or other incentive. The United States Fish and Wildlife Service has covered the cost of designing and testing the barrier and will finance building demonstration sites, creating training materials, and giving presentations, but there are currently no funds to help farmers purchase materials. Márquez is considering lobbying Colombian and regional authorities for fiscal incentives.

Though many of the farmers Márquez has spoken with have expressed interest in the barriers, he admits that installing them does not guarantee that farmers will stop killing birds. He laments the fact that on the farms where he tested different barrier designs, workers continued to shoot ospreys.

Márquez notes that farmers all over Latin America routinely shoot birds of prey on the pretext of protecting their chickens or small livestock. While the challenge of halting such behavior is daunting, the conservation payoff could be significant. And any success or lessons learned from the osprey project could be applied in other fish farming areas and might strengthen raptor conservation strategies in general.

Contacts: César Márquez, Instituto Alexander von Humboldt, Colombia. Tel: +571/287-7515, x 104, cmarquez@humboldt.org.co. Marc Bechard, Boise State University. Tel: +208/462-3530, mbechard@boisestate.edu.