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Inability of vultures to digest diclofenac

Inability of vultures to digest diclofenac



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The population of Indian vultures has been rapidly declining since 2003. This is attributed to the diclofenac present in the carcasses which the vultures eat. Vultures seem to digest all sorts of food items but why can't they digest diclofenac? What is the mechanism which causes this?


Via: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1618889/

Post-mortem examination revealed extensive visceral gout in all diclofenac-treated birds (see electronic supplementary material). Histological examination revealed significant lesions in the kidneys, liver and spleen with extensive uric acid crystal deposition.

Via: https://repository.up.ac.za/bitstream/handle/2263/26027/Complete.pdf?sequence=7

From the mechanistic studies both diclofenac and meloxicam were directly toxic to chicken and vulture renal tubular epithelial cells following 48h of incubation. It was later shown that this toxicity was associated with an increased production of reactive oxygen species (ROS), which could be temporarily ameliorated by pre-incubation with uric acid due to its anti-oxidant activity. When cultures were incubated with either drug for only two hours, meloxicam showed no toxicity in contrast to the cellular toxicity present for diclofenac. In both cases no increase in ROS production was evident. In addition, diclofenac influenced the excretion of uric acid by interfering with p-amino-hippuric acid channels. The effect on uric acid excretion persisted after the removal of the diclofenac. It was therefore concluded that vulture susceptibility to diclofenac results from a combination of an increase in cellular ROS, a depletion of intracellular uric acid concentration and most importantly the drug's long half-life in the vulture.

The second link posits three mechanisms for the cause of renal failure in vultures (ref., pg. 26):

  1. Ischaemic nephropathy with secondary visceral gout
  2. Organic Anion Transporter antagonism
  3. Secondary renal toxicity with or without toxic activation

Why vultures matter—and what we lose if they're gone

Hooded Vultures and Thick-billed Ravens searching for food in an urban setting, Addis Ababa, Ethiopia. Credit: Evan R. Buechley

Vultures. Cartoon characters in parched deserts often wish them to disappear, since circling vultures are a stereotypical harbinger of death. But, joking aside, vultures in some parts of the world are in danger of disappearing. And according to a new report from University of Utah biologists, such a loss would have serious consequences for ecosystems and human populations alike.

The primary threat to vultures, according to the report published today in Biological Conservation, is the presence of toxins in the carrion they consume. On many continents, vultures are the unfortunate victims of poisoned carcasses—especially impactful because dozens—or even hundreds—of vultures can feast on a single carcass. Populations of most vulture species around the world are now either declining or on the brink of extinction.

Losses of vultures can allow other scavengers to flourish, according to biologists Evan Buechley and Ça?an ?ekercio?lu. Proliferation of such scavengers could bring bacteria and viruses from carcasses into human cities.

Risk factors for decline

In 2004, ?ekercio?lu published a study examining the respective extinction risks of all bird species throughout the world. He noted then that vultures represented the single most threatened group of birds. Now, more than a decade later, Buechley and ?ekercio?lu have examined factors affecting the extinction risk of more than 100 bird species, including 22 species of vultures, which eat carrion exclusively, and other scavenging birds that have broader diets.

Their results suggest several inherent ecological traits that likely contribute to vultures' extinction risk, including their large body masses, slow reproductive rates and highly specialized diets. The greatest external threat to vultures, however, is poisoning.

Poisoning on three continents

Poisoning is the greatest extinction risk facing vultures, and impacts 88 percent of threatened vulture species. The poisons come in many forms.

In North America, the California condor, a vulture, experienced sharp declines until only 22 individuals remained by 1982. The leading cause of decline? Toxic lead bullet fragments in the gut piles left behind by hunters after animals had been field-dressed. Intensive conservation efforts helped the species to rebound. The condors now number well over 400, and range over large areas of California, Arizona, Utah and Baja California, Mexico.

In the mid-1990s India experienced a precipitous vulture decline, with more than 95 percent of vultures disappearing by the early 2000s. "That was a massive collapse that led a lot of people to really focus more attention on vultures," Buechley says. The cause was eventually traced to diclofenac, a veterinary anti-inflammatory drug that relieved pain in cattle, but proved highly toxic to vultures. Hundreds of vultures would flock to each cattle carcass. And if the cow had recently been treated with diclofenac, hundreds of vultures would die. Because of this highly gregarious feeding behavior, less than one percent of cattle carcasses contaminated with diclofenac could account for the steep vulture decline. Fortunately, international cooperation led to a total ban on veterinary diclofenac use. Buechley says the numbers of vultures have stabilized, and are now showing signs of slowly increasing.

An adult Hooded Vulture in Ethiopia is shown. The once common Hooded Vulture was uplisted to critically endangered in 2015 because of drastic declines in populations across Africa. Hooded vultures are dying primarily from poisons in the carrion they eat. Credit: Evan R. Buechley

Now, the center of the vulture crisis is in sub-Saharan Africa. "In Africa, it's a lot more challenging," Buechley says. "It's a darker story." Potent newly affordable poisons are used to control predatory pests, such as lions or jackals. The poisons are so toxic that they can cascade through ecosystems: birds, mammals and insects are often found littering the area around these poisoned carcasses. But, as the predominant scavenger, vultures take the brunt of the poisoning and face the largest number of casualties. For example, an elephant carcass poisoned in Namibia in 2007 killed as many as 600 vultures. In other cases, vultures are the victims of poachers who poison carcasses so that vultures do not give away the location of illegally taken animals. "Vultures are taking the hit, indirectly, for a lot of this human-wildlife conflict, as well as the illegal trade in animal parts," Buechley says. This crisis, unfortunately, is ongoing.

