The African Harrier Hawk or Gymnogene (Polyboroides typus) and its dubiously separable conspecific the Madagascar Harrier Hawk (P. radiatus) are uniquely adapted raptors. Recent DNA work has placed the Harrier Hawks close to the Lammergeyer arguably making the term “Bearded Vulture” a double misnomer. Unrelated is the South American Crane Hawk (Geranospiza caerulescens) that copies in virtually every respect the anatomical details and habits of the Harrier Hawk and perhaps one day genetic studies may reveal a relationship. I have been lucky in being familiar with all three species in situ and in having rehabilitated a number of “Jim or Jeans” as we fondly call them.
It remains fairly common in urban and rural landscapes nesting in tall exotics quietly and drifting forth on huge wings and tails, mobbed by all birds… for it is a well-known robber of nests. Less well known is its rodent, bat and lizard and insect preference.
It has the famous backwards bending “knee” (actually its ankle) that allows the foot to be put down holes…away from the head. The foot and tarsus is laterally compressed, so much so that conventional jesses often fall off. The wrist is as thin as the entire foot, for even the toes and talons interlock into a seamless elongated pincer. Wherever it's foot is pushed, it can extract it whereas a normal raptor foot would lock the clenched foot as it retreated. The bill and head too are as thin as can be to follow the foot down holes, and the naked face is an obvious adaptation to stop feathers from abrasion. Why its wings are so huge is an open question for it weighs only about half a kilo. It eats little and flies far.
Its hunting strategy depends upon thorough observation and knowledge of animal behaviour. It must see from a distance small animals and birds entering holes and nests and fly towards unseen prey and extract it by hearing and “feel” alone. This suggests a high intelligence. They can clamber vertically up trees and cliffs, hanging and flopping about and using their bills and wings to gain purchase.
We have had many Harrier Hawks in for rehab, and trained one over 30 years ago for a BBC documentary on Bee-eaters (called “The Bee Team”) to act out this behaviour. They are constantly curious and must be given toys. They delight in having to find their food and testing them by hiding food down old gum boots makes them very happy. Their double jointed legs do not entirely conform to the books and in brief the bird can voluntarily extend its leg to just beyond straight while still able to clench its toes. When moved to some 15 degrees “backwards” the joint is at its limit and foot clenching ability is very limited.
Witnessing hunting behaviour
While in Tsavo West recently I was fortunate to take these photos of a Harrier Hawk catching a dormouse inside a Red billed Buffalo Weaver nest.
And previously I was able to photograph the leg at work in a “cut away” of a log, this time taking a gecko in Naivasha.
Rescue and release
An immature Harrier Hawk had fallen out of its nest in Thika and was rescued by Darcy Ogada. It recuperated for two months at Naivasha Raptor Centre where it builded up its strength before being released by Simon on Soysambu Conservancy on the 19th of March.
The first video shows the anatomy of an African Harrier Hawk's legs, with special joints making it long and straight for reaching into narrow spaces. This makes it impossible to secure a ring for future ID purposes. The second video of the bird's release shows the huge wing area for such a light nimble bird.
Kenya Bird of Prey Trust
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