By Jennifer Nixon, Denver Zoo Bird Keeper
Meet this week’s feathered friend - Big Irv, a Cinereous vulture (Aegypius monachus) that lives with his mate in the Nurture Trail in the yard closest to Lorikeet Adventure.
Big Irv is 24 years old and was born in South Carolina and was moved to Denver in 2010. He weighs around 15 pounds which is much smaller that his mate who weighs around 26 pounds. It is common in raptor species for females to be larger than males, although no one is sure why. One suggestion is that females spend more time on the nest and so they are bigger to be better able to protect it.
Big Irv enjoys eating lots of meat and gets a varied diet at the Zoo to satisfy his needs. He also enjoys building nests, which is why he can often be seen carrying sticks around his exhibit.
Cinereous vultures are able to fly at very high altitudes thanks to characteristics of their blood that allows them to absorb oxygen very efficiently. One Cinereous vulture was seen flying at a height of over 22,000 feet on Mount Everest.
Cinereous vultures in the wild live all across Southern Europe and Asia, but despite their huge range, they are listed as Near Threatened by the IUCN Redlist. One of the problems that Cinereous vultures face in the wild is that they are scavengers who eat carrion (dead animals), and in the modern world dead animals tend to get disposed of in the interest of good hygiene and not left lying around to be eaten. Another threat is ranchers using strychnine and other poisons to keep predators away from livestock. The vultures then eat the dead predators or the poisoned carcass and ingest the strychnine accidentally. Sometimes ranchers also wrongly persecute them because they think the vulture will eat their livestock. This is not true since the vultures mainly feed on already deceased animals. They are actually serving an important role in the recycling of animal material because they are consuming the meat before it can rot.
Poachers are also responsible for vulture deaths because they fear the vultures will “give them away” to rangers and other law enforcement as they illegally hunt wild game. Another source of poisoning is from ranchers and game farmers who shoot their animals to legally sell the meat. They leave some of the carcass behind and the vultures eat the leftovers and consume the lead fragments from the ammunition. The vultures then face potential lead poisoning, which can lead to death.
In Mongolia, Denver Zoo has a conservation biology project studying the migration of Cinereous vultures. Denver Zoo is also involved in a conservation project in Botswana with lappet-faced vultures documenting the impact of poisoning on the vultures. These are just some of the ways that Denver Zoo is supporting wild vulture populations through conservation biology projects across the globe. Learn more about a recent fundraiser to help create “vulture restaurants” in Botswana where zoo staff and supporters rode in an incredible bike race in South Africa.
Cinereous vultures tend to live alone or in pairs, but will feed together in large groups. They nest high up in trees or on cliffs, and produce one egg which they both will incubate for 50-54 days. Big Irv and his female have produced a few eggs over the years, but none have been fertile. They are currently sitting on a wooden “dummy” egg in the corner of the exhibit. The real egg is in the Avian Propagation building in an artificial incubator awaiting determination of fertility. Cross your fingers for a fertile egg! You can visit them and see a vulture nest up close and personal since it is right up next to the front of their yard. But, please keep your distance and respect the vultures nesting area – we want to keep it quiet while they are nesting.