Rise of the facultative scavengers

In vultures' absence, other scavenger populations increase to take advantage of all of the uneaten carrion. By some estimates, in Central America, South America and Africa, vultures eat more meat than all predators combined. Without vultures, animals that eat carrion as a part of their diet (called facultative scavengers, as opposed to vultures, which eat only carrion) proliferate to take advantage of the available nutrients in a dead carcass. "There are a ton of nutrients in carrion that are going to be taken advantage of by something," Buechley says.

Crows, rats, dogs—any of these species can suddenly become abundant and dominant, to the point of crowding out the remaining vultures. Hundreds of vultures on a carcass can easily frighten away packs of dogs, ?ekercio?lu says. But when only a few vultures are left, the dogs can rule.

Such changes in populations of certain animal groups can upset the balance of food webs. "All these facultative scavengers are also predators, and so they also go out and eat other organisms too," Buechley says. "You have this cascading effect."

The impact of vultures' declines are not limited to the realm of ecology, however. Vultures are highly efficient consumers of carrion, sometimes locating and consuming carcasses within an hour, before other forms of decay can set in. And vultures' stomachs are highly acidic, killing nearly all bacteria or viruses that may be present in carrion. Combined with the fact that vultures rarely come in contact with humans, vultures serve as a barrier to prevent diseases from proliferating in dead animals and spreading to humans. Other facultative scavengers are not so adapted, and could pass along those diseases into human populations, as many are already fixtures in cities.For example, following the decline of vultures, India experienced a strong uptick in feral dogs —by an estimated seven million. The increase in dogs, potentially feeding on disease-ridden carcasses, is thought to have at least partially caused the rabies outbreak that was estimated to have killed 48,000 people from 1992-2006 in India—deaths that may have been avoided if not for the disappearance of vultures.

Members of the Parsi sect of Zoroastrianism experienced a different impact. For thousands of years, the Parsi people have placed their dead on exposed mountaintops or tall towers for vultures to consume. The practice is called "sky burial."

But with few vultures and unable to properly handle their dead, the Parsis experienced a crisis within the faith. Some constructed captive vulture aviaries. Others talked about desiccating bodies using focused solar mirrors. The Parsis' plight exemplifies the vultures' role in south Asian society—and the various impacts if the vultures aren't there.

Learning from the past

Although the vulture crisis in Africa is ongoing, Buechley and ?ekercio?lu can predict what the outcome will be, based on previous experiences in India. Crows, gulls, rats and dogs will boom. And the rabies outbreak in India may just be a prologue, because several sub-Saharan Africa countries already have the highest per-capita rabies infection rates in the world. Rabies is only one of the many potential diseases that vultures had helped regulate.

Buechley notes that the poisoning that is killing vultures is also affecting many other organisms throughout ecosystems. But vultures are the most sensitive canaries in ecological coal mines. The story of the California condor shows that recovery is possible, but at a high cost that countries in the developing world may not be able to pay.

"It's good news and bad news," ?ekercio?lu says. "It shows that we can bring back these scavengers. But the bad news is that once we get to these numbers, it costs tens of millions of dollars and decades to bring them back. You don't want to go there. And once you go there, we can afford to save only a few species."

So, Buechley argues, "the better solution is to invest in vulture conservation here and now, in order to stem incalculable damage from trophic cascades and increased human disease burden in the developing world."


Majority of them die due to poisoning and their decline may push up numbers of feral dogs and other scavengers in human habitats.

Decline in vulture populations in some parts of the world, including India, may have serious consequences for ecosystems and humans alike, according to a new study that suggests poisoning is the greatest extinction risk facing the scavengers.

Poisoning is the greatest extinction risk facing vultures, and impacts 88 per cent of threatened vulture species, researchers from University of Utah in the U.S. have said.

They are unfortunate victims

In many continents, vultures are the unfortunate victims of poisoned carcasses — especially impactful because dozens, or even hundreds — of vultures can feast on a single carcass, they said.

Populations of most vulture species around the world are now either declining or on the brink of extinction.

Other scavengers will enter human habitat

Losses of vultures can allow other scavengers to flourish. Proliferation of such scavengers could bring bacteria and viruses from carcasses into human cities, researchers said.

They examined factors affecting the extinction risk of more than 100 bird species, including 22 species of vultures, which eat carrion exclusively, and other scavenging birds that have broader diets.

Their make could be their unmaking

The results suggest several inherent ecological traits that likely contribute to vultures’ extinction risk, including their large body masses, slow reproductive rates and highly specialised diets, researchers said.

In the mid-1990s India experienced a precipitous vulture decline, with more than 95 per cent of vultures disappearing by the early 2000s, they said.

“That was a massive collapse that led a lot of people to really focus more attention on vultures,” said Evan Buechley from the University of Utah.

This drug called diclofenac

The cause was eventually traced to diclofenac, a veterinary anti-inflammatory drug that relieved pain in cattle, but proved highly toxic to vultures, researchers said.

Hundreds of vultures would flock to each cattle carcass.

And if the cattle had recently been treated with diclofenac, hundreds of vultures would die, they said.

Because of this highly gregarious feeding behaviour, less than one per cent of cattle carcasses contaminated with diclofenac could account for the steep vulture decline.

Spurt in feral dogs and the rabies link

Following the decline of vultures, India experienced a strong uptick in feral dogs — by an estimated seven million, researchers said.

The increase in dogs, potentially feeding on disease-ridden carcasses, is thought to have at least partially caused the rabies outbreak that was estimated to have killed 48,000 people from 1992-2006 in India — deaths that may have been avoided if not for the disappearance of vultures, researchers said.

It is happening in sub-Saharan Africa

Now, the centre of the vulture crisis is in sub-Saharan Africa, they said.

“In Africa, it is a lot more challenging. It is a darker story,” said Buechley.

