The secretary bird is probably Africa’s most unusual bird of prey. Size, fancy headdress and lanky legs aside, there’s also its habit of kick-hunting across the landscape – pausing every now and then to deliver a cranium-crushing blow to some small mammal or snake, before gobbling down its meal whole.
And now, thanks to researchers from the Royal Veterinary College and Royal Holloway, University of London, we know just how powerful the birds' lethal kicks can be.
"[These birds] look amazingly dinosaur-like; they strut through open plains ... looking down the whole time. They wait for a snake to be flushed out ahead of them – and then they suddenly run over and start to deliver the kick to the head," the university's Dr Steve Portugal tells BBC News.
To measure the force and speed of these ninja skills, the team turned to a secretary bird named Madeleine for help. A resident at the Hawk Conservancy Trust in Hampshire, Madeleine had already been trained to attack rubber snakes for visitor displays, so her kicks could easily be put to the test.
“A force plate, hidden under artificial grass, was placed in Madeleine’s aviary and the rubber snake was pulled across the force plate, so the impact from her kicks could be measured,” explains the Trust in a Facebook update. High-speed cameras recorded the action, allowing the researchers to analyse the footage afterwards.
Each of Madeleine’s strikes was measured for timing, speed and impact – and the results were pretty impressive. The force generated by the kicks was 195 Newtons, equivalent to five times the bird’s own body weight. That’s easily enough to kill prey in just a single blow.
And Madeleine’s speed was even more remarkable. “The time it took to kick the snake in the head was just 15 milliseconds,” says the Royal Veterinary College in a press release.
To put that into perspective, it takes you around 150 milliseconds to blink your eyes – in just a fraction of that time, Madeleine can easily incapacitate a deadly mamba. Given that snakes (often venomous ones) are among the secretary bird's favourite foods in the wild, this ability to strike quickly and with deadly force is essential for survival.
“These results highlight the incredible system that is the secretary bird’s hunting technique – immense force to kill [or] disable a venomous snake combined with surgical accuracy to catch a fast-moving invertebrate. It’s a biological marvel," says the Trust's Campbell Murn.
Of course, none of this is any good when there are thieving eagles lurking about:
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Top header image: Pim Stouten, Flickr
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