31 January 2014 Last updated at 01:58
Seven surprising facts about vultures
By Ella Davies Reporter, BBC Nature
Bald, ugly birds with a gruesome taste for gore or charismatic creatures that do an essential but thankless job in the ecosystem?
However we perceive them, one thing is clear about vultures – they are in trouble.
In India, Nepal and Pakistan populations have plummeted by 95% in the last decade and the pattern is being mirrored across Africa.
The birds are being poisoned through the carcasses they clear up. While some of this is the result of medication in livestock, other cases suggest intentional foul play by poachers that target the birds so they don’t alert wardens to dead rhinos and elephants.
Conservationists such as Simon Thomsett are working to raise awareness of the birds’ plight and change attitudes towards them by highlighting their unique adaptations.
1. Highest flyers
The highest bird flight ever recorded was by a Ruppell’s vulture which impacted an aircraft at 37,000ft over the Ivory Coast in 1973. This is well above the height of Everest (29,029 ft) and the lack of oxygen would kill most other birds.
“Since then studies on this vulture revealed a number of features in their haemoglobin and a number of cardio-vascular adaptations that allow breathing in rarefied atmosphere,” explains Mr Thomsett.
Vultures routinely soar high in the air, using thermals to get a wide view of the plains so they can find food.
2. Africa’s biggest appetites
A vulture’s life
See vultures finding their next meal from seven miles up
How do vultures spot carrion from so far away?
Watch vultures catch a lift using the hot air of thermals
“Every visitor to Africa assumes that the major consumers of wild animals are lions, hyenas, leopards, cheetahs, wild dogs and jackals. But they are not,” says Mr Thomsett.
He gives the Serengeti as an example where the total biomass of dead grazing animals is estimated to exceed 40 million tonnes per year.
“The [mammalian] carnivores can consume only some 36% and the rest is available to vultures. Bacteria and maggots compete with vultures for this resource, but vultures remain the largest consumers.”
Their role as the ultimate recyclers is said to help stop the spread of disease as well as limit populations of other scavengers such as wild dogs.
3. Borders are not boundaries
Vultures can fly considerable distances for a meal; one Ruppell’s vulture was recently recorded travelling north from its nest in Tanzania, across Kenya to a region in Sudan and Ethiopia.
The international team of researchers found that instead of closely following the mass migration of wildebeest through the Masai Mara, the birds sought out their prey in the dry season when they were most vulnerable due to drought.
This border-crossing behaviour has landed the birds in bother, notably when a griffon vulture discovered in Saudi Arabia was accused by local media of being an Israeli spy.
The bird had been tagged by a team at Tel Aviv University as part of a study into their movements and officials reportedly resolved the misunderstanding.
4. Powerful pee
Turkey vultures urinate on their legs and while this sounds unpleasant, scientists suspect the behaviour could be an essential part of their immunity arsenal.
Acid present in the urine could act as a way of sterilising the birds legs after standing in rotting flesh to feed.
5. Powerful expansion
Cape vultures in South Africa were tracked following power lines and pylons to cover a straight-line distance of 620 miles (1000 km).
The journey far outstripped the known range of the birds but using such manmade structures is also fraught with danger.
Whether perching or nesting on pylons, the vultures can become entangled in the lines and risk being electrocuted.
The power lines also run through private farmland and foraging near livestock leaves the birds more vulnerable to poisoning.
6. Varied diet
They might be famed for tucking in to the rotting sinews and viscera of dead animals but not all vultures have a carrion-only diet.
The palm nut vulture, as its name suggests, enjoys a varied menu of palm nuts, figs, fish and occasionally birds. At carcasses it prefers the insects and maggots living on the flesh.
The lappet-faced vulture meanwhile is a large African species with a wing span of up to 2.9m (9.5ft) and has been observed preying on live flamingo chicks.
7. Strong stomachs
Bearded vultures are the only animals known to have a diet of 70-90% bone and their stomach acid allows them to take nutrients from what other species discard.
Vultures are well known for their incredibly strong stomach acid which can destroy bacteria, including cholera and anthrax, that would prove deadly to many other species.
They also carry special antibodies to help them tackle botulism toxins so that even if the illness killed their prey, the vultures can eat it without negative effects.
Cameraman and naturalist Charlie Hamilton-James seeks to better understand the birds in Vultures: Beauty in the Beast on BBC Two at 2100 GMT, Friday 31 January.
More on This Story
The plight of India’s vulture populations, and their rapid decline due to the use of the drug diclofenac in cattle, is well documented. What’s less known is revealed in a new documentary (shown tonight, 31 January, in England and Wales and tomorrow, 1 February, in Scotland) in which renowned wildlife photojournalist and cameraman, Charlie Hamilton James, travels to East Africa to learn that vultures there are similarly declining at an alarming rate, but for a different reason: here.