Secretary Birds Stamp On Their Prey With Force 5 Times Their Weight – New Study

MessageToEagle.com – Snake-hunting Secretary Birds use the force of five times their body weight to stamp on and kill their prey, according to a new study conducted by researchers from Royal Holloway, University of London, the Royal Veterinary College and the Hawk Conservancy Trust.

The contact time between the bird’s feet and the snake is delivered extremely quickly — on average just 15 milliseconds, researchers say, who tested a captive secretary bird called Madeleine.

Madeleine was trained to attack a rubber snake to demonstrate the hunting techniques of this type of bird. The scientists measured Madeleine’s kicks by putting a force plate (hidden under artificial grass) in the bird’s enclosure and pulling the rubber snake across the force plate.

As Secretary Birds hunt venomous snakes, a missed strike could have deadly consequences so the birds are capable of delivering fast, forceful and accurate foot strikes that are sufficient to stun and kill prey.

Dr Steve Portugal from the School of Biological Sciences at Royal Holloway, University of London, said:

“The exceptionally rapid strike contact duration is 1/10th of the time it takes to blink an eye — which takes around 150 ms.

“Such rapid time, coupled with the exceptionally long legs, means the birds can’t be using proprioreception — the sixth sense we use to sense our position and movement.

“Therefore, they are using visual targeting and feed-forward motor control — (pre-planned movements) — during strike events. This means the birds can only correct for a missed strike in the next kick — once they’ve started a kick, they can’t adapt it, and they have to wait for the next strike.”

Dr Monica Daley, a Senior Lecturer at the Royal Veterinary College explains:

“There are interesting potential technological applications in ‘biologically inspired’ control of exceptionally fast movement in robots and prosthetics.”

“A comparable task might be playing baseball with a prosthetic arm, which requires very fast, forceful and accurate arm movements for pitching and batting.”

Dr Daley, adds: “Despite their very unusual appearance with exceptionally long legs, the secretary bird’s striding gait is remarkably similar to of ground birds such as pheasants, turkeys and ostriches.”

The study, published in the journal Current Biology.

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source: University of Royal Holloway London