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Great Tit Birds are Carnivorous
They are feeding on hibernating bats when other food is scarce in the winter
After I discovered a great tit chick directly outside of my window, I read their Wikipedia article and stumbled upon a curious fact in their diet. Alongside their normal food consisting of insects, seeds, and berries, they also feed on hibernating bats. In disbelief that these cute and tiny songbirds would kill other animals, I followed the source and found a paper about a 2009 Hungarian study. They not only observed great tits going after the bats but also conducted a few experiments to research this behavior further.
Bat Hunting
After previous reports about great tits going after bats in a Hungarian cave, the researchers conducted a more longterm observation study. Over two winters they repeatedly went out to the cave to observe the behavior of the great tits. On 22 observation days in a total of 45 hours, they recorded 18 successful bat kills by a great tit. They would fly slowly along the ceiling and walls searching through the little crevasses in the rocks where the bats are hibernating. Then the would land and kill the bat and either feed on it in place or even carry it out of the cave in their beaks. The bats are picked clean, therefore they go after them as a food source instead of competition for nesting grounds. Besides the directly recorded events, the researchers also found more bat carcasses when they arrived at the cave.
Food Scarcity
After they found that the great tits systematically go after the bats as an easy foraging food source in the winter, the researchers conducted an experiment where they provided plenty of food to the great tits and observed the bat hunting. Out of the 18 recorded bat kills, 17 of them happened on days where no food was provided, while only a single bat was killed on the days with access to easy food. This clearly shows that the great tits only go after the bats when there are no alternatives, so they might be nice birds after all. Even though I would never harm an animal, I would probably hunt a rabbit before I would starve in the forest, so who can blame the great tits.
