April 1, 2011

Bat Deaths Could Cost US Billions Each Year

The deaths of insect-eating bats in North America could have serious economic impacts on the United States, costing the agriculture industry some as much as $53 billion a year, according to a new analysis by U.S. and South African researchers published in the journal Science.

A fungal disease called white nose syndrome, combined with a growing number of wind turbines, which can ensnare the bats, have killed off more than one million bats in North America since 2006.

The deaths eliminate a vital natural pesticide worth $3.7 to $53 billion per year to farmers, the researchers said.

"Without bats, crop yields are affected. Pesticide applications go up," said Gary McCracken, head of the Department of Ecology and Evolutionary Biology at the University of Tennessee, Knoxville, who co-authored the study.

"Even if our estimates were quartered, they clearly show how bats have enormous potential to influence the economics of agriculture and forestry."

The analysis was based on "published estimates of the value of pest suppression services provided by bats," the researchers said.

The costs range from between "$12 to $173/acre (with a most likely scenario of $74/acre) in a cotton-dominated agricultural landscape in south-central Texas," the researchers wrote.

Extrapolating those estimates across the entire United States, the researchers found that "the value of bats may be as low as $3.7 billion/year and as high as $53 billion/year," wrote McCracken and co-authors Justin Boyles of the University of Pretoria in South Africa, Paul Cryan of the U.S. Geological Survey and Thomas Kunz of Boston University.

The study found that more than a million bats have died in North America during the past five years due to fungal diseases.  Some estimates are that "by 2020, wind turbines will have killed 33,000 to 111,000 annually in the Mid-Atlantic Highlands alone."

"Not acting is not an option because the life histories of these flying, nocturnal mammals -- characterized by long generation times and low reproductive rates -- mean that population recovery is unlikely for decades or even centuries, if at all," said McCracken.

The findings are published in the April edition of the journal Science


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