by Barbara French
A rehabilitation colony of Mexican free-tailed bats is sometimes a lot like middle school: a noisy place filled with raging hormones, constant nervous conversation, and boys and girls trying to figure out where everybody fits into this complete little society. The bats chatter frequently, and we have learned to translate some of that exotic language. We have identified about two dozen vocalizations that we can identify with specific behavior.
As a Bat Conservation International science officer and bat rehabilitator for years, I have a large flight cage at my Central Texas home that has been a temporary refuge for many orphaned or injured bats. Teh-Sheng Ma, a University of Texas graduate student in neurophysiology, worked with me to identify, record, and translate many bat vocalizations.
We have learned a lot by watching and recording the sounds in this little captive bat colony. Although we can't hear many of the sounds they make, components of some of their calls are within the range of human hearing. And it appears that they have an elaborate language.
Amanda Lollar of the Bat World Sanctuary first wrote about the apparent meanings of sounds made by free-tails in another captive colony. We have compared the sounds made by the bats in our respective colonies and our observations about related behaviors. Our results are similar. This research is beginning to decode the language of free-tails
Consider this mating ritual that took place recently in my bat cage:
The bat I call Dillon stands at the entrance of his roosting pouch, flaps his wings wildly, and declares: “bzzzzzzz buzzzzzz, nee nee, nee nee, rrrrrrrrrrr.” Blossom pokes her head out of another roosting pouch and looks his way. She creeps slowly towards Dillon, but Guanito, on the other side of the cage, notices her movement. He stands at the entrance to his own roosting pouch and says: “bzzzzzz, bzzzzz, bzzzzz, nee nee, nee nee, nee nee.” Dillon calls back and Blossom stops, listening to the boys as they compete for her attention. Eventually scampering towards Dillon, she responds with a quiet, “ta, ta, ta,” crouching against the cage and lowering her ears in a submissive gesture as he pounces. Dillon pushes his face into her shoulders. “De de de, de de de,” he scolds.
After a few moments, Blossom scampers into his pocket and joins three other females already roosting inside. Dillon follows her in. “Zzzzzzzzzz, zzzzzzzz, zzzzzzz,” he says as he herds them around until they form a tight cluster in one corner of the pouch. Scrunching down, he rubs secretions from a gland on his throat around the opening of his roosting pouch. Adding a drop of urine to the mixture, he creates his own special “perfume.” He's been marking his pouch in this way for several days now, even before any girls were roosting with him, He sings a little song as he rubs his throat against the pouch. “Chee chee chee chip, chee chee chee chip”
BCI members can read the whole story of the bat language research by Barbara French and Teh-Sheng Ma in the Fall issue of BATS magazine.