The findings were published in the journal Biological Conservation.


Drugs, Fast Trains Killing Vultures, the ‘Sanitary Workers’ of the Animal Kingdom

On March 17, 36 vultures died in Sivasagar, Assam after feeding on a poisoned goat carcass intended as bait for feral dogs. The 36 vultures belonged to three different species, namely, the Himalayan griffon (Gyps himalayensis), Oriental white-backed (Gyps bengalensis) and slender-billed (Gyps tenuirostris) vulture, of which the last two are critically endangered. The birds died within half an hour of feeding on the carcass. Seven others were rescued, rehabilitated and released.

This is not a lone incident of vultures dying en masse in India, and poisons are not the only killers of these scavenging raptors. Since December last year, more than 60 vultures have been found dead along the Jaisalmer-Ramdevra railway track in Rajasthan.

Sumit Dookia, a conservationist and ecologist who worked on the Rajasthan case, told The Wire that about 15% of the vultures in Jaisalmer could have died after being hit by trains in the last 6 months. The vulture deaths are linked to the death of other animals near the track, particularly that of cows. Villagers from Dholia and Khetolai in Jaisalmer have tried to remove animal carcasses from near the railway tracks to prevent vultures from getting mowed down by trains, but that has not completely solved the problem, according to Dookia.

This is also not a lone incident of vultures getting mowed down by trains. In another episode that occurred near Jorbeer Vulture Sanctuary in Rajasthan in April 2017, 31 vultures were killed by a train.

Speaking to The Wire, Chris Bowden, the co-chair of the vulture specialist group at the International Union of Conservation of Nature (IUCN), said, “When vultures feed on carcasses in large numbers, many have their heads buried deep in the animal’s flesh, and are unfortunately not well adapted to fast moving trains appearing suddenly”. He added that the trains catch the vultures in a particularly vulnerable moment when they are weighed down with full crop, unable to quickly fly high or away from oncoming trains.

Three decade-long vulture deaths

Environmentalists are fighting tooth and nail to record and formulate plans to prevent vulture deaths, as India has been facing mass mortality of vultures. Three of India’s vulture species have been on the list of critically endangered animals since 2000. Almost 95% of the raptors in India were dead by 2003, and more than 99% were wiped out by 2008. A paper published in Bird Conservation International in December 2017, noted that the population of the three Gyps species of vultures inhabiting India reduced from millions in the 1970s, to a few thousands.

Vibhu Prakash, principal scientist at the Bombay Natural History Society (BNHS), was one of the first to note the decline. Between 1987-1988, he counted 353 nesting pairs of vultures in 29 square-km area of Keoladeo National Park in Bharatpur, Rajasthan, which, by 1998-1999, came down to 20, with no breeding pairs observed in the subsequent years. The decline continued, till vultures were completely wiped out in Bharatpur. Soon, similar reports poured in from across the country of the mass mortality of vultures. Since vultures play critical roles in the ecosystem, their mass mortality has had cascading effects, even on the economy.

Consequences of a vulture population decline

Vultures are extremely efficient scavengers. They can dig deep into dead animals, and 15-20 vultures working together can bring a cattle carcass down to its bone within 20 minutes. With their powerfully corrosive stomach acids, they can safely digest rotting carcass, even those teeming with bacteria that cause deadly diseases like botulism and anthrax. The Madras high court even addressed vultures as ‘sanitary workers’ for their valuable services in disposing off cattle carcasses.

In India, a decline in vulture population by about 10 million between 1992 and 2003, coincided with an increase in dog population from 3.7 million to 7.3 million. Though it is very difficult to find the direct contribution of vulture deaths to the dog population explosion, a large portion of carrion consumed by vultures was made available for dogs during that period.

A study published in 2008 by Anil Markandya, a resource economist at University of Bath, estimated the total cost to the Indian government due to the vulture population decline. He calculated that the population expansion of dogs due to vulture deaths, between 1992 and 2006, resulted in over 38.5 million additional dog bites. From this, Markandya estimated that 47,300 people would have died from rabies, many succumbing to it despite treatment.

The paper further estimated that the mass mortality of vultures during the period may have indirectly cost the Indian government over USD 34 million in treatment costs. It also stated that elimination of vultures could lead to an outburst of rat populations, causing an increased risk of rat-borne epidemic outbreaks like leptospirosis and noted that the neglected carcasses could also act as incubators for microorganisms causing diseases like tuberculosis, anthrax, and foot-and-mouth disease.

There are cultural costs of vulture deaths as well. The Parsi community has a unique funeral ritual where they lay their dead in tall structures called “Towers of Silence” to be consumed by scavenger birds. With the sharp decline in vulture population, this practice could not be sustained.

A decade-long probe into the causes

Worried, environmentalists sought to find the main reason for the vulture deaths. While there were numerous factors that could have been responsible, they narrowed down the list to a few major suspects. The initial suspicion was on poisoned carcass, as reported by Down To Earth in 1999.

Rodenticide was also suspected, as it is commonly used by cattle-lifters to kill cows for their bones and skin. There were also doubt of pesticides indirectly causing the death of vultures, similar to the case of DDT killing off bald eagles in USA in the 1960s. Factors like habitat destruction, poaching or epidemics could also not be ruled out easily.

Then, the collective efforts of the Peregrine Fund and a team of more than a dozen scientists found that the deaths were caused when vultures consumed dead cows treated with the drug Diclofenac – an anti-inflammatory drug intended for humans and used to treat sick cattle. The team found that the cheap and fast-acting pain killer, belonging to the class of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), had disastrous effects on a vulture’s kidneys, causing severe gout and death within 72 hours. Soon, four other NSAIDs were also found to be poisonous to vultures.

