When a small bat hits a large bat, who is the bully?

One morning in the Panamanian jungle, a small fruit bat measured its competition. The odds didn’t seem to be in his favor.

The winged mammal, a short-tailed bat from Seba, weighed about half an ounce. But his six opponents, fringed-lipped bats, weighed twice as much and occupied the corner surrounded where the little bat wanted to rest. Even worse, larger bats are known to feed on small animals, such as frogs, katydids, and smaller bats, including Seba’s short-tailed bats.

None of this baffled the short-tailed bat of the Seba, which proceeded to scream, flutter its wings, and throw its body against the group of larger bats, striking one in the face more than 50 times.

“I’ve never seen anything like it,” said Ahana Aurora Fernandez, a behavioral biologist at the Berlin Museum of Natural History, who saw a recording of bats but was not involved in the research that produced it. “It’s a six-on-one bat,” Dr. Fernandez said. “Show no fear.”

The small bat’s belligerence paid off when the big bats fled. In the corner, the short-tailed bat of the Seba entered, which was joined a minute later by his companion, who had watched indifferently the fight closely.

Mariana Muñoz-Romo, a biologist at the Smithsonian Tropical Research Institute, and her colleagues observed this funny-sized fight and two incidents of harassment of similar bats in other bedrooms, which had been monitoring sexual preferences. of the larger-lipped bats. In a March issue of Behavior magazine, they asked how often small bats antagonize older bats. When there is a risk of eating, why choose a fight?

The researchers originally set out to study fringed-lipped bats, which were recently found to be smearing a sticky, fragrant substance on their arms, potentially to attract their mates. The animals also have an impressive appetite and have been observed eating important frogs.

“Sometimes they take a nap with the frog hanging from their mouths and then they wake up and keep eating,” said Rachel Page, a staff scientist at the Smithsonian Tropical Research Institute and author of the article.

Fringed-lipped bats have never been observed eating Seba’s short-tailed bat. But a previous report of an abandoned house overrun by fringed-lipped bats pointed to the skeletal remains of Seba’s short-tailed bats on the ground floor, Dr. Muñoz-Romo said.

Seba 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 rest in protected craters on the roofs of tropical caves. “Groups usually live in these holes,” said Dr. Sagot, who did not participate in the new study. “They generally struggle to get a good position in those holes.” Males also struggle to defend their harem from female companions of other males, he added.

Male Seba short-tailed bats have a repertoire of maneuvers climbed along their wings. First, they vocalize or shake them, trying to intimidate others from a distance. They then slap the other bats in the face with the tip of their wings, throwing their bodies and biting, the same tactics that the short-tailed bat of Seba used against his opponents with his marginal lips. The authors hypothesize that this innate aggression may have led the bat to attack its older neighbors to defend its mate.

Another issue refers to the bat fighting prize: a corner in the concrete plaza where the researchers were studying them. “You have four corners inside,” Dr. Muñoz-Romo said. “Why this corner if you have three more inside?”

Perhaps the microclimate of the coveted corner made it hotter or darker or more protected, the researchers hypothesized. “We look forward to what makes a bedroom attractive to bats,” Dr. Fernandez said, adding that they often do not accept artificial bedrooms.

The authors’ latest hypothesis speculates that Seba’s short-tailed bat may have launched a pre-emptive strike. “Maybe these guys were being so fighting that they said, ‘Don’t even hook us. We will not be an easy prey for you, “said Dr. Page.

Researchers hope to understand whether many Seba short-tailed bats choose these fights or whether there are only a few aggressive males, said Dr. Page.

Although the video makes the Seba’s short-tailed bat “absolutely annoying” and the fringed-lipped bats “super quiet,” Dr. Muñoz-Romo speculated that a previously unseen dynamic could give the younger aggressor a reason for his anger. Perhaps Seba’s short-tailed bats rested first in the corner, before the larger fringed-lipped bats took over.

“Who comes first?” she asked. “Who is displacing whom?”

The short-tailed bat of the Seba was not in imminent danger of being devoured thanks to the excellent moment of its crusade: it was 10 o’clock in the morning, and the predatory bats had returned from a night of partying, though maybe he didn’t know.

“Imagine you have to eat a large pizza after eating it all for hours,” Dr. Muñoz-Romo said.

Saved by the full bellies of his enemies, the little bat prepared and fell asleep quickly, resting his wings for when he had to slap again.

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