Mostly hummingbirds, based on the documented cases.
Nature is beautiful, but it can be kind of messed up.
As an illustration, we’ll refer you to a press release this week from Switzerland’s University of Basel, titled “Praying Mantises Hunt Down Birds Worldwide.” Carnivorous mantises feed most frequently on insects or spiders, but zoologists from Switzerland and the United States have published research indicating that mantises also kill and devour small birds on all the continents except Antarctica.
For those unaware that praying mantises eat small birds, this news is surely alarming. But honestly, the title of the press release doesn’t convey the true horror of the situation.
Newsweek did some additional reporting, interviewing two scientists (unaffiliated with the research) who told them about the method mantises typically employ in their avian consumption.
The mantises usually “pierce the skull to feed on brain tissue,” said biologist William Brown of the State University of New York at Fredonia.