1, Disease and heedless management of windturbines are killing North America’s bats, with potentiallydevastating consequences for agriculture and human health.
2, We have yet to find a cure for thedisease known as white-nose syndrome,which has decimated populations ofhibernating, cave-dwelling bats in the Northeast. But we can reduce the turbinethreat significantly without dismantling them or shutting them down.
3, White-nose syndrome (also known asW.N.S.) was first documented in February 2006 in upstate New York, where itmay have been carried from Europe to a bat cave on an explorer’s hiking boot.In Europe, bats appear to be immune, likely the outcome of a longevolutionary process. But in North America, bats are highly susceptible to thecold-loving fungus that appears in winter on the muzzle and other body partsduring hibernation, irritating them awake at a time when there is no food. Theyend up burning precious stores of energy and starve to death.
4, The consequences have been catastrophic.A 2011 study of 42 sites across five Eastern states found that after2006 the populations of tri-colored and Indiana bats declined by more than 70percent, and little brown bats by more than 90 percent. The population of thenorthern long-eared bat, once common, has declined by an estimated 99percent and prompted a proposal from the United States Fish and WildlifeService to list it as an endangered species. Other species of hibernatingcave-dwelling bats have declined precipitously as well.
5, Whether these bats will recover or goextinct is unclear. Meanwhile, W.N.S.continues to spread rapidly. On the back ofthis year’s extremely cold winter,it moved into Michigan and Wisconsin. It isnow confirmed in 23 states and five Canadian provinces.
6, Tree-dwelling bats don’t seem to beaffected by W.N.S., since they don’t hibernate in caves. But wind farms arekilling them.
7, Wind turbines nationwide are estimatedto kill between 600,000 and 900,000 bats a year, according to a recentstudy in the journal BioScience. About half of those lost to turbines arehoary bats, which migrate long distances seasonally throughout North America.Eastern red and silver-haired bats, commonly seen in Central Park in NewYork City hunting insects at night, are also being killed by turbines bythe tens of thousands.
8, We can’t afford to lose these creatures.In the Northeast, all of our native bat species eat insects. One little brownbat can eat 1,000 mosquitoes in an hour, reducing the potential formosquito-borne diseases. A colony of 150 big brown bats can protect crops from up to 33million rootworms over a growing season. The Mexican free-tailed bats ofBracken Cave in south-central Texas consume about 250 tons of insects everysummer night. The natural pest control provided by that species acrosseight Texas counties has been valued at nearly $750,000 as it protects the $6million summer cotton crop. Nationwide, the value of bats as pest controllers isestimated to be at least $3.7 billion and possibly much more. (This leaves outthe value of two other very important services that bats provide: controllinginsect-borne diseases and pollinating commercially valuable plants.)
9, Today, genetic engineering may seem toprovide an effective way to protect crops from insects, but pests have alreadydeveloped resistance to some of these products. Insects also readilyevolve resistance to chemical insecticides, and increased use of these chemicals wouldcome at a great cost to human health. But bats have shared thenight skies with insects for at least 50 million years, and they know how to huntand eat them.
10, Fortunately, we can reduce themortality caused by wind farms, which areoften located on windy routes favored bysome migratory bats. Wind turbines usually switch on automatically at wind speedsof about 8 to 9 miles per hour, speeds at which insects and bats areactive. But if, during times of peak bat activity, energy companies recalibratedtheir turbines to start at a wind speed of about 11 miles per hour, which is toowindy for insects and bats to fly, turbine-related deaths could be reduced by44 to 93 percent, according to a 2010 study published in the journal Frontiersin Ecology and the Environment.The effect on power output would benegligible — less than 1 percent annually.
11, Threats to bats also threaten us. Weshould step up research on the prevention and cure of white-nose syndrome. Andwe should require energy companies to take steps to protect batsfrom collisions with wind turbines. It is foolish to spend enormous sums to createpesticides and transgenic crops to fight insects, while investing little toprotect bats, our most efficient insect fighters.