The Bird That Packs A Punch
Across the African Savannahs many different birds can be seen strutting around on long legs, a perfect adaptation, often coupled with long necks, to give them a higher vantage point to see over the long grasses. We are talking about ostrich, korhaan, ground hornbill and storks to name a few. All these birds use the same method of steadily walking through the grass picking of preferred prey items; grass itself in the case of the ostrich.
One of the most fascinating to me is the secretarybird (Sagittarius serpentarius). Reportedly named for its resemblance to a medieval scribe with a quill behind his ear other sources suggest the name is a Francophile corruption of the Arab word saqr et-tair which translates to hunter-bird. Whatever the origins of its name the frond of spatulate nape feathers and the elongated central tail feathers easily distinguish this bird.
It is something of an enigma taxonomically speaking, making up its own unique family, Sagittariidae. It seems secretarybirds are related to eagles sharing skull structure and a type of feather lice. Currently aligned to diurnal birds of prey it has previously been thought of as a relative of storks and cranes. Indeed its breeding behaviour is very similar to that of storks, which to make things more complicated are also share a close affinity to birds of prey.
Taxonomic complexities aside secretarybirds do look like elongated hawks, they share that hooked bill and yellow cere common in birds of prey, they also possess a large gape which allows them to open the bill wide enough to swallow large prey whole. But it’s their feet that do all the work.
The modus operandi for a secretary bird is to stalk along quietly and stomp its prey with a torrent of fast powerful kicks to dispatch it. This method is used for a number of prey items such as arthropods, rodents, amphibians, game birds even mongooses. In fact anything, really, that can be subdued and killed by its deadly kicks is fair game. That said it is the secretarybird’s ability to despatch snakes that has endeared it to most Africans.
To sneak up on a snake and then kill it quickly takes a lot of skill and you best not make a mistake otherwise in the African bush you may end up the one dying.
A study led by Dr. Steven Portugal, from Royal Holloway, University of London found that although other birds of prey strike their prey with far more force this is enhanced by the momentum of their entire bodies plunging down from flight. The secretarybird is able to exert a force 5 times greater than its own body weight from standstill and can repeat this accurately with multiple kicks being delivered at a speed of 15 milliseconds each. Fast and furious, that’s how this bird tackles deadly snakes and biting mongoose.
If you are interested you can read the paper here. http://www.sciencedirect.com/science/article/pii/S0960982215014839