“Non-steroidal anti-inflammatory drugs, most notably diclofenac, but now joined by ketoprofen, aceclofenac and nimesulide, used by vets to treat cattle, were [the] hidden and widespread killers of 40 million vultures over the past 20 years in India. They kill slowly, over several days, so the dead vultures are highly dispersed and go unseen.” Bowden told The Wire.

Even after the major cause of death was found, environmentalists had to move a mountain to bring regulations on the use of the drug. After constant battle since the 90s, veterinary use of diclofenac was banned by the Indian government only in 2006. And later in November 2017, the Union Ministry of Health and Family Welfare banned multi-dose vials of the drug. After several NSAIDs were found to kill vultures, Meloxicam, which was proven to be safe for the raptors, has been promoted as an alternative.

Conservation efforts and aftermath of diclofenac ban

Vulture numbers began stabilising slowly after the diclofenac ban, and between 2011 and 2012, there was a slight increase in the population. However, for a successful recovery, environmentalists like Dookia believe that the threat posed by transmission lines, train routes and wind turbines must also be looked into. Bowden believes that any covert use of NSAIDs to treat cattle would prevent the recovery of the raptor’s population.

The main challenge facing vulture conservation is that even today carrion continues to show the presence of diclofenac. BNHS tested the carcasses of lifestocks across the country and found that 6% of the dead animals still showed traces of diclofenac – a number that is still too high for vultures to recover, according to Vibhu Prakash.

Satish Pande, ornithologist and part of the ELA Foundation, noted that farmers spray pesticides on dead animals or bury them to prevent the smell of putrefaction, taking more food off the vultures’ tables. Hence, experts like Prakash believe that safe food should be provided at breeding centres till the vultures are reared to adulthood. The Phansad Wildlife Sanctuary in Maharashtra is one such centre where vultures are fed cattle, sheep or goat carcass, free from any drug contamination, every three to four days.

Since 2004, the Ministry of Environment and Forests has undertaken eight captive breeding programmes. Jatayu Conservation Breeding Centre in Pinjore, Haryana, is one such place housing more than 250 vultures belonging to the three majorly affected species. Likewise, there are breeding centres in Assam, Madhya Pradesh and West Bengal. But even with these centres, very few vultures have been released into the wild since the threat from diclofenac still lurks.

Thus, there is a need to establish certified safe zones to act as release sites for the birds reared in captivity. “Conservation breeding and release programmes have an important role to play in getting birds back into the wild.” said Bowden. He added that it was also important to test the safety levels of the release-areas using monitoring tools, and by planting tracking devices on released vultures.


Author information

Affiliations

Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, 99164-7040, USA

The Peregrine Fund, 5668 West Flying Hawk Lane, Boise, Idaho, 83709, USA

Martin Gilbert, Munir Z. Virani & Richard T. Watson

USGS–National Wildlife Health Center, 6006 Schroeder Road, Madison, Wisconsin, 53711-6223, USA

Center for Reproduction of Endangered Species, Zoological Society of San Diego, PO Box 120551, San Diego, California, 92112, USA

California Animal Health and Food Safety Laboratory System–Fresno Branch, University of California at Davis, 2789 S. Orange Avenue, Fresno, California, 93725, USA

Zoology Division, Institute of Pure and Applied Biology, Bahauddin Zakariya University, Multan, Pakistan

Shakeel Ahmed, Muhammad Jamshed Iqbal Chaudhry, Muhammad Arshad, Shahid Mahmood, Ahmad Ali & Aleem Ahmed Khan


Genetics explain why vultures are such good scavengers: new paper

Everybody knows that vultures are nature’s garbage cleaners. They perform an essential function by efficiently locating and consuming carcasses and preventing the spread of diseases, without getting ill – vultures resist infection from such highly infective pathogens as anthrax and brucellosis.

Now a new study published recently in the journal Genome Biology (you can download it below) explains how they do it: they have a unique genetic make-up that allows them to digest carcasses and guard themselves against constant exposure to pathogens . A team from the Ulsan National Institute of Science and Technology (South Korea) sequenced the genome of a cinereous vulture and compared it to that of the North American bald eagle.

These researchers found that vultures have variations in the genes relating to the regulation of gastric acid secretion. This is consistent with the ability to eat rotting meat. They also have variations relating to immunity and defence against viral and microbial infections – including genes that allow cells to target pathogens of ingestion and elimination.

It was well known that vultures had strong immune systems and mechanisms to stop infection – what this paper shows are that these are underlined by genetic variations .

The researchers were also able to determine that the species is far more closely related to the North American bald eagle than had previously been thought, perhaps more closely related than to new world vultures. According to the study, Old World vulture species split from the New World 60 million years ago, but the cinereous vulture only diverged from the North American bald eagle around 18 million years ago.

“Old World” vultures from Eurasia and Africa and “New World” vultures and condors from the Americas might look the same and fill in the same ecological role, due to “convergent evolution”, but in fact they are evolutionary very separate - Old World vultures share a common ancestry with eagles while New World species are more closely related to storks.

They resist natural toxins – but not man-made ones

This unusual tolerance of natural toxins doesn’t protect vultures from man-made contaminants however – man-made toxins, poisons and veterinary drugs like diclofenac. As a result two thirds of the 23 vulture species in the world are listed as threatened or near-threatened.

In spite of their bad press, it’s time for us to appreciate and value what these unique and highly-specialised birds do for us – clean our environment in the most effective way. Help us save vultures!


