Friday, April 24, 2015

Episode 263 (4-27-15): Bats and Water

CLICK HERE to listen to episode audio (4:20)

Transcript of audio, notes on the audio, photos, and additional information follow below.

All Web addresses mentioned were functional as of 4-24-15.


From the Cumberland Gap to the Atlantic Ocean, this is Virginia Water Radio for the week of April 27, 2015.

This week, we feature sounds that are especially mysterious, because special equipment and processing were needed for humans to hear them at all!  Have a listen for about 15 seconds and see if you can guess what kind of animal made the sounds.  And here’s a hint: If you’re a night-flying insect, high-frequency waves might cause the last echo of you.


If you guessed bats, you’re right!  Special techniques can make audible to humans the ultrasonic waves that bats emit and receive to navigate and detect food—a process called echolocation but sometimes referred to as sonar.  Alex Silvis, a researcher with the Virginia Cooperative Fish and Wildlife Research Unit, recorded and processed the sounds you heard, from the Hoary Bat, Red Bat, and Northern Long-eared Bat.  Those are three of the 17 bat species known to occur in Virginia, out of over 1000 species worldwide.

While some bat species eat fruits, nectar, other vertebrate animals, or blood in the case of vampire bats, all Virginia species feed on night-flying insects, a special ecological role made possible by bat echolocation and flying abilities.  And many bats seeking insects find them near water.  Many aquatic insects—such as mayflies, blackflies, and stoneflies—develop from underwater juveniles to winged adults, and bats forage near water to prey on the emerging adults.

Water is also an important aspect of the caves that many bats use for resting, reproduction, or winter hibernation.  Many caves are formed by groundwater, and caves offer high humidity to reduce bat dehydration during hibernation.  Unfortunately, cave humidity’s also good for White-nose Syndrome, a fungal disease that’s killed millions of bats in eastern North America since 2006.  Besides that disease, other threats to certain bat species in Virginia or elsewhere include habitat loss or contamination, disturbance during hibernation, human hunting for food, and humans’ perceptions—sometimes exaggerated, or even mythical—of bats as disease-carriers, crop destroyers, or vampires.

NOT exaggerated or mythical, though, are bats’ importance to humans as insect eaters and as plant pollinators, and water’s importance to bats.  As the Cooperative Research Unit’s leader Mark Ford put it, “Any given bat on any given night probably foraged over or near water.”  So we close with some bat and water-insect music: a short excerpt of “Little Brown Bats Eating Mosquitoes,” by Timothy Seaman of Williamsburg.  Thanks to Mr. Seaman for permission to use this music, and thanks to Alex Silvis for the bat sounds.


For other water sounds and music, and for more Virginia water information, visit our Web site at, or call us at (540) 231-5463.  From the Virginia Water Resources Research Center in Blacksburg, I’m Alan Raflo, thanking you for listening, and wishing you health, wisdom, and good water. 


The recordings of bat echolocation sounds were provided in March 2015 by Alexander Silvis, a postdoctoral research associate with the Virginia Cooperative Fish and Wildlife Research Unit and the Virginia Tech Department of Fish and Wildlife Conservation.  Thanks to Mr. Silvis for permission to use the recordings, and thanks to him and to Dr. Mark Ford, leader of the Cooperative Research Unit at Virginia Tech, their help with this episode.  More information about the Cooperative Research Unit is available online at

“Little Brown Bats Eating Mosquitoes,” from the 2004 CD “Virginia Wildlife,” is copyright by Timothy Seaman and Pine Wind Music, used with permission; this music was previously used as the feature of Virginia Water Radio Episode 78, 9-5-11.  Mr. Seaman’s Web site is  The “Virginia Wildlife” CD was a collaboration between Mr. Seaman and the Virginia Department of Game and Inland Fisheries to celebrate Virginia’s natural resources and support non-game wildlife programs.  “Little Brown Bats Eating Mosquitoes” was composed in honor of Virginia’s Non-Game Wildlife Tax Check-off; information about Virginia’s program for contributions to organizations and programs through tax check-offs is available online at


The two photos above, taken in caves in West Virginia, are of Virginia Big-eared Bats, Corynorhinus townsendii virginianus, designated in 2005 as Virginia’s state bat.  This bat is listed on both the federal and state endangered species lists.  For more on this species, see the Virginia Department of Conservation/Natural Heritage Division Web site at  Photos by Craig Stihler (upper photo) and Jeff Hajenga (lower photo), made available for public use by the U.S. Fish and Wildlife Service’s National Digital Library, online at

Sign in Virginia Tech's Liberal Arts Building, April 23, 2015.  Photo courtesy of Eli Archer.


Bat Classification and Species

Bats are mammals, and are the only ones capable of self-propelled flight.  The over 1000 species of bats worldwide are classified in one order, the Chiroptera, consisting of two main groups: the family of megabats, also called the Old World fruit bats; and several families of microbats, including all of the insect-feeding bats found in Virginia.  The 17 species that have been recording in Virginia are among 45 native species in the United States.  Bat species occurring in Virginia are listed at the Virginia Department of Game and Inland Fisheries’ (VDGIF) “Bats/Bat Facts” Web page, online at  Each species name is linked to additional details about the species.  According to that Web page, “Three of the bat species in Virginia are federal endangered species (Gray Bat, Indiana Bat, and Virginia Big-eared Bat); the Rafinesque's Big-eared Bat, also known as the Eastern Big-eared Bat, is a state threatened and endangered species.”

