A regular Source feature, Undercurrents explores issues, ideas and events as they develop beneath the surface in the Virgin Islands community.
If ever a creature was misunderstood, it is the poor, little, universally maligned bat. Not satisfied to defame the winged mammal as disease-bearing, generations of humans have crafted slanderous tales of bats cavorting with witches and warlocks and preternatural vampires, luring innocent folk into caves so deep they stretch into the netherworld.
Assistant professor Renata Platenberg of the University of the Virgin Islands isn’t interested in dark legends. She’d rather solve the real bat mysteries – like just how do they communicate with one another and where do they go when their habitat is disturbed?
“The only mammals native to the Virgin Islands are bats,” Platenberg said. But despite their long history here, we know very little about them.
“It’s really hard to find where they live,” Platenberg said, although she and her team of volunteers and students have located numerous colonies over the years. One colony or “roost” on the Northside of St. Thomas has about 30 bats. But there’s no telling how many roosts there are. “We really, really do not have a big grasp of their numbers.”
Their lifespan? “We don’t even know that.”
Formerly with Fish and Wildlife at the Department of Planning and Natural Resources, Platenberg began seriously studying bats here several years ago. Since 2006, she has conducted public “Meet the Bats” tours in a favorite research site, Magens Bay.
“In 2008 we started doing the intensive monitoring” of bat colonies. Since 2011, “we’ve been tagging them.” The researchers use nets to capture the bats, which are then released once they have been tagged and their vital statistics noted and recorded. Platenberg said she’s handled and collected data on 1,000 bats.
There are five species of bats in the Virgin Islands, and Platenberg has found all of them at Magens Bay, though she theorizes that some may live nearby and fly into the bay area only to forage. Artibeus jamaicensis, Molossus molossus and Noctilio leporinus are found either widely or very widely throughout the Caribbean. Brachyphylla cavernarum is only in the Lesser Antilles. And the small Stenoderma rufum is found only in Puerto Rico and the Virgin Islands.
The Molossus molossus eats only insects, making it best friends with anyone who doesn’t like mosquitoes. Noctilio leporinus likes fish. And the others are primarily fruit-lovers, although they will also eat insects.
Besides handling pest control, bats provide a great source of plant pollination. Platenberg said they also are more efficient than birds in distributing seeds, making them really valuable for reforestation after a hurricane.
“We want to know how to keep them,” she said. That’s one reason to study them and why the research needs to be long term.
A few years ago, the government cleared out many of the trees in the Magens Bay arboretum, so it could return the area to the coconut grove it used to be. The bats didn’t like the change. “They’re not using that area anymore,” Platenberg said.
So we know that the bats will leave if their habitat is disturbed. But Platenberg has more questions: “How far do they go?” and “Do they come back?”
There has been little funding for Platenberg’s work. She relies on a core group of volunteers and “a couple of graduate students,” one of whom is studying the genetic makeup of Caribbean bats as part of research into their migration flyways.
“Four of us are regulars,” she said. “We all donate Friday nights.” They even supply their own gloves and flashlights.
The limited funding also means most of their research has been confined primarily to one island, St. Thomas.
Their efforts got a boost in September with a small grant from the Community Foundation of the Virgin Islands that allowed for the purchase of three song meters to record bat sounds. The sounds are recorded digitally, so they can be downloaded to a computer and viewed as well as played back as audio.
On Meet the Bats nights, people can listen in on bat echolocation calls, the sounds bats use to guide them in the dark. But the new monitors go beyond echolocation.
Bats have “a range of vocalizations,” Platenberg said. Researchers are just beginning to sift through and categorize them, but already it’s apparent that “they have love songs; they have territorial songs.”
In a precursor to the current study, a visiting biologist at UVI last spring recorded sounds emanating from one colony of bats and later played them near another roost. The bats reacted to the recording with a barrage of territorial songs, apparently meant to repel intruders.
The song study is being conducted more widely than some others, with recordings in various locations in the British Virgin Islands as well as the U.S. territory.
“We’re putting them near known roosts,” Platenberg said. One meter has already been used on Anegada and is due to return to St. Thomas with its data this week. “We’re building a library of calls,” she said.
The work will continue for at least several months. It may give the researchers a better idea of the number of bats on the islands as well as a better understanding of their habits and their importance in the ecosystem.
Platenberg does not romanticize bats. Yes, a tiny percentage of bats can carry rabies, and most recently they have been linked to Ebola. But transference to humans is extremely rare anywhere, and in the Virgin Islands, neither of those diseases is present, so bats here can’t and don’t carry them.
With danger nil and benefits abundant, Platenberg suggests we get to know our fellow creatures better.
“If we stop being so afraid of nature and allow it into our lives, it can do a lot for us,” she observed.