Photo - a cinereous vulture scavenging in the middle of griffon vultures. Bruno Berthemy/VCF


Contents

Zoroastrian tradition considers human cadavers and animal corpses (in addition to cut hair and nail parings) to be nasu, unclean, i.e. potential pollutants. [1] [2] [3] Specifically, the corpse demon (Avestan: nasu.daeva) was believed to rush into the body and contaminate everything it came into contact with, [3] [4] hence the Vīdēvdād (an ecclesiastical code "given against the demons") has rules for disposing of the dead as safely as possible. [1] Moreover, the Vīdēvdād requires that graves, and raised tombs as well, must be destroyed. [1]

To preclude the pollution of the sacred elements: Earth, Water, and Fire (see Zam and Atar respectively), the bodies of the dead are placed at the top of towers and so exposed to the sun and to scavenging birds and wild dogs. [1] [2] [3] Thus, "putrefaction with all its concomitant evils. is most effectually prevented." [5]

Zoroastrian ritual exposure of the dead is first known of from the writings of the Ancient Greek historian Herodotus (mid-5th century BCE), who observed the custom amongst Iranian expatriates in Asia Minor. [2] In Herodotus' account (Histories i.140), the Zoroastrian funerary rites are said to have been "secret", but were first performed after the body had been dragged around by a bird or dog. The corpse was then embalmed with wax and laid in a trench. [6] : 204

While the discovery of ossuaries in both Eastern and Western Iran dating to the 5th and 4th centuries BCE indicates that bones were isolated, that this separation occurred through ritual exposure cannot be assumed: burial mounds, [7] where the bodies were wrapped in wax, have also been discovered. The tombs of the Achaemenid Emperors at Naqsh-e Rustam and Pasargadae likewise suggest non-exposure, at least until the bones could be collected. According to legend (incorporated by Ferdowsi into his Shahnameh), Zoroaster himself is interred in a tomb at Balkh (present-day Afghanistan).

Writing on the culture of the Persians, Herodotus reports on the Persian burial customs performed by the Magi, which are kept secret. However, he writes that he knows they expose the body of male dead to dogs and birds of prey, then they cover the corpse in wax, and then it is buried. [8] The Achaemenid custom is recorded for the dead in the regions of Bactria, Sogdia, and Hyrcania, but not in Western Iran. [9]

The Byzantine historian Agathias has described the Zoroastrian burial of the Sasanian general Mihr-Mihroe: "the attendants of Mermeroes took up his body and removed it to a place outside the city and laid it there as it was, alone and uncovered according to their traditional custom, as refuse for dogs and horrible carrion". [9]

Towers are a much later invention and are first documented in the early 9th century CE. [10] : 156–162 The funerary ritual customs surrounding that practice appear to date to the Sassanid Era (3rd–7th CE). They are known in detail from the supplement to the Shayest ne Shayest, the two Rivayat collections, and the two Saddars.

The modern-day towers, which are fairly uniform in their construction, have an almost flat roof, with the perimeter being slightly higher than the centre. The roof is divided into three concentric rings: the bodies of men are arranged around the outer ring, women in the second ring, and children in the innermost ring. Once the bones have been bleached by the sun and wind, which can take as long as a year, they are collected in an ossuary pit at the centre of the tower, where–assisted by lime–they gradually disintegrate, and the remaining material–along with run-off rainwater–runs through multiple coal and sand filters before being eventually washed out to sea. The ritual precinct may be entered only by a special class of pallbearers, called nusessalars, a contraction of nasa.salar, caretaker (-salar) of potintial pollutants (nasa-).

In Iran Edit

In the Iranian Zoroastrian tradition, the towers were built atop hills or low mountains in desert locations distant from population centers. In the early twentieth century, the Iranian Zoroastrians gradually discontinued their use and began to favour burial or cremation.

The decision to change the system was accelerated by three considerations: the first problem arose with the establishment of the Dar ul-Funun medical school. Since Islam considers unnecessary dissection of corpses as a form of mutilation, thus forbidding it, there were no corpses for study available through official channels. The towers were repeatedly broken into, much to the dismay of the Zoroastrian community. Secondly, while the towers had been built away from population centers, the growth of the towns led to the towers now being within city limits. Finally, many of the Zoroastrians found the system outdated. Following long negotiations between the anjuman societies of Yazd, Kerman, and Tehran, the latter gained a majority and established a cemetery some 10 km from Tehran at Ghassr-e Firouzeh (Firouzeh's Palace). The graves were lined with rocks and plastered with cement to prevent direct contact with the earth. In Yazd and Kerman, in addition to cemeteries, orthodox Zoroastrians continued to maintain a tower until the 1970s when ritual exposure was prohibited by law.

In India Edit

Following the rapid expansion of the Indian cities, the squat buildings are today in or near population centers, but separated from the metropolitan bustle by gardens or forests. In Parsi Zoroastrian tradition, exposure of the dead is also considered to be an individual's final act of charity, providing the birds with what would otherwise be destroyed.

In the late 20th century and early 21st century the vulture population on the Indian subcontinent declined (see Indian vulture crisis) by over 97% as of 2008, primarily due to diclofenac poisoning of the birds following the introduction of that drug for livestock in the 1990s, [11] until banned for cattle by the Indian government in 2006. The few surviving birds are often unable to fully consume the bodies. [12] In 2001, Parsi communities in India were evaluating captive breeding of vultures and the use of "solar concentrators" (which are essentially large mirrors) to accelerate decomposition. [13] Some have been forced to resort to burial, as the solar collectors work only in clear weather. Vultures used to dispose of a body in minutes, and no other method has proved fully effective.

The right to use the Towers of Silence is a much-debated issue among the Parsi community (see Parsi for details). The facilities are usually managed by the anjumans, the predominantly conservative local Zoroastrian associations (usually having five priests on a nine-member board). In accordance with Indian statutes, these associations have domestic authority over trust properties and have the right to grant or restrict entry and use, with the result that the associations frequently prohibit the use by the offspring of a "mixed marriage", that is, where one parent is a Parsi and the other is not.

