Meet the Species

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California’s Wonderful Wildlife

Vultures

Why Care?

We care, if we think about it, because vultures in flight lift our hearts. Even folks grossed-out by their eating habits admire their soaring flight. But what most of us don’t see is how much we need them. In this bizarre world of ours, all animals must eat other living beings. A great many animals die every day, and their bodies are eaten, and so the cycle of life and death goes on in a fairly tidy fashion. The vulture is one of the most important actors in this process.

We tend to think this cycle is one of victims, predators. But far more creatures die than are killed by predators, more even than predators and microbes and parasites all together can take care of quickly. Hence the need for scavengers. Someone who will come along and clean up the land.

Indeed, without scavengers, this would be a smelly old world indeed. Among in the system of the clean-ups, birds reign. They can cover much more territory and find carcases more quickly than mammals; they attract other scavengers, bird and mammal alike, because they are so visible. And their food is almost entirely carrion, whereas mammalian and reptilian scavengers often kill prey as well. The system works like a charm.

Or it did for millions of years. But today there is a problem: For twenty or so years, many of the Old World species have been seriously declining, some to near-extinction. Thanks to the Peregrine Fund, we know that the major reason for this is a drug used to reduce pain and infection and enhance growth and production in Asian domestic animals. Dicoflenac, a non-steroidal anti-inflammatory agent, was given to nearly all the cattle in India and nearby countries. When these cattle died – that is, when they were not slaughtered and carried off to be rendered into meat or leather – they were left, as is the tradition in those countries, for the vultures to clean up. The vultures ate the carcases, and ingested the residue of the drug. But their systems couldn’t tolerate it, and they died of kidney and liver failure. Millions of Asian vultures have died. The population of several species has either dropped to a dangerously low level, or has already dipped below the horizon.

In 2006, the Peregrine Fund convinced part of Pakistan to ban dicoflenac, and in the years since then, several species of vultures have begun an impressive recovery. The drug is still in use in other places, however. And in human patients. Even if it were banned today, the vulture populations in many areas would take decades to recover. Some would never make it. Most vultures need 3 to 7 years to reach breeding age, and lay only a couple of eggs a year. The equation doesn’t inspire great hope.

Meanwhile, the problems of disease and fouled air are spreading as the vultures die. Town dumps that were once kept clean by flocks of vultures are now stinking pools, haunted by feral dogs and other mammalian scavengers. Rabies is increasing among humans in those areas, since mammals are a reservoir of that deadly virus. This is a problem that biologists and ornithologists across the world are working to solve.

Most of our New World Vultures, fortunately, are holding their own, doing their traditional job of clean-up – though even prehistorically, we have never counted on them as our main sanitation crew. Central California is home to two species, the Turkey Vulture (Cathartes aura), very common in our area, and the California Condor (Gymnogyps californianus), a prehistoric giant still with us thanks to vigorous protection and a breeding-release program. It is one of the rarest birds on earth today. The fact that it is on the increase, however slight, gives hope that the Old World Vultures declining today may yet turn around.

New World Vultures 

There are more than twenty species of vulture in the world. Our seven New World species are not closely related to their Old World counterparts, those huge, squabbling scavengers we see in films about Africa and Asia. The two groups seem to have developed separately in a process known as “convergent evolution” – that is, unrelated species developing similar physical characteristics in order to inhabit similar environmental niches.

Vultures are called “raptors,” though our New World species seem not to share important genetic traits with hawks and falcons, or owls, or even Old World vultures. But “raptor” is actually a label we use to discuss as a group a broad collection of similar birds living similar lives. Vultures, however, lack one key “raptor” characteristic: the word “raptor” comes from the Latin word “rapere,” “to seize,” indicating that these birds kill their prey with their feet. However, no vulture has a killing foot, with those eagle-like razor talons; most don’t kill at all, and none ever with their feet.

 

Raptors Have Killing Feet: We Ask School Children: Can This Foot Kill?

