It sounds like the stuff of nightmares: a string of boa constrictors hanging from the mouth of a cave snatching bats out of midair as they leave and return to their roosts. But this exact behavior has been spotted in Cuba, and is remarkable not so much because of the method of the hunt but of the coordination of the hunters.
According to Vladimir Dinets, a research assistant professor of psychology at the University of Tennessee, Knoxville, only a small percentage of snakes has ever been seen to hunt in coordination with their brethren. For the most part, the reptiles are considered solitary hunters. So when Dinets observed Cuban boas – the largest native terrestrial predator in the country – hanging from cave mouths to grab bat-based breakfasts and dinners, he investigated further.
Dinets, who has reported his study in the journal Animal Behavior and Cognition (PDF), found that whenever more than one snake was present in a cave mouth, the snakes would position themselves by hanging from crevices in the cave's ceiling in such a way as to improve the catching ability of all. The presence of more snakes lowered the catch time of the entire group and, what's more, snakes who hunted in a group always got their prey. Solitary boas, however, would often end up bat-less after their night of hunting. Each snake was found to take only one bat per hunt.
Overall, very little is known about snake-hunting behavior, so Dinets says the rare coordinated spectacle he observed might be more common than we think.
"It is possible that coordinated hunting is not uncommon among snakes, but it will take a lot of very patient field research to find out," he said. "This is the first scientifically documented case of coordinated hunting by snakes," he added in the paper. "It is also the first study on reptiles to statistically test for coordination between hunters and to show that coordination increases hunting success."
He also mentioned that, while it's rare to see snakes coordinating a hunt at all, the chance to see the Cuban boas doing their thing may get even slimmer as the animals continue to be hunted for food and possibly the exotic pet trade.
"I suspect that if their numbers in a cave fall, they can't hunt in groups anymore and might die out even if some of them don't get caught by hunters," Dinets said. "A few of these caves are in national parks, but there's a lot of poaching everywhere."