In December 2009 Dato’ Dr Amar-Singh HSS photographed an adult Brahminy Kite (Haliastur indus intermedius) near his Ipoh home in the Malaysian state of Perak. The kite was in an aerial battle with a Changeable Hawk Eagle (Spizaetus cirrhatus limnaeetus), the account of which has been posted earlier.
What attracted his attention was the right wing of the kite where a few flight feathers were missing. The left wing on the other hand had a complete set of flight feathers – see HERE where both wings are clearly shown.
According to field ornithologist Wang Luan Keng, the Brahminy Kite is undergoing asymmetrical moulting of the wing feathers. Normal moulting is more or less symmetrical, both wings shedding one feather at a time. The loss of two feathers in the right wing is most unusual. Most possibly fright or force moult came into play. Can it be that the kite lost the feathers in an earlier battle with the Changeable Hawk Eagle? The feathers could have been shed when it was attacked, as a defense to distract or confuse the attacker.
The fact that all the primaries and secondaries look new suggests that the kite is not undergoing normal moult, another argument to suggest fright moult.
“The feathers of the right wing were lost quite a while ago as the two new growing feathers are already a few cm long (feathers normally grow just a few mm a day),” adds Luan Keng. “So I can’t say if the feathers were lost due to fighting but they were lost accidentally (not due to regular moult) and because they are important flight feathers, the bird is growing them again.”