US agriculture stands to lose billions in free ecosystem services from the often-feared and rarely respected humble bat. According to a recent study in Science bats in North America provide the US agricultural industry at least $3.7 billion and up to a staggering $53 billion a year by eating mounds of potentially pesky insects. Yet these bats, and their economic services, are under threat by a perplexing disease known as white-nose syndrome (WNS) and to a lesser extent wind turbines.
According to co-author Gary McCracken, head of the Department of Ecology and Evolutionary Biology at the University of Tennessee, Knoxville, his study’s estimate is actually quite conservative.
One little brown bat (Myotis lucifugus) affected with WNS at Howe’s Cave, New York. Photo by: Al Hicks, New York Department of Conservation.
“These estimates include the reduced costs of pesticide applications that are not needed to suppress the insects consumed by bats. However, they do not include the downstream impacts of pesticides on humans, domestic and wild animals and our environment,” said McCracken. “Without bats, crop yields are affected. Pesticide applications go up. Even if our estimates were quartered, they clearly show how bats have enormous potential to influence the economics of agriculture and forestry.”
According to the study 150 big brown bats in Indian eat just under 1.3 million insects annually.
Yet US bats are facing unparalleled threats, especially white nose syndrome, a disease only identified in 2006. White nose syndrome causes hibernating bats to develop a whitish fungus on their faces and wings. Although it is still unclear why the disease is fatal, it appears to impact bat hibernation patterns, leading to starvation. The disease is potent: populations suffer 75 to 100 percent mortality rates. In five years time more than a million bats have already succumbed to the disease and researchers fear some regions will lose bats altogether.
Wind turbines are another bat killer although likely less severe overall than white nose syndrome. The researchers estimate that by 2020 wind turbines will have killed between 33,000 to 111,000 bats in the Central Appalachian Mountains of Maryland, Pennsylvania, Virginia, and West Virginia. Researchers don’t yet know why bats are attracted to wind turbines.
According to researchers action is needed now to save bats, and their ecosystem services, from extinction.
“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,” explains McCracken.
(03/05/2009) Half a million bats have succumbed to a mysterious fungal disease known as white-nose syndrome in two years. Found in seven states in the northeastern US, this syndrome has left biologists baffled since first discovered in 2006. While researchers are still trying to uncover the relationship of the syndrome to the bats, a recent study published in Frontiers in Ecology and the Environment e-View suggests a way to mitigate the syndrome devastating affect. Employing a mathematical simulation the researchers found that using localized heat sources on hibernating bats may preserve populations while a long-term solution is found.
(10/30/2008) Researchers have identified the fungus that may have been the culprit in mass dief-offs of bats in the northeastern United States during the winter of 2006-2007. The research is published in this week’s issue of Science.
(08/25/2008) Numerous studies have shown that migratory bats are undergoing large fatalities due to wind turbines. Far more bats die due to wind turbines than birds, though they generally receive less attention. Now, researchers writing in Current Biology believe they know why bats are more susceptible to wind turbine fatalities.