Hummingbirds beware: Study documents praying mantises killing, eating birds

They blend in with their leafy surroundings, strike with lightning speed and eat the brains of small birds and they're only about nine centimetres long.

Researchers from the University ofBaselhavedocumenteddozens of cases, over nearly 100 years, of praying mantises feeding on small birds. And while they're not fussy eaters, they seem to be partial to hummingbirds.

The cases span 13 countries including Canada and have occurred on allcontinentsexcept Antarctica.

The researchers scouredvarious sources, obtaining their data from reports on bird predation by online sources, as well as Thomson-Reuters archivesand peer-reviewed literature.

In all, they found 147 reports of praying mantises trying to prey upon smaller birds. They found that 12different species of mantids killed and ate 24 different species of birds, including sevenspeciesof hummingbirds.

The new findings, published in the Wilson Journal of Ornithology,paintan even moreghastly picture of the praying mantis aninsectbest known for the fact that the females kill their partners after mating.

The researchers can't say whether this behaviour is on the rise, but they do think people are partly to blame.

That's because we attract hummingbirds to gardens by planting the nectar sources they seek, and at the same time release mantids such as the praying mantis into gardens for pest control.

"Thus, humans bring these two together in an unnatural manner," MartinNyffeler,co-author of the paper and and professor of zoology at the University ofBasel, told CBC News in an email.

Diet of the mantis

As for what the praying mantises were consuming of the birds, it was a bit gruesome.

"About two-thirds of the birds were bitten into the head, neck or throat. In several cases, a mantid had chewed a hole in the victim's head and was extracting its brains," Nyffelersaid. "Occasionally birds were scalped or decapitated, and in some cases they were de-feathered by their captors."

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Sometimes, the entire bird was consumed, while other timesit was a small portion likely dependant on how hungry the mantis was,Nyffelersaid.

There has only been one documented case in Canada in the Hamilton, Ont., area.

Praying mantises usually feed on insects like butterflies, honey bees, flies and spiders. Occasionallythey've been found to feed on small vertebrates, such asfrogs, lizardsand snakes.The researchers don't know why some have been found to feed on small birds.

Waiting game

Mantidstypically ambush their prey: camouflaged byfoliage, they strike out and grasp their unsuspectingmeal with their twofront legs, while holding onto a leaf or grass with their four back legs. Then, while their food is still alive, theybegin their feast. There is no poison involved.

The researchers are fairly certain the mantids are killing the prey and not just scavenging.

It is the nature ofmantidsto eat live prey, noted Nyffeler, citingstudyco-author and mantis ecologist Mike Maxwell.

"Furthermore, it has been observed many times how mantids were hunting down birds, or humans encountered a mantis holding a live bird in its claws," Nyffeler said.

Nyffeler said that anyone who sees a bird trapped by a mantidcan try to safely separate the two and then take the mantid to a place with fewer birds.

In all, Nyffeler, is impressed by what the study has shown.

"The fact that eating of birds by praying mantises is so widespread, both taxonomically as well as geographically speaking, in my opinion is a spectacular discovery,"Nyffelersaid.