Vultures are natures garbage disposers. Theyre perfectly adapted to keep the environment clean and healthy by efficiently situating and consuming carcass, recycling energy through the food web and preventing the spread of diseases. Its an unpaid role. However its about day we did start repaying vultures for their services, by giving them the protection they deserve.
A new survey published in the publication Genome Biology represents just how finely-tuned these birds are. The researchers perform a whole genome analysis of the Eurasian cinereous vulture ( Aegypius monachus ) and uncover a unique genetic make-up that explains vultures’ strongly acidic digestive system and their ability to defy infection from pathogens present in the rotting carcasses on which they feed.
Its even possible vultures are able to exploit the flesh-eating properties of some bacteria to aid with the digestion of soft tissues and bones, while the secretion of corrosive gastric acids and specialised immune responses allow them to resist infection from, and potentially even destroy, highly infective pathogens such as anthrax and brucellosis.
This unusual tolerance of natural toxins doesnt protect vultures from man-made contaminants however, which explains why 69% of vulture and condor species are listed as threatened or near-threatened, most of which are classed as imperiled or critically endangered. The California condor ( Gymnogyps californianus ), for example, was declared extinct in the wild in 1987 when the last remaining individuals were removed and placed in captivity to protect them from lead poisoning from ingesting shot and bullet fragments from hunted carcass. Although captive-breeding and release programs have allowed the wild population to increase to more than 200 someones, lead poisoning continues to cause fatalities.
Across Asia the great problem is accidental poisoning by diclofenac, an anti-inflammatory used to treat cattle. In vultures and some eagle species, tiny tracings of the drug can lead to fatal kidney failure within 48 hours. In simply 15 years, cow carcass polluted with diclofenac nearly wiped out three of Asias vulture species.
Indias vulture population collapsed faster than any bird in history including the dodo. Farooq Khan/ EPA
This had a big knock-on effect. With less competition at carcass disposal dumps, where people once let vultures pick dead animals clean, Indias feral puppy population exploded. This caused higher rates of rabies transmission at an estimated additional cost of US $34 billion to the countrys healthcare between 1993 and 2006.
Although some populations have started to recover following the ban of diclofenac in India in 2006, a logic-defying 2013 acceptance to licence the drug for use in Europe now threatens vultures there too, particularly in Spain and Italy. In Spain, replacing the natural carcass disposal service provided by vultures with vehicle transport to processing plants would result in the equivalent of an additional 77,344 metric tons of CO 2 being emitted to the ambiance and US $50 m of additional pays to insurance companies each year, according to a 2014 study in Nature.
The situation in Africa is just as grim another continental vulture crisis, as one group of researchers described it earlier this year. Populations of seven species have declined by more than 80% in three generations, giving rise to calls for six of those to be listed as critically endangered.
Once again man-made toxins and illegal activities are to blame. Poisoning accounts for 61% of vulture demises, 29% are attributed to the trade in vulture heads and brains for local cultural beliefs# and 9% of fatalities are caused by electrocution or crash with power lines.
Widespread poisoning is certainly the most immediate menace. Usually this happens after farmers target lions, leopards or hyenas that have been attacking their livestock. Vultures eat the poisoned predators or the baited carcass itself and subsequently become secondary, inadvertent victims.
One poisoned elephant carcass could infect many vultures .
However the booming illegal trade in tusk and rhino horn is also bad news for them, as poachers dont want hundreds of circling vultures pointing authorities towards recently-killed elephants or rhinos. Poachers are therefore purposely targeting the birds by lacing carcasses with poisons even after theyve left with the tusks or cornets. More than 500 vultures were poisoned at a single poached elephant carcass in Namibia in July 2013, and the recent discovery of at least 26 elephants poisoned at cyanide-laced water hole in Zimbabwe will also likely result in many vulture deaths.
Vultures Need Better
Why isnt this a bigger scandal? After all, as many, if not more vultures are being killed in southern Africa each year as rhinos or elephants. Perhaps these big, bald, flesh-eating birds are perceived as sinister and absence enough cute factor.
But while vultures dont share the good looks of penguins or puffins, the ecosystem services they provide are irreplaceable. They compete with and control populations of blowfly larvae, rats, feral dogs and other scavengers, many of which are illnes vectors. They ultimately make the world cleaner and healthier.
In fact, the ecological niche occupied by todays vulture species is so specialised that two unrelated groups evolved on opposite sides of the world to become the primary scavengers in their ecosystems. Old World vultures from Eurasia and Africa and New world vultures and condors from the Americas might seem and act the same but as the latest study highlights they dont share a recent common ancestor, having diverged in evolutionary words more than 60 m years ago.
This is a classic example of convergent evolution while Old world vultures share a common pedigree with eagles and New World species are more closely related to storks, they independently evolved similar specialisations to fulfil the important role of recycling carrion.
Its time for us to appreciate these unique and highly-specialised birds. We must restrict harmful veterinary narcotics, control illegal poisoning, provide uncontaminated sources of food and reduce the impact of power lines and wind farms. This must happen immediately to avoid a worldwide vulture crisis and all of the negative implications for our own health and well-being.
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