This is a story about bats, and it solves a quarter-century-long mystery. In fact, since the early 2000s, Dr. Carlos Ibáñez of the Doñana Biological Station in Seville has maintained that some bats, to be precise the giant noctules, do not only feed on insects and other small “classic” prey, but also include certain birds in their menu.
Ibáñez is convinced of this after having observed, 25 years ago, bird remains in the feces of bats at his biological station, and now his intuition is corroborated by a study published in Sciencein which the zoologist and his team describe an audio recording that proves beyond a shadow of a doubt that giant noctules (also) eat birds.
Three clues prove it. Ibáñez’s idea, inspired by the poop of some bats, found further confirmation over the years when the zoologist found, on the ground under the noctule hunting areas, several bird wings torn from their owner: he was therefore convinced that these bats capture birds on the fly and tear off their wings to transport them more comfortably.
All these clues convinced him to set up a complex monitoring system for the giant bats at the Doñana Biological Station, a combination of surveillance cameras, military radars and ultrasonic recorders placed on the shoulders of the bats themselves using tiny backpacks. These tools in particular proved crucial for the latest study, which recorded two different hunting episodes involving a noctule and a robin. In one of these two episodes, the bat managed to capture its prey.
Like in a horror movie. The recording tells of a prolonged hunt. The noctule flew up to an altitude of 1.2 km, and here he met his prey: a robin who only noticed his presence at the last minute. However, he managed to evade the first capture attempt, launching into an escape that lasted more than a kilometre, during which the robin made 21 “requests for help” (which remained unanswered). The bat managed to capture the bird when the two were a few meters from the ground: at that point, the recording changes, and after the robin’s last desperate call what we hear are 23 minutes of chewing noises – the noctule consuming its meal, without ever stopping flying.
The diet of bats. In addition to finally proving Ibáñez’s theories right, this recording documents for the first time a very important fact: bats, at least the larger ones, do not only eat insects, and when the paths of migratory birds overlap with their hunting territory they willingly take advantage of it. Now it will be interesting to find out what other bats have birds in their menu.
