One morning in the Panamanian rainforest, a small fruit bat increased its competition. The odds did not seem to be in his favor.
The winged mammal, a Sebas short-tailed bat, weighed about half an ounce. But his six opponents, bats with fringe lips, were twice as heavy and occupied the encased corner where the little bat would lie. Even worse, the larger bats are known to enjoy small animals, such as frogs, cathedids and smaller bats – including Seba’s short-tailed bats.
None of this surprised Seba’s short-tailed bat, which continued to scream, shake its wings and throw its body against larger bats, hitting one in the face more than 50 times.
“I have never seen anything like it,” said Ahana Aurora Fernandez, a behavioral biologist at the Natural History Museum, Berlin, who saw a recording of the bats but was not involved in the research that produced it. “It’s a bat against six,” said Dr. Fernandez. “He shows no fear at all.”
The warfare of the little bats paid off when the big bats fled. The corner cleared, Seba’s short-tailed bat moved in, a minute later joining his female companion, who had casually watched the match from up close.
This funny-sized fight and two similar incidents of bat bullying in other sleeping quarters were observed by Mariana Muñoz-Romo, a biologist at the Smithsonian Tropical Research Institute, and her colleagues who had monitored the sexual preferences of the larger bats with fringe lips. In a paper published in March in the journal Behavior, they asked how often small bats counteract larger ones. When it comes to a risk of being eaten, why choose a match?
The researchers initially set out to study bats with fringe lips, which were recently discovered to smear a sticky, fragrant substance on their arms, potentially to attract mates. The animals also have impressive appetites and have been observed eating large frogs.
“Sometimes they take a nap with the frog hanging out of their mouth, and then they will wake up and continue eating,” said Rachel Page, a staff researcher at the Smithsonian Tropical Research Institute and author of the paper.
The fringed bats have never been observed eating a Sebas short-tailed bat. But an earlier report of an abandoned house being overtaken by bats with fringe lips noted the skeletal remains of Seba’s short-tailed bats on the ground below, Drs. Muñoz-Romo.
Seba’s short-tailed bats are common in Central and South America. The small size of the males does not prevent them from being aggressive. Maria Sagot, a behavioral ecologist at SUNY Oswego, said bats prefer to roost in sheltered craters in the ceilings of tropical caves. “Groups usually live in those holes,” said Dr. Sagot, who was not involved in the new investigation. “They tend to struggle to get a good position in those holes.” The males also struggle to defend their harem of female mates from other males, she added.
The male Seba’s short-tailed bat has a repertoire of escalating maneuvers along their wings. First, they vocalize or shake them and try to intimidate others at a distance. Then they hit the other bats in the face with their wingtips, slinging their bodies and biting – the same tactic that Seba’s short-tailed bats used against their fringed opponents. The authors assume that this innate aggression may have caused the little bat to attack its larger neighbors to defend its female companion.
Another question concerns the price of the bat fight: A corner in the square concrete hut where the researchers studied them. “You have four corners inside,” said Dr. Muñoz-Romo. “Why that corner if you have three others inside?”
Perhaps the microclimate in the coveted corner has made it more sluggish or darker or more sheltered, the researchers assume. “We wonder a lot about what makes a chicken coop attractive to bats,” said Dr. Fernandez and added that they often do not accept artificial chickens.
The authors’ latest hypothesis speculates that Seba’s short-tailed bat may have launched a preemptive strike. “Maybe these guys were just so eager to say, ‘You don’t even have to pick on us. We’re not going to be an easy prey for you,’ said Dr. Page.
The researchers hope to understand if many of Seba’s short-tailed bats choose these fights, or if there are only a few aggressive males, said Dr. Page.
Although the video makes Seba’s short – tailed bats “absolutely annoying” and bats with fringed lips “super peaceful”, Dr. Muñoz-Romo in that previously unseen dynamics could give the lesser aggressor a reason for his rage. Perhaps Seba’s short-tailed bats rested first in the corner before the larger fringed lip bats took over.
“Who is the one who comes first?” she asked. “Who displaces whom?”
Seba’s short-tailed bat was not in imminent danger of being devoured thanks to the excellent timing of his crusade: it was 10 o’clock in the morning and the predatory bats had returned from a night of feasting, though he may not have known it.
“Imagine having to eat a big pizza after you’ve already eaten everything for hours,” said Dr. Muñoz-Romo.
Rescued from the full stomachs of his enemies, the little bat cared for itself and immediately dozed off and rested its wings, for when he should need to strike again.