As we’ve discussed before, invertebrates eating vertebrates is just plain wrong. But back then, we didn’t even mention one of the worst offenders: praying mantises. According to science and social media, mantises all over the globe are in the habit of grabbing tasty birds right out of the sky!
“When a bird comes within strike distance, usually 5–10 cm (2-4 in), the [mantis] quickly strikes with its two raptorial front legs, while holding to its perch with its four other legs.”
That description comes from a new study that asks the question: Just how common is it for mantises to prey upon birds? After all, their usual meals consist of other bugs. Researchers from Switzerland and the United States scoured the scientific literature, as well as videos and images shared online, and found nearly 150 cases of mantis-on-bird predation from every continent except Antarctica (no mantises there).
It turns out bird-hunting mantids (that is, mantis species of the family Mantidae) are fairly common. The study found a dozen different mantis species hunting two dozen species of birds, and with startling efficiency. Nearly every bird caught by a mantis – and not freed by the human observers – was eaten.
“Birds still alive when in the grasp of a mantid were usually trying to escape by vigorous wing beating accompanied by distress calls,” reads the authors’ somewhat haunting account, “but they were able to escape through their own efforts in only three attacks.”
The avian victims included robins, warblers, flycatchers, thornbills, and nine different species of hummingbirds. And the mantids' tactics were sometimes … unsettling.
“In several cases,” the study describes, “a hole was chewed in the victim’s head through which its brains were extracted.”
Yikes!
Female mantises are known for their appetites, famous for devouring the males they mate with. Unsurprisingly, all of the mantises observed eating birds in this study were lethal ladies.
In two of the instances the researchers found, mantises ate their feathered food while at the same time mating with a male! Not only are these deadly insects adept at bird-catching, they’re multi-taskers!
The mantises are also opportunistic. One study from 2006 described the clever insects going after birds caught in otherwise-harmless mist nets. They described their gory observations: ‘‘The modus operandi of the mantis seems to be to approach the bird … and then enter the cranial cavity via one of the eyes, feeding on the brain tissues.”
Double yikes!
In roughly four out of five cases, the unfortunate birds were hummingbirds. Mantises are known to hang around hummingbird feeders in people’s gardens, and they’re doing more than just bird-watching. These cunning predators have been recorded eating hummingbirds in 26 out of the 50 United States, from coast to coast.
In typical scientific fashion, the descriptions of these attacks can be disturbingly detailed. One account from Texas reads: “After an hour of continued observation, a shrill squeak attracted my attention … a Carolina Mantid had clasped a first-year female Broad-tailed Hummingbird, which struggled for another minute before dying.” The writer finishes, “When I left the area an hour later the mantid was still clasping and feeding on the hummingbird.”
Why so many hummingbirds on the menu? For starters, they are tiny, often smaller than the mantises themselves, which can weigh up to 7 grams and grow 10 centimetres (4 inches) long! Mantises often go after large prey, including not only big bugs, but salamanders, frogs, snakes, and more. For predators that are used to hunting fast-flying insects or big-bodied vertebrates, hummingbirds aren’t much of a stretch.
Being small, hummingbirds are actually common prey for other small animals such as lizards, snakes, and even frogs. Mantises aren’t even the only spineless hunters to go after these birds; orb-weaving spiders have a taste for them as well.
These mantis records are also a bit biased – since so many of these attacks take place in gardens, they’re more likely to be noticed by an observant person. YouTube is full of examples of people catching these backyard assaults on camera.
But there’s another reason. The majority of these records come from the United States, where hummingbirds contend not only with garden-stalkers, but with unfamiliar species. A number of mantis species, including the commonly-seen European Mantis, were introduced to the country by accident or as a form of pest control.
Unfortunately, they’re controlling more than just pests. Almost 60% of the unlucky hummingbirds in this study were caught by non-native mantises. "Our study shows the threat mantises pose to some bird populations,” said Martin Nyfeller, one of the new study’s authors, in a press release. “Thus, great caution is advised when releasing mantises for pest control.”
But I shouldn’t leave you thinking mantises are only going after smaller prey. In one observed case, an intrepid mantis grabbed a Blue-headed Vireo, a bird which can weigh up to nearly 20 grams – perhaps three times the size of a large mantis – and “holding the bird with a firm grip, was attempting to chew on the bird’s wing” before observers rescued it!
Header image: Gustavo Fernando Durán
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