There are two groups of vultures in the world. The Old World vultures, with 16 species occurring in Africa, Europe and Asia; and the New World vultures with seven extant species, occurring in the Americas. Old World vultures are more closely related to eagles and hawks than to New World vultures; the similarities between them are due largely to convergent evolution. Convergent evolution is the process whereby species that are not closely related, independently evolve similar traits as a result of having to adapt to similar environmental conditions or ecological niches. Among the Old World vultures, the Bearded Gypaetus barbatus, Egyptian Neophron percnopterus and Palm-nut Vultures Gypohierax angolensis are more closely related to each other than to other vultures. Strangely, no vultures occur in Australia, but several species of crow and raven fulfill the role of scavengers there.
Vultures are often wrongly considered ugly and stinky, and given villainous roles in stories, movies and books. The thought of these birds feeding on dead and rotting things might not be a pleasant one, but, without them we would be in big trouble! Vultures are nature’s clean-up crew. They consume the remains of large mammals. Some of these killed by lions or other large predators; some die of disease, old age, starvation or other reasons. In all cases, vultures are the ones who end up cleaning the carcasses down to the bare bones – the Bearded Vulture or Lammergeyer Gypaetus barbatus consumes the bones too. If vultures weren’t around, rotting carcasses would pile up. Over days or weeks these piles of stinking, festering carrion will be wonderful incubators for all kinds of diseases and pollute water resources. The carcasses will still get scavenged, but at a much slower rate, by animals like jackals, rats, stray dogs, and flies. Some of these species are not always desirable to have around, and may, instead of limiting, contribute to the further spread of diseases, including to humans and domestic animals.
A study led by Anil Markandya looked at the impacts of the disappearance of vultures in India. Vultures die offs occurred because of a veterinary drug called diclofenac, used as a painkiller and anti-inflammatory for cattle. While it helped the cattle, it harmed the vultures. Cattle in India are mostly considered sacred; they are not eaten, but when they die, are left for the vultures to consume. The vultures consumed many carcasses that had diclofenac in their systems; and only a small amount of it in a vulture’s system is enough to give it kidney failure. Vulture populations declined catastrophically!
What was the effect of the vultures vanishing? The researchers concluded that the decline in vultures, which meant more and more carcasses, led to an increase in the stray dog population by as many as seven million individuals! As a result, there was a big increase in dog bites – Markandya and his team estimated an additional 40 million dog bites over a 14 year period. This meant an additional 40,000 human deaths due to rabies, India being particularly hard hit by this disease. Researchers estimated the cost to the Indian government and health services at 34 billion dollars!
The principle of this study illustrates is that the disappearance of vultures is something that costs us humans money. And this study looked at only one factor, namely, rabies. There are likely many other impacts, diseases that may affect humans as well as animals, that may increase if the amazing feathery “clean-up crew” are not there to do their job.
We humans tend to value money above all, it would seem, and sadly many people in power are hesitant to act on anything if it does not affect their bank account. But, there are many things on our wonderful planet that go beyond monetary value, many things that are priceless. It is not really possible to estimate the full value of something like vultures in terms of money. Yes, they help limit diseases in various ways. There certainly would be many more indirect ways in which vultures are protecting us and saving us money. But, they are just one part of the amazing web of nature, where millions of species are all interacting with each other and with the environment to form a stable, whole, harmonious, living system or biosphere. For our own comfort, and survival, it is vital that the whole of this ecological web on Earth should be protected. Any species we lose leaves a ‘gap’ in the network. While one species may step up to take over a role left behind by another species that has vanished, there is certainly a limit to the knocks that any ecosystem can take. And the same goes for the ecology of the Earth as a whole. We humans are dependent on the healthy functioning of the living Earth, the Earth is not dependent upon us. We need the Earth for our survival, but the Earth does not need us.
Beyond their value, there is the sheer wonder of vultures. They have amazing physiological adaptations suited to their role, some of which we have discovered only recently. They have very acidic gastric juices, helping to rapidly kill harmful bacteria in the meat they eat. Other bacteria they tolerate, these flourishing in their guts and even helping them digest their food. They have very powerful immune systems, with copious anti-bodies in their blood. It is ironic that they can consume vast amounts of contaminated carrion with no ill effect, but are so vulnerable to the veterinary medications used to treat livestock.
Lappet-faced Vulture (left) and Hooded Vulture (right)
New World vultures have an extremely keen sense of smell, by which they find dead animals; Old World vultures rely mostly on their superlative sense of sight. Vultures, with long and broad wings, are perfectly adapted to soaring, using thermals and updrafts over hills and mountains to lift them high into the sky with almost no effort. From up there, they can keep an eye out for carcasses. Once one vulture spots potential food, other vultures watching it will see it going down and follow, and so no carcass gets left alone for too long.
