Vultures and other scavenging birds are adapted to the task of locating and feeding on the carcasses of large mammals. Most of these are animals that have died of natural causes but vultures also regularly eat the remains of predator kills. Due to the unpredictable nature of their food supply, they may fly great distances in their searching.
The large vultures are heavy birds and rely on air currents and thermals to remain airborne. They soar to great heights, scanning the ground for food and watch the movements of other scavenging birds below. The lighter Bateleur, Tawny Eagle, kites and crows are able to fly at lower altitudes and, since they are independent of thermals, are up-and-about earlier in the morning. It is these birds that often first find a carcass and the vultures watch their movements carefully.
When perched in trees around a carcass, vultures are extremely cautious and often wait for an eagle or crow to land and feed first. Once sure that all is safe, the vultures will descend on the carcass, fighting amongst themselves to reach the food. A group of 50 vultures is able to reduce the carcass of a sheep or impala to skin and bones within twenty minutes.
Reports of vultures preying upon domestic stock have been reported sporadically over the years. Few events have ever been properly documented, however, and in the cases where the facts have been followed up, a misinterpretation of the events has invariably led to the report. Vultures are specialised scavengers and seldom kill prey.
As can be seen from the illustration below, vultures are not adapted for killing. having weak feet, and being extremely cautious about approaching even a dead beast
Vultures are usually monogamous (ie, each sex has only one dedicated partner) with a long term pair-bond, and are territorial around the nest site. The stick-platform nests are often reused annually.
Vultures only lay one egg and do not necessarily breed annually. Factors which may influence whether vultures breed or not are :
The physical condition of the pair. If the pair has not had enough food, the female will not lay an egg. This is determined by the food supply available before the breeding season, which starts in winter.
Human disturbance while nest-building, in the egg-laying stage or while incubating can lead to desertion of the nest
After the nest is built and the egg is laid, the incubation period is close to 2 months. The nestling is then dependent on its parents for four months. Once the chick leaves the nest, it still relies on the parents to educate it, which can take up to a further 6 months.
A threat to the chick is that parents can injure their young developing chick by trampling on it, leading to the chick not surviving. Chicks are also preyed on by man, predatory mammals and other raptors
Vultures can not vary their reproductive rate to suit environmental factors. Hence, as the reproductive cycle lasts approximately 12 months, and the fact that vultures are monogamous, fatalities can have a profound impact on populations.
The record for longevity in Lappet-faced Vultures is a bird which was ringed (G19378) by Dr Pat Benson as a nestling on the 23rd October 1992 near to Shingwedzi Camp in Kruger NP, and was photographed (ring number read from picture) by Coen van den Berg at Sable Dam in KNP. This longevity of nearly 24 years is similar to that of Roberts' 23 years for a captive bird