Péter Estók of the Max-Planck-Institute for Ornithology, Germany, first saw a bat being captured by a tit in a Hungarian cave in 1996. Ten years later, he and fellow bat ecologist Björn Siemers recorded 18 examples of pipistrelle bat predation by great tits, over the course of two winters in the same cave in the Bükk Mountains.
Bat hunting
The birds seek out bats as they wake from hibernation and usually eat them in the cave, though sometimes they carry them to a nearby tree.”The birds don’t kill the bats before they start eating them,” says Siemers, “but the bats eventually die when the birds peck open their brain case.”
As the bats are still very cold, only a degree above ambient temperature, they are extremely slow and easy for the birds to subdue. Nevertheless, it is a considerable feat for the tits given that a pipistrelle weighs approximately 5 grams and a great tit only four times as much.