Local coastal resident Doug Kunhardt was on his property earlier this month when a Crowned Eagle (Stephanoaetus coronatus) caught his attention. A closer inspection revealed that the eagle had killed a vervet monkey (Cercopithecus pygerythrus). Is is not uncommon for the Crowned Eagle to prey on monkeys and they have developed a reputation for taking monkeys in their distribution from the tropical forests of Senegal southwards as far as George in the Western Cape.
These eagles are unobtrusive and sit and wait (as photographed above) for hours for animals to pass by. It is an aerial hunter from above and within the forest canopy. It uses its powerful talons (particularly large for its size) to paralyse and kill the animal after dropping down on it.
Other animals which form the bulk of the diet include Blue Duiker (very common in our coastal dune forests), young bushbuck (the heaviest record being a 30 kg ram), moles, dassies, guineafowl, leguaans and moles.
Crowned Eagles need to surprise monkeys if they are to catch them. If the monkeys are alerted to the eagle there is no chance of a kill.
Doug’s photographs clearly illustrate that the eagle started feeding on the right hind quarter after removing the entrails. Food supply is an important factor which will determine whether breeding takes place or not. This species mates for life and have a permanent nest in a large forest tree. The nest presents as a bulky platform of sticks and twigs placed in the fork of a tree. Breeding takes place between February and November. Favourite trees to nest in are the indigenous yellowwoods and the exotic eucalyptuses.
A few hours into the kill and the monkey has almost been completely devoured, save for skeletal bits and the head (as documented above). Interesting is that the Crowned Eagle normally flies off after disemboweling the prey and in this instance it seems to have fed on the ground.
Museum scientist, Kevin Cole, thanks Doug Kunhardt for documenting this natural history event and for submitting his photos for the record.
References: The birds around us by Richard Liversidge
The complete book of southern African birds compiled by P.J. Ginn, W.G. McIlleron and P. le S. Milstein