Thursday, August 15, 2013
With a high-tech detector atop a make-shift pole, Auburn University graduate student Lydia Moore spends quiet hours near water from sundown to sunrise listening for the call of the bats.
Moore wants to know if bats behave differently over the water than over land. Very little research has been done on activity of bats in the lower coastal plain of South Carolina, said Moore, a Charleston resident. “We really don’t know how they are using these habitats.”
As part of her master’s thesis, Moore said she is observing “how bats use wetland habitat to determine if there is a difference in activity over fresh water, salt water and brackish water and within each of these habitats whether vegetation or lack of vegetation affects activity.” At each site, she also traps insects periodically to measure their number and diversity.
“I think bats are going to be most abundant over fresh water because they need to drink, but there may be more foraging activity over brackish and salt water than was previously thought,” she speculated based on early research that began in May.
“Most of the research on bats in South Carolina has been conducted in terrestrial habitats,” said Moore, who earned bachelor of arts degrees in biology and environmental studies from Oberlin College in Oberlin, Ohio. “Most of this research has shown that bats selectively forage over water within terrestrial systems and prefer areas with a high diversity of roosts. The lower coastal plain of the state has the greatest level of structural diversity of the four ecoregions in the state, such as Spanish moss, swamps, bridges, trees with large diameters and buildings. We also have barrier islands, which may act as resting points during the autumn migration.”
Magnolia Plantation and Gardens is one of five sites where Moore is collecting data. Her work will end in mid-August. She’ll return next spring with hopes that she can conclude her research and master’s thesis in the spring of 2015. Moore is also collecting data at James Island County Park, Caw Caw Interpretive Center, Bear’s Bluff Fish Hatchery on Wadmalaw Island and Church Creek on Johns Island. Bats are natural predators to insects that harm crops grown for food.
Moore uses an electronic bat detector, which records bat calls, at six sites at Magnolia. The monitor is placed in a bucket and the bucket is mounted at the top of a pole. Detectors are positioned over old rice fields, along the Ashley River, and over ponds near the Audubon swamp garden. Her study has shown that bat activity from sunset to sunrise falls into two groups. “There are early fliers and then there is generally a lull around midnight followed by activity before sunrise,” she said.
Bat calls differ depending on the species. So far, Moore has recorded the calls of six species. The detectors, she said, has picked up the calls of the Eastern Red Bat/ Seminole Bat, Evening Bat, Tricolored Bat, Big Brown Bat, the third largest bat in this area and the largest species in South Carolina, the Hoary Bat.
Although the detector has not picked up the call of the Rafinesque’s Big-eared Bat, Moore said, she knows it is here. “I’ve seen it.”
She has also used a mist net to catch some of the bats. She weighs and measures them and notes their reproductive conduction, sex, age and whether they are juveniles or adults.
Bats are mammals. Bird watcher Perry Nugent has not seen that many at Magnolia. Nugent, who has led Sunday morning bird walks at Magnolia since 1988, is interested in Moore’s research. “I am happy someone knows how to find them because we don’t know much about bats,” he said. “I don’t see bats that often.”
Moore’s research and other bat studies could have long-range implications on where to place wind turbines offshore to produce electricity. Research in other parts of the United States and Europe suggest that bats can fly miles offshore, making them vulnerable to being caught in the revolving blades of wind turbines.
“Of the 14 species of bat in South Carolina, 12 inhabit the lower coastal plain,” she said. “We have a fairly high diversity here. There are 11 species that have documented mortality due to wind turbines in the United States, and eight of these species are in the lower coastal plain of South Carolina. Three of these species account for 75 percent of known fatalities by wind turbines. All three of which have been documented in the lower coastal plain.”
There is a proposal for a 1,000-megawatt offshore wind farm in South Carolina, Moore said. “While it is admirable that South Carolina has a green energy initiative, the decision to build a wind farm should be an informed one. My study is looking at how bats are using wetlands in the ecoregion closest to the coast. It is
these bats, along with migrating bats, that could be hit hardest by turbines. The first step is to learn how bats are using wetland habitats in the lower coastal plain.”