The towers remain in use as sacred locations for the Parsi community, [14] though non-members may not enter them. [15] In Mumbai visitors are shown a model of a tower. Organized tours can be taken to the site.

Art and architectural features of the tower

- The towers are uniform in their construction.

- The roof of the tower is lower in the middle than the outer and is divided into three concentric circles.

- The dead bodies are placed on stone beds on the roof of the tower and there is a central ossuary pit, into which the bodies fall after eaten by vultures.

- The bodies disintegrate naturally assisted with lime and the remaining is washed off by rainwater into multiple filters of coal and sand, finally reaching the sea.


Why vultures matter -- and what we lose if they're gone

Vultures. Cartoon characters in parched deserts often wish them to disappear, since circling vultures are a stereotypical harbinger of death. But, joking aside, vultures in some parts of the world are in danger of disappearing. And according to a new report from University of Utah biologists, such a loss would have serious consequences for ecosystems and human populations alike.

The primary threat to vultures, according to the report published today in Biological Conservation, is the presence of toxins in the carrion they consume. On many continents, vultures are the unfortunate victims of poisoned carcasses -- especially impactful because dozens -- or even hundreds -- of vultures can feast on a single carcass. Populations of most vulture species around the world are now either declining or on the brink of extinction.

Losses of vultures can allow other scavengers to flourish, according to biologists Evan Buechley and Ça?an ?ekercio?lu. Proliferation of such scavengers could bring bacteria and viruses from carcasses into human cities.

Risk factors for decline

In 2004, ?ekercio?lu published a study examining the respective extinction risks of all bird species throughout the world. He noted then that vultures represented the single most threatened group of birds. Now, more than a decade later, Buechley and ?ekercio?lu have examined factors affecting the extinction risk of more than 100 bird species, including 22 species of vultures, which eat carrion exclusively, and other scavenging birds that have broader diets.

Their results suggest several inherent ecological traits that likely contribute to vultures' extinction risk, including their large body masses, slow reproductive rates and highly specialized diets. The greatest external threat to vultures, however, is poisoning.

Poisoning on three continents

Poisoning is the greatest extinction risk facing vultures, and impacts 88 percent of threatened vulture species. The poisons come in many forms.

In North America, the California condor, a vulture, experienced sharp declines until only 22 individuals remained by 1982. The leading cause of decline? Toxic lead bullet fragments in the gut piles left behind by hunters after animals had been field-dressed. Intensive conservation efforts helped the species to rebound. The condors now number well over 400, and range over large areas of California, Arizona, Utah and Baja California, Mexico.

In the mid-1990s India experienced a precipitous vulture decline, with more than 95 percent of vultures disappearing by the early 2000s. "That was a massive collapse that led a lot of people to really focus more attention on vultures," Buechley says. The cause was eventually traced to diclofenac, a veterinary anti-inflammatory drug that relieved pain in cattle, but proved highly toxic to vultures. Hundreds of vultures would flock to each cattle carcass. And if the cow had recently been treated with diclofenac, hundreds of vultures would die. Because of this highly gregarious feeding behavior, less than one percent of cattle carcasses contaminated with diclofenac could account for the steep vulture decline. Fortunately, international cooperation led to a total ban on veterinary diclofenac use. Buechley says the numbers of vultures have stabilized, and are now showing signs of slowly increasing.

Now, the center of the vulture crisis is in sub-Saharan Africa. "In Africa, it's a lot more challenging," Buechley says. "It's a darker story." Potent newly affordable poisons are used to control predatory pests, such as lions or jackals. The poisons are so toxic that they can cascade through ecosystems: birds, mammals and insects are often found littering the area around these poisoned carcasses. But, as the predominant scavenger, vultures take the brunt of the poisoning and face the largest number of casualties. For example, an elephant carcass poisoned in Namibia in 2007 killed as many as 600 vultures. In other cases, vultures are the victims of poachers who poison carcasses so that vultures do not give away the location of illegally taken animals. "Vultures are taking the hit, indirectly, for a lot of this human-wildlife conflict, as well as the illegal trade in animal parts," Buechley says. This crisis, unfortunately, is ongoing.

Rise of the facultative scavengers

In vultures' absence, other scavenger populations increase to take advantage of all of the uneaten carrion. By some estimates, in Central America, South America and Africa, vultures eat more meat than all predators combined. Without vultures, animals that eat carrion as a part of their diet (called facultative scavengers, as opposed to vultures, which eat only carrion) proliferate to take advantage of the available nutrients in a dead carcass. "There are a ton of nutrients in carrion that are going to be taken advantage of by something," Buechley says.

Crows, rats, dogs -- any of these species can suddenly become abundant and dominant, to the point of crowding out the remaining vultures. Hundreds of vultures on a carcass can easily frighten away packs of dogs, ?ekercio?lu says. But when only a few vultures are left, the dogs can rule.

Such changes in populations of certain animal groups can upset the balance of food webs. "All these facultative scavengers are also predators, and so they also go out and eat other organisms too," Buechley says. "You have this cascading effect."

The impact of vultures' declines are not limited to the realm of ecology, however. Vultures are highly efficient consumers of carrion, sometimes locating and consuming carcasses within an hour, before other forms of decay can set in. And vultures' stomachs are highly acidic, killing nearly all bacteria or viruses that may be present in carrion. Combined with the fact that vultures rarely come in contact with humans, vultures serve as a barrier to prevent diseases from proliferating in dead animals and spreading to humans. Other facultative scavengers are not so adapted, and could pass along those diseases into human populations, as many are already fixtures in cities. For example, following the decline of vultures, India experienced a strong uptick in feral dogs --by an estimated seven million. The increase in dogs, potentially feeding on disease-ridden carcasses, is thought to have at least partially caused the rabies outbreak that was estimated to have killed 48,000 people from 1992-2006 in India -- deaths that may have been avoided if not for the disappearance of vultures.

