In the world there are 22 species of vultures which are predominantly found in the tropical and subtropical regions. The vultures belong to order Accipitriformes which contains two families namely Accipitridae (Old World vultures) and Cathartidae (New World vultures).
The New world vultures have featherless head and necks which allows the vultures to reach inside the carcasses without the head and neck portion getting drenched with blood, which can cause bacterial infection.
Many vulture species have large pouch located in the throat region which is used to store food, an adaptation to famine and scavenging lifestyle. The beak is exceptionally strong and heavy used for tearing skin, muscle and bones. The eyes are well developed and used to scout for carcasses during floating flight actions at noon.
Vultures are the only known obligate scavengers. They rarely attack healthy animals, but may kill the wounded or sick. When a carcass has too thick a hide for its beak to open, it waits for a larger scavenger (for example Hyena, Jackals and Wild Boars) to eat first.
The dead and decaying flesh acts as a breeding ground for infectious disease-causing bacteria which spread via insects. Since Vultures feed on such flesh, the bacterial transmission and disease spread is controlled.
Breeding in Vultures
When compared with other Accipiter, vultures take time to mature, which is around 4-6 years old. The breeding is also slow and just lay one egg in each clutch (although Egyptian vultures may lay 2 to 3 eggs a year). Vultures are colonial breeders and prefer rocky cliffs and tall trees for nest building. The nest usually consists of sticks lined with green leaves and is used for many seasons until it is damaged.
Vultures are monogamous (except for Egyptian vultures where extra pair copulations are observed, females sometimes associate with other males which provide help in raising the young) and all species show almost no sexual dimorphism. Both sexes are equally responsible for raising the young ones and taking care of the nests.
Breeding season in India is observed in spring which starts from February end. After copulation the egg is laid which is incubated for approximately 35-42 days. The availability of adequate food ensures successful breeding.
India: Vulture’s paradise
India’s population is around 80% Hindu, which do not consume cattle meat as they are considered sacred due to religion. These religious beliefs actually act in favor of the vulture population, as the carcasses of cattle are left in the open field for the vultures to consume.
Not only Hindus, but Parsis also help the vulture populations by basically not cremating or burying the corpse, as both these acts are considered sacrilegious. Upon the death, the corpse is placed on the Tower of Silence which is then consumed by the vultures. As per the religious beliefs, the vultures act as an intermediate between earth and heaven and basically liberate the soul upon consuming the corpse.
Decrease in Vulture populations
From early 80s till now, the vulture population has decreased by 95%.
This decrease is tracked back to mid-80s when the farmers around the world started heavily relying on 'Diclofenac', used as an anti-inflammatory drug to treat livestock's fever, inflammation, fever and pain. When carcasses of such livestock were consumed by the vultures it caused infertility and heavy dose caused death.
Dr. Lindsay Oaks and his team at The Peregrine Fund found out that diclofenac was the reason which caused decrease in the vulture population. Around 2003 the decrease in vulture population was also noticed by the Bombay Natural History Society, and the pressures from BNHS as well as International scientific community pressurized the government and thus veterinarians banned the use of Diclofenac in India since 2006.
Effects on ecosystem due to decline in the population of vultures
In the ecosystem vultures acted as a natural animal disposal system as they consumed the rotting carcasses. But due to sudden disappearance of vulture populations, these carcasses became an easy feeding opportunity for feral dogs and rats.
This led to increase in the feral dogs and rat population, which were basically carriers as they were transmitting disease (for example plague, anthrax, and rabies) causing pathogens to humans causing large scale deaths. Vultures on the other hand are equipped with efficient metabolism which basically destroy such pathogens, eliminating diseases all together.
Due to increase in the feral dog populations (India is currently home to 18 million dog populations), Leopards started invading human settlements as these dogs are easy prey for them. This results in human-animal conflict and are detrimental to both the animal as well as humans.
Moving forward
Upon finding the reason for vulture decrease, diclofenac was banned from veterinary use on March 11, 2006. This ban was followed shortly by other countries like Pakistan and Nepal which are home to many vulture species as well.
A replacement drug known as ‘meloxicam’ was developed which produced the same action on livestock but showed no ill-effects on vultures.
The ban on diclofenac and with protection laws in action, the current vulture population seems to be on the rise and estimated to grow by 20% over next 5 years.
Vultures of Sariska
Sariska is an enchanting place located in the Alwar district of the state of Rajasthan. The landscape of Sariska includes hills and narrow valleys of the Aravali Mountain range.
The forests of Sariska constitutes of grasslands, dry deciduous forests, tropical forests, and scrub- thorny arid forests. The climate of Sariska includes distinct winter, summer, monsoon and post- monsoon seasons with an overall subtropical climate.
The climate and topographical terrain of Sariska provides an abode for 6 vulture species out of which some are resident whereas the other are winter migrants which visit India during the months of December, January and February from Northern regions of India (Himalayas), Pakistan, Afghanistan, Kazakhstan, and Mongolia.
1. Indian Vulture (Gyps indicus) Family: Accipitridae (Old World vultures) IUCN status: Critically endangered Resident to Sariska region Length (L): 92 cm; Wingspan (WS): 200-250 cm
2. Egyptian Vulture (Neophron percnopterus) Family: Accipitridae (Old World vultures) IUCN status: Near threatened Resident to Sariska region Length (L): 65 cm; Wingspan (WS): 150-170cm
3. White-rumped Vulture (Gyps bengalensis) Family: Accipitridae (Old World vultures) IUCN status: Critically endangered Resident to Sariska region Length (L): 85-90 cm; Wingspan (WS): 195-210 cm
4. Cinnerous Vulture (Aegypius monachus) Family: Accipitridae (Old World vultures) IUCN status: Endangered Winter migrant Length (L): 100-105 cm; Wingspan (WS): 250-310 cm
5. Red-headed Vulture (Sacrogyps calvus) Family: Accipitridae (Old World vultures) IUCN status: Critically endangered Resident to Sariska region Length (L): 84 cm; Wingspan (WS): 200-230 cm
6. Eurasian Griffon Vulture (Gyps fulvus) Family: Accipitridae (Old World vultures) IUCN status: Least concern Winter migrant Length (L): 100 cm; Wingspan (WS): 235-270 cm
Blog by Mr. Kushagra Gupta and Mr. Aakash Upare, Naturalists at Utsav Camp Sariska.
