WEIRD NEWS

Praying Mantises Are Killing Birds And Eating Their Brains Worldwide

Mostly hummingbirds, based on the documented cases.

08/07/2017 14:49 -03

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.

Tom Vaughan via University of Basel
A mantis eats a black-chinned hummingbird in Colorado.

Retired ecologist Dietrich Mebs also provided some color about the process.

“They just hold [their prey], and they eat them while they are still alive, slowly and slowly until there is nothing left,” he told Newsweek.

Great!

So how did the zoologists determine this is a worldwide phenomenon? Live Science explains that researchers pored through records — including published studies, academic papers and even social media posts — to find records of mantises capturing birds. In all, they found 147 documented cases, spanning 13 countries. The earliest case they include was from 1864, but 67 percent of the cases were between 2000 and 2015.

Since they were relying only on cases documented by humans, it was tough to determine exactly how often mantises eat birds. But the researchers’ most relevant finding was that mantises engage in the behavior all over the world.

Randy Anderson via University of Basel
A mantis hunts down a ruby-throated hummingbird.

The most frequently documented victims of the mantises were ruby-throated hummingbirds in the United States. More than 70 percent of the cases found were mantises eating hummingbirds in the U.S., often when the birds were visiting hummingbird feeders or home gardens. (Since people often watch their feeders at home, it also makes sense people would be easily able to document these cases.)

In their press release, researchers link the high proportion of hummingbird encounters to several non-native species of large mantises that people released across North America decades ago in an attempt at “pest control.” They note there are also native mantises that prey on birds.

A quick Google search shows plenty of people still release mantises in the hopes they’ll eat insects such as aphids and flies. The downside is that they also consume creatures people want to have around, like butterflies and, yes, sometimes hummingbirds.

“Our study shows the threat mantises pose to some bird populations,” Martin Nyffeler, the lead author of the study, said in a statement. “Thus, great caution is advised when releasing mantises for pest control.”