A mysterious, fast-moving disease has now killed as many as 6.7 million bats in North America over the past six years, according to an estimate released today by bat biologists. The new estimate is dramatically higher than the previous one, dating from 2009, that white-nose syndrome had killed 1 million bats on the continent. The disease was first discovered in upstate New York in 2006 and has spread from Nova Scotia to Tennessee, infecting bat colonies in 16 states and four provinces.
"This number confirms what people working on white-nose syndrome have known for a long time -- that bats are dying in frighteningly huge numbers and several species are hurtling toward the black hole of extinction," said Mollie Matteson with the Center for Biological Diversity, which has filed several petitions to save bats and stem the spread of the disease. "We have to move fast if we're going to avoid a complete catastrophe for America's bats."
The new mortality estimate -- which ranges from 5.7 million to 6.7 million -- was agreed upon by biologists who met last week at the Northeast Bat Working Group's annual meeting in Pennsylvania, one of the states hit hardest by the bat die-off. The grim figure follows recent news that a few surviving bats were confirmed in Vermont this past summer -- a discovery that had buoyed hopes that some individuals may have resistance to the devastating disease, meaning they could possibly form the nucleus of a future recovery effort. Overall populations of affected bat species in places like Vermont, New York, Pennsylvania and other parts of the Northeast are down 70 percent to 98 percent since 2006, which also makes the populations more vulnerable to other threats, such as habitat loss, human persecution and environmental contaminants.
The outbreak is the worst wildlife disease epidemic in North America's history. Congress recently directed the Department of the Interior to allot $4 million for research and management of the disease.
"America's bats are in the throes of an unprecedented crisis and some species face the very real prospect of extinction," Matteson said. "While it's heartening to see some money allocated for white-nose syndrome, today's new mortality estimates are a wake-up call that we need to do more, and fast."
White-nose syndrome has affected six bat species so far; it kills them during their hibernation period, when they occupy caves and mines in a state of "suspended animation." The affected bats are insect eaters; their hibernation is a response to a lack of prey available during the winter months. The loss of so many bug-eating bats has likely had an impact on insect populations, including those that are pests on crops. Scientists have estimated that bats save farmers between $3.7 billion and $53 billion per year on pesticides that did not have to be used on crops like corn, cotton, vegetables and fruit because of the help bats give. Since the bat disease has only shown up in the Midwest and South in the last couple of years, the full effects of declining bat numbers on regions more strongly dominated by agriculture than the Northeast may take some time to show up.
The South and Midwest contain some of the largest and most diverse bat colonies in the world. Already one federally endangered bat has been hit by the disease; the Indiana bat has declined by 70 percent in the Northeast since 2006, though it had been on an upward trajectory in that region before the onset of the disease. Scientists fear that as white-nose syndrome spreads in the Midwest, the species' core range, the total population of Indiana bats could plummet. Other bat species are at risk too, and three are currently under review by the U.S. Fish and Wildlife Service for addition to the endangered species list due to the threat posed by white-nose syndrome.
For more information, go to SaveOurBats.org.