At a carcass, different vulture species fulfill different roles. In Africa, the powerful Lappet-faced Vulture Torgos tracheliotos with its strong, hooked bill is able to tear through tough hides and open up intact carcasses so that it and other vultures can feed on the flesh and entrails inside. It also performs the final clean-up acts of eating the hides and sinews after the other vultures have consumed the softer bits. The Bearded Vulture specializes in eating bones, which it can swallow whole or, if too large, drop from a great height onto rocks to shatter. Most other vultures prefer to feed on softer tissues. They rapidly gorge themselves, extending their crops, sometimes eating so much that they have to wait around for some time before they are able to fly off. If they suddenly have to fly, if, for instance a hungry hyena turns up, they will quickly vomit up some of their meal. A few vulture species have somewhat wider feeding strategies, including catching live prey, as the Lappet-faced Vulture does, or feeding on ostrich eggs, which the Egyptian Vulture does using rocks as a tool to crack their shells. The Palm-nut Vulture, while eating carrion occasionally, actually specializes in eating the oily fruit of raffia and oil palm trees.
Vultures are among the largest and most spectacular birds. The Andean Vultur gryphus and Californian Gymnogyps californianus Condors, and several Old World vultures like the Lappet-faced Vulture, can reach body weights of more than 12 kg, and wingspans approaching or exceeding 3 m. The King Vulture Sarcoramphus papa of South America has one of the gaudiest faces in the bird kingdom, with colourful wattles and patches of bare skin. The Rüppell’s Vulture Gyps rueppelli has been recorded soaring at altitudes of 11,277 m, higher than any other bird. It would be interesting to know how they are able to tolerate both the extreme cold and lack of oxygen at that altitude.
In some parts of the world, vultures are seen in a very positive light. In the East, cultures such as the Parsi see vultures as performing a vital spiritual cleansing function; the dead are left on platforms called ‘towers of silence’ for the vultures to consume. In Ancient Egypt, the Egyptian Vulture was sometimes portrayed in hieroglyphics; the Mayans of Central America did the same with the King and Black Vulture.
VULTURES IN TROUBLE
Vultures, with the amazing ecosystem services they provide, are in deep trouble worldwide. The threats take different forms. The Californian Condor, almost went extinct because of eating the carcasses of animals that humans had shot; the lead bullets and shotgun pellets poisoned them. They were only saved by an intensive captive breeding effort. In India, the big threat is the drug diclofenac introduced to treat livestock. In Africa, vultures are hit particularly hard. They are poisoned, sometimes through poisoned carcasses left out by livestock farmers that want to kill jackals and other predators. Elephant and rhinos poachers worry that vultures circling and seeking out their kills, will draw anti-poaching units’ attention; so they poison the carcasses to intentionally kill vultures. In a recent incident, over 500 vultures comprising five different species died from scavenging poisoned elephant carcasses in Botswana.
In Africa, vultures are also considered to have medicinal value. Because of their keen eyesight, they are thought to be clairvoyant (able to predict the future), and vulture parts can sell for considerable prices at muti markets. Their carcasses also turn up at bush meat markets throughout Africa.
Many vultures suffer fatal accidents in collisions with human-made structures. They are prone to collisions with electricity pylons, and more recently, with the blades of wind turbines. The latter phenomenon is worrying. Wind farms kill not just vultures but also other species of birds, as well as bats. While wind power is often considered a ‘clean’ source of energy, it also has its own serious ecological repercussions. Furthermore, vultures face destruction of their habitats and food sources by humans. It is likely that several species of New World vultures went extinct when most of the megafauna (large mammals) such as mammoths, horses, camels and ground sloths were exterminated by humans entering these continents. In Africa and Asia, natural habitats are threatened by the ever increasing expansion of human settlements and agriculture, and the numbers of large, wild mammals continue to dwindle too.
What makes vultures especially vulnerable is that they are long-lived, slow-reproducing birds. Even under the best conditions, they take a long time to recover from population losses. At present, more than half of the Old World vulture species are considered endangered in some way! The New World vultures seem to be somewhat safer, but not entirely out of danger.
HOW WE CAN HELP
To protect vultures, they need protected habitat and large animals to feed on. It is important that we eliminate chemicals such as diclofenac that poison them. There are veterinary drugs that do the same job without harming vultures. In Africa, we need ongoing efforts to combat elephant and rhino poaching, as well as the poisoning of other predators that lead to unwanted vulture deaths. One solution is the provision of safe livestock carcasses at ‘vulture restaurants’, which can serve a double role, first of all feeding the vultures, but secondly also attracting bird watchers and tourists. Most vulture restaurants have bird hides where people can sit and watch the vultures as they feed. This also helps to spread vulture awareness. In South Africa and Asia, there are now many such vulture restaurants. We certainly need to continue with our efforts to conserve these precious, feathered eco-hygienists. Fore more information see: http://www.vulpro.com/ and https://www.ewt.org.za/what-we-do/what-we-do-species/vultures-for-africa/