Refuting bats’ bad rap

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April 4, 2017 - 12:00 AM

Mention bats, and the first thing that comes to mind for most folks is rabies.
Dr. Merlin Tuttle cringes at the thought. At 75, the Kansas University graduate is one of the foremost authorities on the flying mammals and he’s quick on the draw when comes to their defense. He has been described by National Geographic Magazine as “the world’s most famous bat biologist and booster, (having) … devoted his life to studying, demystifying and helping conserve bats.”
A motorist has a better chance of dying on a one-mile journey than contracting rabies from a bat, he said: “One or two people a year in the U.S. and Canada die from rabies they got from a bat. And, it’s from being stupid twice. First, they pick up a bat that’s sick and can’t fly, and get bitten. Then they don’t get treatment.”
Bats have a bad rap for being creatures of the night and sinister-looking in the eyes of many people. Tuttle refers to them as being “cool,” and notes that many, when viewed without prejudice, are among nature’s most attractive creatures
They vary greatly in size, color and where they live, but all have one thing in common, they eat insects, accumulatively by the trillions every night. Tuttle’s contention, well-founded in research, he said, is the advent of universal use of pesticides after World War II was a huge mistake, that if praying mantises, frogs, lizards and particularly bats had been left to the task “we all would be better off.”
Tuttle also pointed out pesticides have become stronger and more deadly, as insects acquired immunity. He noted studies where insects are being controlled without pesticides in crop fields, with natural flora and fauna nearby, including bats that covet flying insects as a protein-rich source of sustenance.
It is common to find insects flooding the sky for an hour or so at dusk, and then retreating to ground cover when night falls and bats take flight, to sweep the air for fodder.
Bats, whom Tuttle thinks are among the most intelligent of wild things, also recognize their need to position feeding flights where they’re most likely to find an ample supply of insects, and then protect those sites.
He cited moths that migrate from Mexico early in the year, with females burdened by hundreds of eggs. Bats’ internal calendars time their reception and save cotton, corn and other crops in Texas from being blighted by the moths and their hordes of offspring.
The moths continue on north, so, Tuttle reasoned, “what they eat in Texas, and along the way, saves crops all the way into Wisconsin.”
Another analogy: If two house flies were given ideal mating conditions, including an absence of predators, a computer model shows in a year’s time that all of the globe would be inundated to a depth of a foot.

TUTTLE was in Iola over the weekend to confer with Don Erbert and Steve Barlow, who build bat houses that are daytime residences for up to 4,000 bats. Their aim was to find ways to make the rest stops more attractive.
The Erbert-Barlow team started constructing bat houses a few years ago and at last count had ones with their brand erected in 15 states. With Tuttle’s assistance, they next will go international, shipping bat houses to Panama.
The houses are a series of plywood separated by half-inch or so spacers. Bats, which sleep during the day hanging from their feet, usually in caves, on the undersides of limbs or in hollow trees, land on the edge of the plywood and scoot backward into the enclosure.
The local builders and Tuttle discussed whether roughing the plywood would be conducive, by giving bats’ tiny feet a better surface to grab hold. They also talked about whether ventilation along the sides would be helpful during hot summer days.
Bats bear their young like other mammals and, depending on species, can have between one and four “pups,” as Tuttle calls newborns.
Mating occurs in the fall with birth in early spring. To equip themselves for cold winter weather, “moms have to put on fat” for their sedentary time of the year. A remarkable event is that female bats have the ability to control their gestation period, depending on nutrition and weather.
Another extraordinary fact is that bats can abort an embryo and absorb its nutrients if a harsh winter or poor feeding season occurs prior to hibernation.
They also move within a roost area, to congregate and to find a suitable temperature when a group effort isn’t possible.
While most feeding occurs during the run-up to winter, Tuttle said he has seen bats returning to their roosts after searches for insects during blizzard conditions.
Males are a bat of another color when it comes to hibernation preparation. They burn up much of their reserves during mating — bats have been known to fly up to 100 miles an hour — and go on feeding frenzies when impregnated females, already fattened, snuggle up in hibernation.
The reverse also is a hibernation logarithm: While males hang and sleep in early spring, the females, even though they can control gestation, have depleted their fat reserves providing for themselves and the soon-to-be addition, and must gulp down every insect they find. Later the males, aroused when their fat is depleted, join in.
Baby bats, imbued by heredity, follow their parents’ tendencies, including, when cold weather hangs on in spring, drawing together to stay warm. Very quickly they fly from the roost and instinctively begin to eat insects.
Bats also adjust their body temperature to fit circumstances.
Tuttle said that during a yearlong, once-every-10-days survey to measure body temperatures, he found a bat that looked like an icicle, hanging asleep, with all but its nose covered with ice. He figured it was dead, but chipped away the ice, found a 27-degree reading with a rectal thermometer and then, when the bat warmed, watched it squirm around, finally alive.
His supposition is that bats have the ability to produce a substance in their blood similar to antifreeze used in vehicle radiators.

“WE’RE GETTING more and more arrogant about thinking we can control nature with pesticides,” Tuttle said. “We’re not paying attention to bats declining greatly.”
He noted that Mammoth Cave, now a national park in Kentucky, once was home to huge numbers of bats, but now that it is a tourist destination, the bats have been ushered elsewhere, or killed.
The estimate is that 33 million pounds of pesticide are used annually in the U.S., including a large portion for mosquito control in towns and cities, Tuttle said. But, “people don’t realize that many of those chemicals can lead to dementia and Parkinson’s Disease.
“Bats are our best hope for turning things around,” he said. “It’s incredible what bats can do to control insects. One cave with 10 to 20 million bats can eat up to 100 tons of insects a night,” with the bats often taking flights of up to 20 miles to preferred hunting grounds.
Not only does pesticide reduce bats’ food source, the chemicals themselves can have a debilitating effect on bats. Tuttle said the chemicals can kill a bat directly, and also build up in fat and migrate to the animal’s brain as fat is consumed.
“The best way for people to live in harmony with nature is to keep the bat population in balance” with insects, he said.

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