An Unprecedented Bat Die-Off Could Devastate U.S. Agriculture

By BRUCE KENNEDY Posted 9:45 AM 10/12/10

 Most people don’t love bats, but like good health, you’ll realize that you miss them after they’re gone. Experts believe many species of bats may vanish pretty soon, and their disappearance could bring profound and long-term changes not only to the environment but also to agriculture, landscaping and gardening across North America.

For several years now, scientists have been sounding alarms about a devastating fungus, White-Nose Syndrome (WNS), that has literally decimated bat populations in the Northeastern U.S. The fungus leaves a white substance on the bat’s nose, wings and body, and disrupts the bat’s hibernation patterns, forcing it to burn through its fat reserves, which quickly leads to starvation. Earlier this year, a survey of the bat population in New Jersey estimated that 90% of that state’s bats had been killed off.

“This is on a level unprecedented, certainly in mammals,” says Rick Adams, a biology professor at the University of Northern Colorado and a renowned bat expert. “A mass extinction event, a thousand times higher than anything we’ve seen. It’s going through [bat colonies] like wildfire, with 80% to 100% mortality.”

“The disease is absolutely devastating, it’s unprecedented,” says Mylea Bayless, a biologist with Austin, Texas-based Bat Conservation International. “It’s causing population declines in wildlife that we haven’t seen since the passenger pigeon.”

Bayless notes that bats have slow reproductive rates, usually giving birth to just one pup a year. So bat populations, she says, are going to be very slow to recover, “if they ever do recover.” The disease, adds Bayless, “is moving at a pace that’s astonishing, about 450 miles per year. In four short years, it’s now closer to the Pacific Ocean than it is to its point of origination in Albany, N.Y.”

Your Billion-Dollar Bug Eaters

You might be saying good riddance, but think again. Bats are the primary predator of night-flying insects. That not only includes pests like mosquitoes but also insects like corn earworm moths and cotton bollworms. In their caterpillar forms, those insects can destroy crops. A 2006 study of several counties in South-Central Texas concluded that the local bat population had an annual value of over $740,000 a year as a pest control — or up to 29% of the value of the local cotton crop.

 A bat eats 60% to 100% of its body-weight in insects every day. Adams says one colony of Mexican free-tailed bats in Colorado’s San Luis Valley, an important agricultural region, “pulls about 100 metric tons of insects out of the air in a year.” And having bats in agricultural areas, he says, tends to move insects out of those areas, creating less need for dangerous and expensive pesticides.

And like honey bee colonies — which have also been facing massive die-offs in recent years — some bats are important pollinators and seed-distributors. Adams says bats are crucial to the reproduction of tropical fruits like mangos, papayas, figs and wild bananas. And in Arizona, bats are the primary pollinators for three large cactus species that support much of the region’s ecosystem.

Government and Researchers Fight Back

The fungus associated with WNS is widespread in Europe, but it doesn’t affect bats there. No one is sure yet how it became so lethal to North America’s bat population — but there’s a possible human element. Scientists says WNS spores have been found on the clothing and gear of people exploring caves containing bat colonies. The pattern of its spread is also inconsistent with bat migration. “It went from Tennessee to Missouri and then to Western Oklahoma,” says Adams, “and it doesn’t seem like it would be moving like that if it was just bats.”

In the meantime, humans are fighting back. Adams is hosting a conference on the crisis later this month in Denver. The event is expected to draw hundreds of bat experts from around the world. The Forest Service is banning visitors to the thousands of caves and abandoned mines that dot the landscape in at least five Rocky Mountain and Great Plains states. And the Fish and Wildlife Service has awarded $1.6 million in grants for WNS research and control.

“But we all know that’s a drop in the bucket for a disease that’s sweeping the country and killing 95% of an entire group of animals,” says Bayless. “For some people, that may seem like money. . .not well-spent, but [what are] the economic and ecological consequences of losing an entire species? A little bit of money spent now will save us in the long term.”

Tagged: agribusiness, agriculture, bat, bat colony, bat die-off, bat disappearance, bat fungus, bats, bees, colony collapse disorder, conservation

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