Bat Habitats

According to VDGIF’s “Bats/Bat Facts” Web page, online at, Virginia’s bat species “are divided into two categories: cave bats and tree bats.  Cave bats hibernate in caves, while tree bats hibernate in leaf clusters, under decaying logs, in hollow trees, or sometimes in abandoned mines or old buildings.”  Cave-hibernating species may use similar areas, such as mines or wells.  Different bat species also use a variety of habitats for roosting (daytime resting), including caves, trees, buildings, other structures, and mines.

Bat Population Status

Decades of Bat Observations Reveal Uptick in New Causes of Mass Mortality, U.S. Geological Survey News Release, 1/19/16.

Bat Sounds

Bats make other sounds, or “vocalizations,” beside the ultrasonic (or very high frequency) sounds used in echolocation of prey or obstacles.  Bat communication includes vocalizations between females and young and various calls by males used in mating courtship and in defending territory.

Virginia Cave Week

The observance for 2015 runs April 19-25, and bat conservation is the 2015 theme.  The Virginia Department of Conservation and Recreation’s April 8, 2015, news release about Cave Week 2015 is online at this link.  More information about the week, bat conservation, and bats connections to Virginia caves and other karst features is available from the Virginia Cave Board, online at



Used for Audio
John D. Altringham, Bats—From Evolution to Conservation (Second Edition), Oxford University Pres, Oxford, U.K., 2011.

W. Mark Ford and Hannah Hamilton, “Identifying Bats By Sound; Following White-Nose Syndrome, Acoustic Method Best for Sampling Bats,” U.S. Geological Survey News Release, 2/12/14, online at

Michael J. Harve, J. Scott Altenbach, and Troy L. Best, Bats of the United States, Arkansas Game and Fish Commission/U.S. Fish and Wildlife Service, Asheville, N.C., 1999.

Phil Richardson, Bats, Firefly Books, Buffalo, N.Y., 2011.

U.S. Fish and Wildlife Service/Midwest Region, “Glossary of Acoustic Bat Survey Terms,” online at

U.S. Fish and Wildlife Service’s White-nose Syndrome Web site, online at

Virginia Department of Conservation and Recreation/Natural Heritage Division, “Bats of Virginia,” online at

Virginia Department of Game and Inland Fisheries, “Little Brown Bat,” online at

Virginia Department of Game and Inland Fisheries, “Bats,” online at

Additional Sources
Bat Conservation International, online at

National Speleological Society, online at

U.S. Geological Survey/Western Ecological Research Center, “Bat Vocalizations—Search Phase Call,” online at  These are recordings of bat echolocation sounds for which the frequency has been lowered to make them audible to humans (except for one species, where the sounds are already audible).

Virginia Department of Conservation and Recreation/Natural Heritage Division, “Cave and Karst Protection,” online at


Groundwater | EP178 – 9/9/13
Mosquitoes | EP78 – 9/5/11
True bugs | EP237 – 10/27/14
True flies | EP221 – 7/7/14
Virginia caves | EP158 – 4/22/13

For a subject index to all previous Virginia Water Radio episodes, please see this link:


This episode may help with the following Virginia’s 2010 Science Standards of Learning (SOLs):

Grades K-6 Earth Resources Theme
4.9 (Va. natural resources)
6.9 (public policy decisions on management of renewable or non-renewable resources)

Grades K-6 Earth Patterns, Cycles, and Change Theme
3.8 (animal life cycles)
3.9 (water cycle and water as essential for living things)

Grades K-6 Life Processes Theme
K.6 (distinguishing characteristics of organisms)
1.5 (basic needs of organisms)
2.4 (animal life cycles)
3.4 (adaptations)

Grades K-6 Living Systems Theme
2.5 (living things as part of a system)
3.5 (aquatic and terrestrial food chains)
3.6 (aquatic and terrestrial ecosystems, including biodiversity and shared resources)
4.5 (ecological interactions)
6.7 (natural processes and human interactions that affect watershed systems; Va. watersheds, water bodies, and wetlands; and water monitoring)

Life Science Course
LS. 4 (organism features and classification)
LS.6 (ecosystem interactions)
LS.8 (population interactions)
LS.9 (organism adaptations for particular ecosystems)
LS. 10 (organism and system changes seasonally and over time, including hibernation)
LS.11 (relationships between ecosystem dynamics and human activity)

Earth Science Course
ES.8 (freshwater resources, including groundwater and karst areas, and influences by geologic processes and the activities of humans)

Biology Course
BIO.8 (dynamic equilibria and interactions within populations, communities, and ecosystems, including analysis of the flora, fauna, and microorganisms of Virginia ecosystems)

Virginia’s SOLs are available from the Virginia Department of Education, online at