Members of the Parsi sect of Zoroastrianism experienced a different impact. For thousands of years, the Parsi people have placed their dead on exposed mountaintops or tall towers for vultures to consume. The practice is called "sky burial."

But with few vultures and unable to properly handle their dead, the Parsis experienced a crisis within the faith. Some constructed captive vulture aviaries. Others talked about desiccating bodies using focused solar mirrors. The Parsis' plight exemplifies the vultures' role in south Asian society -- and the various impacts if the vultures aren't there.

Learning from the past

Although the vulture crisis in Africa is ongoing, Buechley and ?ekercio?lu can predict what the outcome will be, based on previous experiences in India. Crows, gulls, rats and dogs will boom. And the rabies outbreak in India may just be a prologue, because several sub-Saharan Africa countries already have the highest per-capita rabies infection rates in the world. Rabies is only one of the many potential diseases that vultures had helped regulate.

Buechley notes that the poisoning that is killing vultures is also affecting many other organisms throughout ecosystems. But vultures are the most sensitive canaries in ecological coal mines. The story of the California condor shows that recovery is possible, but at a high cost that countries in the developing world may not be able to pay.

"It's good news and bad news," ?ekercio?lu says. "It shows that we can bring back these scavengers. But the bad news is that once we get to these numbers, it costs tens of millions of dollars and decades to bring them back. You don't want to go there. And once you go there, we can afford to save only a few species."

So, Buechley argues, "the better solution is to invest in vulture conservation here and now, in order to stem incalculable damage from trophic cascades and increased human disease burden in the developing world."

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.


One-Ninety Birds


As a volunteer at a local falconry centre (Pacific Northwest Raptors) and bona fide bird brain I feel slightly embarrassed for not fully informing myself of the vulture crisis in the past. I did not digest the grandeur of the crisis until a recent bicycle accident. This accident resulted in surgery, a cast for nine weeks and a screw in my wrist for life.

With great sorrow I learned that these vultures were only three of one-hundred and ninety critically endangered birds and three of 1859 species , subspecies and varieties of animalia on the verge of non-existence. I found myself in a rut unable to do many of the things that defined me as a person such as guitar, bicycling and falconry. But one of my favorite Latin quotes “post tenebras lux” translating to “after darkness light” comes to mind. Out of this accident I have decided to become an advocate for the vulture crisis.

Vultures play an important ecological role and with the sharpest decline experienced by any bird species the vulture situation in Asia is very much a crisis. The vulture population has dropped from ten’s of millions to mere thousands. Luckily for vultures in my opinion this decline is easily reversible by educating farmers and growing conservation efforts. I find it hard to avoid that our world is in crisis and at a crucial stage and turning point and needs our attention. My hopes are to bring light to he vulture crisis and to educate the ecological and cultural importance of vultures. I plan to use this web page as a resource for the vulture crisis and a blog for updates involving the crisis and my own experiences involved with raising awareness. If you have read this far I thank and revere you and hope you return. With that said I leave you with gratitude and some grim Jungle Book humour.


Why Vultures Matter – and What We Lose if They’re Gone

A Lappet-faced Vulture displaces a Ruppell’s Vulture from a road-kill dog carcass in Ethiopia. Two Lappet-faced Vultures subsequently feed on and drag the carcass away.

Hooded Vultures and Thick-billed Ravens searching for food in an urban setting, Addis Ababa, Ethiopia.

At a road-kill dog carcass in Ethiopia, a Bearded Vulture, the only vertebrate osteophage (bone-eating specialist), swallows a large section of dog vertebrae whole.

An adult Hooded Vulture in Ethiopia. The once common Hooded Vulture was uplisted to critically endangered in 2015 because of drastic declines in populations across Africa. Hooded vultures are dying primarily from poisons in the carrion they eat.

Evan R. Buechley releasing an adult Egyptian Vulture in Armenia after tagging it with a satellite tracking device (visible on the back of the bird). This device will allow detailed tracking of the movements in order to investigate where this endangered species is breeding, feeding, and migrating. Such technology is important for identifying critical habitat for the conservation of endangered vultures.

An adult critically endangered California Condor that was released into the wild in the Grand Canyon region of Arizona. California Condor populations are recovering across North America with extensive conservation efforts after reaching a population low of only 22 individuals in the 1980’s.

Newswise — Vultures. Cartoon characters in parched deserts often wish them to disappear, since circling vultures are a stereotypical harbinger of death. But, joking aside, vultures in some parts of the world are in danger of disappearing. And according to a new report from University of Utah biologists, such a loss would have serious consequences for ecosystems and human populations alike.

The primary threat to vultures, according to the report published today in Biological Conservation, is the presence of toxins in the carrion they consume. On many continents, vultures are the unfortunate victims of poisoned carcasses — especially impactful because dozens — or even hundreds — of vultures can feast on a single carcass. Populations of most vulture species around the world are now either declining or on the brink of extinction.

Losses of vultures can allow other scavengers to flourish, according to biologists Evan Buechley and Çağan Şekercioğlu. Proliferation of such scavengers could bring bacteria and viruses from carcasses into human cities.

Risk factors for declineIn 2004, Şekercioğlu published a study examining the respective extinction risks of all bird species throughout the world. He noted then that vultures represented the single most threatened group of birds. Now, more than a decade later, Buechley and Şekercioğlu have examined factors affecting the extinction risk of more than 100 bird species, including 22 species of vultures, which eat carrion exclusively, and other scavenging birds that have broader diets.

Their results suggest several inherent ecological traits that likely contribute to vultures’ extinction risk, including their large body masses, slow reproductive rates and highly specialized diets. The greatest external threat to vultures, however, is poisoning.

