Wildlife & Nature

R.I.’s Mosquito-Devouring Bat Population Hurting


Bats may be a nuisance to homeowners, but they are valuable for the environment. They eat a lot of mosquitoes and bugs that harm crops. (istock)

There are bats in Rhode Island. They inhabit barns in South County, high-rises in Providence and mansions in Newport. The problem is there are just a lot fewer of them than there were a decade ago, according to local bat experts.

Matt Grady, owner of animal removal company BatGuys Wildlife Service, has collected bats from attics and chimneys across Rhode Island and eastern Massachusetts for almost two decades. He began seeing their numbers decrease significantly with the onset of white-nose syndrome.

The disease has decimated as much as 90 percent of migrating bats as they wintered in caves and abandoned mines in upstate New York, Vermont and Canada. The death of millions of bats has significantly reduced the once-familiar little brown bat in the region. Other less-common species, such as the Eastern red, hoary and silver-haired bats, are all but gone, according to Grady.

“We used to have a healthy population of little brown bats … but they were wiped out by white-nose syndrome in 2006-2007,” he said. “I haven’t seen one since.”

The little brown bat, which is about the size of a field mouse and weighs less than a half-ounce, is considered a country bat found in rural South County, along the Connecticut border, and in the Foster and Glocester area. They were most abundant in Tiverton and Little Compton.

Charles Brown, a wildlife specialist with the Rhode Island Department of Environmental Management (DEM), said little brown bats have been hit hard by white-nose syndrome, but he knows of at least a dozen colonies that summer in Rhode Island barns.

Since 2010, Brown has examined the bats tested for rabies by the state Department of Health and has only seen one little brown bat among about 1,500 collected.

“There is no question the number of little brown bats that spend the summer months in Rhode Island has declined,” he said.

University of Rhode Island professor Peter August said white-nose syndrome has “taken one of our most common bats and turned it into one of our rarest.”

August, co-chair of URI’s environmental science graduate program, said he’s hopeful that surviving little brown bats will have offspring that are immune to white-nose syndrome. Both he and Brown have observed that the dramatic die-off of little brown bats may have hit its low point and the population could, at least, be stabilizing.

“The reality is it’s going to take a long, long time for anywhere in the Northeast to return to as we had pre-white-nose syndrome,” August said.

Another problem for bats, as well as birds, are wind turbines. Large turbines are often built along bat migration routes, where bats mistaken them for trees. The bats are struck by the blades or implode from the sudden change in air pressure. A 2013 study in the journal BioScience estimated that wind turbines kill some 600,000 bats annually.

“It’s becoming a real issue as people start to study this,” Brown said. Wind energy, he said, “may not be as green as we think it is.”

Bats are also suffering from a loss of habitat. Smaller bats likely flourished centuries ago when much of southern New England was wooded and swampland. Trees provided shelter and swamps were rife with mosquitoes — the main food for smaller migratory bats like the little brown bat.

The influx and proliferation of houses and other structures, however, have proven suitable for bats that overwinter, such as the big brown bat.

Contrary to its name, the big brown bat is not much larger than the little brown bat, weighing less than an ounce and with a body size of 4-5 inches. However, they have a broader diet than migratory bats, eating moths, beetles and other insects. As a result, the big brown bat is now the most common bat in the region and appears to be thriving. They can be found in nearly any structure.

Bats may be a nuisance to homeowners, but they are valuable for the environment. They eat a lot of mosquitoes and bugs that harm crops. For example, swarms of bats provide valuable pest-control for cotton and corn crops in Texas and Oklahoma.

“There are really important to controlling our mosquito population,” said Nicole Souza, who leads bat-watching tours for the Norman Bird Sanctuary in Middletown.

Despite its size, Rhode Island conducts a lot of bat research. James Simmons, a professor of neuroscience at Brown University, has studied bats since 1965. His work, much of it funded by the Office of Naval Research, focuses on the auditory system of bats and its application to sonar. He’s been featured, along with fellow Brown University professor Sharon Swartz, who studies bat flight, in a bat documentary.

Bats are the largest group of mammals in the world. Here are some facts about local bats and bats in other regions:

There are about 1,300 bat species in the world. About half are threatened or endangered, largely because of habitat loss, disease and wind turbines.

All bats found in New England eat night-flying insects such as mosquitoes, moths, beetles and even wasps. They typically consume 2,000 or more insects a night. Some tropical bat species eat fruit and nectar and are important pollinators. Other non-New England species feed on frogs, small fish and rodents.

As insects disappear when it gets cooler, so do bats. Migratory bats fly south or head north to winter in mines and caves.

Bats are the only mammal capable of flying, which they do mostly at night while feeding. For centuries, inventors and scientists have tried, and mostly failed, to replicate the unique flying ability of bats.

Female bats give birth to one pup annually. About 90 percent of newborn bats die in their first year. Those that survive live up to 40 years.

In the past 50 years, fewer than 40 people have contracted rabies from wild bats. Fewer than 1 percent of bats have rabies. Still, health officials recommend that any bat found in a home get tested. Click here for more safety tips.

Flat, wooden maternity roosts are ideal for attracting bats. There are many in Rhode Island, including three at the Norman Bird Sanctuary. They are easy to build and typically host 150 to 200 bats.


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