November 9, 2019 A Beautiful Crisp Morning (by Angie Stober)
Dr. Andrew Edelman, professor at the University of West Georgia, enlightened about 12 attendees of the FOMR monthly Walk and Talk to the nature and importance of bats in our eco-system. Bats are found throughout the earth except the Artic and Antarctica. There are more than 1300 species of bats world wide. The myths and fear of bats are unfounded. It is recommended that untrained people should not handle bats because a small percentage (less than 1%) carry the rabies virus.
There are two distinct types of these often misunderstood mammals: Megabats and Microbats. Megabats, quite different from Microbats, are found in the Old World. They are referred to as the Farmers of the Rainforest, because many are fruit eaters and distribute seeds throughout their range.
Microbats were the major focus of our discussion as they comprise the species found here. These bats can range in size from 1.1 to 6 inches, with varying wing span dependent on species. There are 16 species of bats found here in Georgia. (The Georgia DNR has an excellent website on bats of Georgia https://georgiawildlife.com/GeorgiaBats). These microbats use echolocation to detect objects and contrary to the old adage “blind as a bat” they have good vision. They are one of the few mammals to use sonar to navigate in flight, forage for food and find their roast. They use a complicated sequence of calls and can modify the ultrasonic wave to get more details on the size, range, position, speed and flight direction of the prey. They can even jam other bats feeding calls. Most bat echolocation calls are out of the range of humans who top out at 20kHz, while bat calls range from 9-200kHz.
Our Georgia bats include many tree bats. The Red bat is a common midsize species, sometimes confused with the Seminole bat which is about 4.5 inches in length with a 12 inch wing span. Both frequently hibernate in leaf litter. Hoary bats have a yellow mane and often have twin pups. It is is the largest microbat measuring 5-5.7 inches, with a wing span of 15 inches which allows it to fly high and migrate long distances. These bats are among those most likely to be killed by wind turbines. Big Brown bats are second largest at 4-5 inches in length with a 13 inch wing span. They are most likely to be the attic dweller. If you do have bats in your attic call someone to safely remove them (the DNR site will direct you). These bats have a powerful bite with large teeth to eat moths and large hard bodied insects like beetles. Evening bats are half the size of the Big Brown. Both like bat houses. Rafinesque’s Big eared bats have large folding ears, may mate in the air and roost in hollow trees. Southeast Triclor bats roost in trees in summer and are found in culverts in winter. Mexican Free-tailed batsare medium sized and roost in large numbers. They present quite an amazing nightly show in Austin, Texas at the Congress Avenue Bridge from March- October. Indiana bats are mouse eared, medium sized at 1.2-2.0 inches long and live in hardwood and pine forest. The Gray Northern Long-eared (roost in buildings in colonies), the Small Footed bat, and the Indiana bat have been hard hit by white nose syndrome and loss of habitat. Some species are more group oriented while others are loners. All are most active April – October.
All bats are difficult to study since they are nocturnal, small and evasive. However Dr Edelman is involved in a project in the Talladega National Forest in collaboration with Jonathan Stober USFS, where they net bats, identify, evaluate, weigh, measure, place radio tags on to track for about 2 weeks, determining roost site and feeding habits. They have studied the effect of prescribed fire and have found that bats seem to prefer burned over areas of the forest.
During summer and fall microbats go into a feeding frenzy to fatten up on insects (one can eat more than 300-500 mosquitoes in an hour) so they can survive the winter when they become torpid, which is lowering their body temperature like a mini hibernation. They hibernate in leaf litter, under bark of trees, in hollow trees, cracks in post, storm water sewers. (They prefer concrete square ones and are found in these culverts along I-20). Some species prefer caves, rock outcrops, etc.
The gestation period for most micro bats is about 6 to 9 weeks. The female gives birth usually to 1 fur-less pup. Some species have twins. The pup drinks milk from the mother and remains in the roost while the mother forges for food until they are able to fly and forage in about 3-4 weeks. Once a bat reaches maturity its morality rate is low unless it contracts white-nose syndrome, a fungus that attacks the immune system. The fungus is spreading across the U.S. and is believed to have come from the Old World. It is most detrimental on cave dwelling species and spread by cave explorers. The tree bat species are less likely to be affected by the fungus because they hibernate for a shorter period.
Only 3 species of bats feed on blood (vampire bats) and these live in Central and South America. Vampire bats have a cool behavior in that they share blood – if one bat is in need another will help. They have also provided medical advancement in anti-coagulation issues.
Bats are declining in numbers due to loss and fragmentation of habitat, white nose syndrome, wind turbines (low pressure in area effect lungs of bats), deforestation, disturbance in caves (some caves are now gated to manage disturbance). Bats are a critical part of our eco-system saving farmers billions of dollars in pest control and protecting humans from insect borne disease.
Things we can do to help bats; Educate the public, Protect habitat, Put up bat boxes, Remove safely from homes, Practice clean caving by decontaminating all gear, Join Georgia Bat working Group and volunteer,
Practice Bat conservation and Join Bat Conservation International. A bat house pattern was available for attendees.
Next year we can plan a Walk and Talk for an August evening and observe bats in action.