Poisoning on three continentsPoisoning is the greatest extinction risk facing vultures, and impacts 88 percent of threatened vulture species. The poisons come in many forms.

In North America, the California condor, a vulture, experienced sharp declines until only 22 individuals remained by 1982. The leading cause of decline? Toxic lead bullet fragments in the gut piles left behind by hunters after animals had been field-dressed. Intensive conservation efforts helped the species to rebound. The condors now number well over 400, and range over large areas of California, Arizona, Utah and Baja California, Mexico.

In the mid-1990s India experienced a precipitous vulture decline, with more than 95 percent of vultures disappearing by the early 2000s. “That was a massive collapse that led a lot of people to really focus more attention on vultures,” Buechley says. The cause was eventually traced to diclofenac, a veterinary anti-inflammatory drug that relieved pain in cattle, but proved highly toxic to vultures. Hundreds of vultures would flock to each cattle carcass. And if the cow had recently been treated with diclofenac, hundreds of vultures would die. Because of this highly gregarious feeding behavior, less than one percent of cattle carcasses contaminated with diclofenac could account for the steep vulture decline. Fortunately, international cooperation led to a total ban on veterinary diclofenac use. Buechley says the numbers of vultures have stabilized, and are now showing signs of slowly increasing.

Now, the center of the vulture crisis is in sub-Saharan Africa. “In Africa, it's a lot more challenging,” Buechley says. “It's a darker story.” Potent newly affordable poisons are used to control predatory pests, such as lions or jackals. The poisons are so toxic that they can cascade through ecosystems: birds, mammals and insects are often found littering the area around these poisoned carcasses. But, as the predominant scavenger, vultures take the brunt of the poisoning and face the largest number of casualties. For example, an elephant carcass poisoned in Namibia in 2007 killed as many as 600 vultures. In other cases, vultures are the victims of poachers who poison carcasses so that vultures do not give away the location of illegally taken animals. “Vultures are taking the hit, indirectly, for a lot of this human-wildlife conflict, as well as the illegal trade in animal parts,” Buechley says. This crisis, unfortunately, is ongoing.

Rise of the facultative scavengers In vultures’ absence, other scavenger populations increase to take advantage of all of the uneaten carrion. By some estimates, in Central America, South America and Africa, vultures eat more meat than all predators combined. Without vultures, animals that eat carrion as a part of their diet (called facultative scavengers, as opposed to vultures, which eat only carrion) proliferate to take advantage of the available nutrients in a dead carcass. “There are a ton of nutrients in carrion that are going to be taken advantage of by something,” Buechley says.

Crows, rats, dogs — any of these species can suddenly become abundant and dominant, to the point of crowding out the remaining vultures. Hundreds of vultures on a carcass can easily frighten away packs of dogs, Şekercioğlu says. But when only a few vultures are left, the dogs can rule.

Such changes in populations of certain animal groups can upset the balance of food webs. “All these facultative scavengers are also predators, and so they also go out and eat other organisms too,” Buechley says. “You have this cascading effect.”

Human impactsThe impact of vultures’ declines are not limited to the realm of ecology, however. Vultures are highly efficient consumers of carrion, sometimes locating and consuming carcasses within an hour, before other forms of decay can set in. And vultures’ stomachs are highly acidic, killing nearly all bacteria or viruses that may be present in carrion. Combined with the fact that vultures rarely come in contact with humans, vultures serve as a barrier to prevent diseases from proliferating in dead animals and spreading to humans. Other facultative scavengers are not so adapted, and could pass along those diseases into human populations, as many are already fixtures in cities.For example, following the decline of vultures, India experienced a strong uptick in feral dogs —by an estimated seven million. The increase in dogs, potentially feeding on disease-ridden carcasses, is thought to have at least partially caused the rabies outbreak that was estimated to have killed 48,000 people from 1992-2006 in India — deaths that may have been avoided if not for the disappearance of vultures.

Members of the Parsi sect of Zoroastrianism experienced a different impact. For thousands of years, the Parsi people have placed their dead on exposed mountaintops or tall towers for vultures to consume. The practice is called “sky burial.”

But with few vultures and unable to properly handle their dead, the Parsis experienced a crisis within the faith. Some constructed captive vulture aviaries. Others talked about desiccating bodies using focused solar mirrors. The Parsis’ plight exemplifies the vultures’ role in south Asian society — and the various impacts if the vultures aren’t there.

Learning from the pastAlthough the vulture crisis in Africa is ongoing, Buechley and Şekercioğlu can predict what the outcome will be, based on previous experiences in India. Crows, gulls, rats and dogs will boom. And the rabies outbreak in India may just be a prologue, because several sub-Saharan Africa countries already have the highest per-capita rabies infection rates in the world. Rabies is only one of the many potential diseases that vultures had helped regulate.

Buechley notes that the poisoning that is killing vultures is also affecting many other organisms throughout ecosystems. But vultures are the most sensitive canaries in ecological coal mines. The story of the California condor shows that recovery is possible, but at a high cost that countries in the developing world may not be able to pay.

“It's good news and bad news,” Şekercioğlu says. “It shows that we can bring back these scavengers. But the bad news is that once we get to these numbers, it costs tens of millions of dollars and decades to bring them back. You don't want to go there. And once you go there, we can afford to save only a few species.”

So, Buechley argues, “the better solution is to invest in vulture conservation here and now, in order to stem incalculable damage from trophic cascades and increased human disease burden in the developing world.”

The study was funded by a National Science Foundation Graduate Research Fellowship and by the University of Utah's Global Change and Sustainability Center.


Watch the video: Vultures: The acid-puking, plague-busting heroes of the ecosystem - Kenny Coogan (August 2022).