A new international study led by researchers from Aarhus University and the Smithsonian Tropical Research Institute (STRI) reveals that small bats can be just as efficient predators as lions – and often more successful.
To find out how fringe-lipped bats (Trachops cirrhosus), miniature carnivores from the forests of Panama, hunt in the wild, the research team equipped 20 of them with miniature "backpacks" – biologging tags that recorded every movement and sound, including those from the surrounding environment.
The data revealed something remarkable: these bats hunt large prey such as frogs, birds and small mammals, using a "hang-and-wait" strategy combined with an exceptionally sensitive sense of hearing that allows them to pick up sounds made by their prey. In this way, they can quickly locate large prey and strike with minimal effort.
The study, published in Current Biology, concludes that these bats can consume nearly their own body weight (30 grams) in a single meal, making them among the most energy-efficient predators on Earth.
A biological paradox
The team set out to solve a biological paradox:
In the animal kingdom, size usually shapes hunting strategy. Large predators such as lions and polar bears can afford to chase big, energy-rich prey because their large energy reserves and low metabolic rates let them outwait repeated failed hunts. Small predators, like rodents and most bats, face the opposite challenge. With tiny energy stores and high metabolic rates, they need to eat almost constantly and consequently target abundant, easy-to-catch prey to survive.
But a few bats break the rules. Nine known species are true carnivores, meeting more than half of their energy needs by eating vertebrates such as frogs, birds, and even small mammals. This raises an intriguing question: how can such small predators, with limited energy reserves and high daily demands, survive by hunting large and rare prey – a strategy that usually requires enormous effort and involves frequent failure?
To answer that question, the researchers used the fringe-lipped bat as their model species.
These bats are known to feed on small túngara frogs, and when they went hunting with the miniature backpacks attached, the researchers expected to see them catching large numbers of these small frogs.
Hunting like big cats
But the data told a completely different story. These small bats hunt more like big cats than like their fellow bats.
They lie (or rather hang) in wait to ambush their prey, strike with precision, take large victims, and rest for much of the night between hunts – just like lions and leopards.
The movement and sound data showed that the bats combine their "hang-and-wait" strategy with hearing, vision, and echolocation. They have low-frequency hearing and are already known to eavesdrop on frog mating calls. By combining these senses, they can detect and kill large prey with remarkable efficiency.
Big predators trapped in small bodies
"It was incredible to discover that these bats hunt like big predators trapped in tiny bodies," says lead author Leonie Baier, a Marie Skłodowska-Curie postdoctoral fellow at Aarhus University and research fellow at STRI. "Instead of spending the night constantly on the wing, they wait patiently, strike with high precision, and sometimes end up catching enormous, energy-rich prey. The discovery that an animal this small can do this really turned our assumptions upside down."
The recordings revealed that during the study period, the bats spent 89 percent of their time stationary, conserving energy. When they did attack, it happened quickly: most flights lasted less than three minutes, and the median hunting flight only eight seconds.
The bats succeeded in about 50 percent of their hunts – far more than large mammals, where lions, for example, succeed only 14 percent of the time. For polar bears, the rate is as low as two percent.
Eighty-four minutes of chewing
The prey also turned out to be larger than expected. On average, it weighed seven percent of the bat's own body weight – equivalent to a 70-kilogram person eating a five-kilogram meal.
In some cases, the bats caught prey nearly their own size, such as the large Rosenberg's gladiator tree frog, which can weigh up to 20 grams.
The size of the prey could be inferred from how long the bats could be heard chewing on it in the sound recordings – the longest meal lasted 84 minutes.
The older, the better
Older bats were found to handle larger prey suggesting that hunting skill improves with experience. The species is already known for remembering specific frog calls for years and for learning new hunting techniques by observing other bats.
"We wanted to understand what these bats are actually doing out there in the dark – so we listened in, much like the bats themselves listen to their prey," says Laura Stidsholt, assistant professor at Aarhus University and senior author of the study. "With the data from our biologging tags, which combine high-resolution sound recordings with movement data, we were able to reconstruct entire hunting sequences in the wild. In this way, we experienced the forest through the bats' ears – revealing a hidden world of patience, precision and survival in the dark."
