for National Geographic News
Predator-control programs are very effective at killing coyotes, but they do little to help the United States sheep farmers they are designed to protect, according to a new study.
Black bears, grizzly bears, mountain lions, bobcats, and wolves have been effectively removed from most U.S. farming areas, leaving coyotes as the top livestock predators.
To protect sheep from coyotes, U.S. federal, state, and local governmentsalong with private livestock associationshave killed about 80,000 coyotes a year in recent decades, according to the U.S. Department of Agriculture.
But these efforts have not prevented a dramatic decline in domestic sheep populationsand the sheep industryover the past 60 years, according to a report in the March issue of Conservation Biology.
The theory behind predator control is that reducing the number of carnivores will decrease livestock losses. But it's economic conditions that are pushing sheep numbers down, not predators, the new study says.
Kim Murray Bergera conservation scientist with the Bronx, New York-based Wildlife Conservation Society (WCS)authored the study.
She used historical data to establish that the most important factor in the number of sheep produced over time is the price of the animals' main food, hay. The study says that 56 percent of the variation, year to year, is attributable to this alone.
Farmhand wages and the prices farmers receive for their lambs account for another 21 percent of the variation, according to the analysis.
The amount of money spent to control predators contributes about 6 percent to changes in sheep numbers.
Peter Orwick is the executive director of the American Sheep Industry Association (ASI). He agrees that there are many factors that affect the profitability of sheep farming. But he sees predator losses as among the most important.
Citing a report published by the U.S. Department of Agriculture's National Agricultural Statistics Service, he said that "predator losses, even with the predator [control] programs, represent over 37 percent of the losses in the industry."
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