Vultures

Kruger National Park | February 2016

Vultures are some of Africa’s most iconic birds. They are also very important birds in that they play an ecological role in cleaning up the remains of animal carcasses that, if left to continue rotting, could lead to diseases being spread.

Unfortunately, vulture numbers all across the world are plummeting. “In the 1980s there were as many as 80 million white-rumped vultures (Gyps bengalensis) in India, when it was the most numerous species of raptor in the world. Today, however, its population is only in the thousands – the fastest population collapse of any bird species in recorded history, including the dodo.

Vultures previously played an important role in public sanitation in India. Their disappearance has resulted in an explosion of rats and feral domestic dogs; the spread of diseases including anthrax, rabies, and plague; a public health crisis; and a total cost of up to 34 billion US dollars (as of 2015)” – Wikipedia.

This population plummet was as a direct result of using an insecticide called Diclofenac on cattle to try and get rid of ticks and external parasites. Vultures feeding on carcasses of animals that had been dipped in Diclofenac were killed off rapidly.

In Africa the main causes of the decline in vulture numbers are habitat destruction, lack of food (due to there being smaller and smaller wild areas – in built-up areas carcasses are usually disposed of before the vultures can get to them), use of vulture body parts in traditional medicine and spells and recently the killing of vultures by poachers. When a large animal such as a rhino or elephant dies large numbers of vultures gather to feed on the carcass. Game wardens and game-rangers often notice the gatherings of vultures and inspect the cause of the grouping. This enables them to find the poached animals quicker and they can start tracking down the culprits much faster. The poachers have realized this and have started to poison the carcasses after they have removed the horns or ivory, in order to kill off the vultures. This has led to the demise of many hundreds of vultures. In one such elephant poaching incident, near the Caprivi Strip in northern Namibia, over 600 individual vulture carcasses were found. Another incident recently occurred in the Kruger National Park where over 100 vultures were found dead, nearby the poisoned carcass of an elephant.

Vultures are slow breeders, and usually only have one chick at a time, and therefore populations recover very slowly after catastrophes like these. Furthermore, vultures travel extremely long distances in order to find food. It was reported that a young Cape vulture fitted with a tracking device in Namibia flew across six countries in southern Africa and covered at least 64 000 kilometres. Poisoning incidents such as the ones described above therefore do not only affect the local population of vultures but also affect the vulture population right across Africa. A poaching incident killing numerous vultures in South Africa will therefore also affect the numbers of vultures in neighbouring countries.

Fortunately here at Singita Lebombo and Sweni we still see fairly large numbers of vultures. The five main species of vultures that we see in the area are, in order of size, lappetfaced vulture (Torgos tracheliotos) with a wing-span of up to 2.8 metres, Cape vulture (Gyps coprotheres), whitebacked vulture (Gyps africanus), white-headed vulture (Trigonoceps occipitalis) and hooded vulture (Necrosyrtes monachus).

The International Union for the Conservation of Nature (IUCN) recently listed the white-backed vulture, the white-headed vulture and the hooded vulture as Critically Endangered Species, while the lappet-faced vulture and the Cape vulture are listed as Endangered Species.

Due to the drought that we are presently experiencing in the area there have been quite a few mortalities of buffalos and hippos. This has given us some great vulture viewing opportunities. It is an amazing sight to come around the corner and find a dead tree covered with vultures, like spectators at a major sports event or like a Christmas tree covered in decorations. Upon approaching the area the guests are often over-awed by the hissing, squealing, heaving, squabbling mass of birds that gather to feed on these large carcasses. At some of the carcasses we have literally seen hundreds of birds fighting to get some of the meat. It is one of the most amazing sights to see the sudden descent of masses of vultures onto a carcass and then the arguing and fighting that goes on in order to get a space where each can feed.

Although vultures can fly very high (a Rüppell’s vulture was recorded to have been sucked into an aircraft engine off West Africa at an altitude of more than 11 300 metres) and have extremely good eyesight (it is estimated that vultures eyesight is up to eight times better than that of humans), they are often not the first birds to appear at carcasses. Usually it is the lower-flying raptors that such as tawny eagles and bateleurs that discover the dead animals first.

Most vultures, due to their large size and heavy weight (lappet-faced vultures can weigh up to 13.5 kilograms), do not start flying until later in the morning when the sun has already heated up the earth causing thermals (hot air pockets) to rise, which aid the vultures in attaining height without having to exert excessive amounts of energy.

Once the vultures are in the air they are not only looking for dead animals to feed on or predators that they can follow, but rather they are watching the other vultures and birds of prey.

White-backed vultures (the most common vultures in the area) are more intent on watching the antics of other vultures than they are on sighting a kill themselves. The first vulture to descend starts a chain reaction: those closest to it are the first to make a move, dropping out of the sky with amazing speed, and others further away follow suit. Several hundred of the scavengers have been recorded descending onto a carcass in less than an hour and from distances estimated as far as 35 kilometres away. They need to drop quickly in order to be able to compete with other vultures for a space at the carcass. This can lead to some heated arguments…

It may look chaotic to the guests, but there is a hierarchical system of feeding amongst the different species of vultures. The hooded vultures are often the first to descend on a kill (due to the fact that they are smaller than the other species and can therefore start flying earlier than the others). Unfortunately for them they have a weak, thin beak that is more suited to picking up small pieces of meat that the other vultures cannot get to (e.g. the muscles between the ribs and in inaccessible places). They therefore often just manage to peck out the eyes and get at the softer parts of the carcass. They then need to wait for either the large vultures such as the lappet-faced vultures or other scavengers such as hyenas or jackals to open up the carcass. White-backed vultures are often the next vultures to appear, but they also need to wait for the carcass to be opened up (particularly if it is a thick-skinned animal such as a buffalo, elephant, rhino or hippo). They thus, often just perch in the trees waiting for the carcass to be opened. The vulture that is most suited to ripping open carcasses is the lappet-faced vulture. They are also the largest of the five species and therefore dominate the carcass, taking the best pieces for themselves. The white-backed vultures are the most numerous. They are frantic, noisy feeders, hissing and mobbing one another to get
their share of the spoils. They will feed inside a carcass, sheering meat from bones with their powerful bills.

The more solitary white-headed vulture generally remains to one side of the feeding activity, taking bits of meat and feeding some distance away. Once the larger vultures are finished feeding the hooded vultures once again come to the carcass and feed off the scraps and smaller pieces of meat that the other vultures could not get to. Large numbers of vultures can literally reduce a carcass to a skeleton in a matter of minutes.

Image: Cape vulture – photo by Margaux Le Roux, Lappet-faced vulture – photo by Deirdre Opie, Hooded, Cape and white-backed vultures – photo by Brian Rode, and White-headed vulture – photo by Brian Rode.