 

 

The True Killer’s Foot – Golden Eagle, Quintessential Raptor

All vultures do share traits that enhance their carrion-eating habits, no matter what their developmental background. They have keen eyesight; featherless heads and long, bare necks for reaching into body cavities; a digestive system capable of coping with dangerous bacteria; beaks designed for tearing time-softened flesh; weak, flat feet more suited for walking than grasping; and short toes with blunted talons. The Cathartes vultures – three related species in North and South America, including our Turkey Vulture – also have a highly developed olfactory or smelling system. But the other species in North and South America, the Black and King vultures and the Condors, do not. And neither do any of the Old World species.

Central California is home to two species, the familiar Turkey Vulture (Cathartes aura) and the California Condor (Gymnogyps californianus), a prehistoric giant and one of the rarest birds on earth today.

Turkey Vulture (Cathartes aura, golden purifier). Partially migratory. Turkey Vultures that summer in our high country may gather in large “kettles,” or flying groups, and come to lower elevations, or even migrate to South America in the autumn. But except in cold areas, some part of the local population remain in place year round. These scavengers have a highly acute olfactory system, which seems to be rare among raptors – indeed among birds in general (other birds with good “smellers” are albatrosses and tubenoses who wander the northern seas and feed on fish, and kiwis. Also some nocturnal birds). The Turkey Vulture has noticeably open nares – you can see right through the septum – and these “collect” and transfer minute odor signals to a large olfactory center in the brain. In comparison, the Black and King Vultures and the two condors show a very modest nostril and no signs that they are finding food by smell.

We do know for a certainty, however – after centuries of argument – that the Turkey Vulture does locate food by odor. This has been tested and photographed, and we have also the evidence of other scavengers following it to food.

Adult Turkey Vultures eat all sizes of carrion, from small lizards killed on the road, to horses and cows dead in fields. They feed communally and roost in sometimes large groups. In these great roosts, they can become a nuisance – who wants a few dozen vultures perching on his roof? Once ensconced they can be hard to drive off.

In breeding season, however, pairs leave the group and nest secretly in caves and hollow logs or under cliff ledges. They lay perhaps two eggs a year, and bring food to their young in their crops, regurgitating it for the chicks. The chicks are surprisingly charming, covered in fluffy white down and with glossy black faces and alert dark eyes.

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TUVU head for web

Adult Turkey Vultures (above, lower photo) have red, featherless heads (which make them look a bit like Turkeys, hence the name) and beaks as white as bone. Immature ones  (above, upper photo, nestling) have dark heads and beak tips. During the first two years, the head and beak slowly metamorphose from very dark to gray, to adult red with the white shining beak. (The photo at the top of the page is of a fledged juvenile, whose face is beginning to show red. The metallic gray and even the final red, when marked with occasional white crusting – rare in our California birds, give the creatures a prehistoric, almost monstrous look.) Young Turkey Vultures remain with their parents and natal flock until they are fully grown; many of them stay all their lives. Since these birds are not hunters, but gatherers, so to speak, there is very little competition over food or territory, and vultures show a strong social tendency.

Adult Turkey Vulture

Turkey Vultures are master flyers, soaring on thermals and swooping in aerobatic loops. They can travel 100 miles or more in a day by “riding” the thermals – spiraling up on a column of warm air, then angling down at speed until they find another warm column to begin the cycle again.

Larger than hawks, smaller than eagles, the Turkey Vulture can be best identified by the silvery underwings, which contrast with their dark bodies. In flight, these birds tilt back and forth, their wings in a V. We sometimes call them “buzzards,” but that is really the name of Buteo buteo, the European cousin of our Red-tailed Hawk. Early settlers saw a big dark bird, and thought it was the familiar one of the homeland they had left behind.

California Condor (Gymnogyps californianus, naked-headed vulture from California)Year around. With a 9-10 foot wingspan and a weight of about 30 pounds, this is one of the largest flying birds in North America today. Condors are unmistakeable – enormous black birds with fleshy red faces and white wing patches. Most have a large numbered wing-tag on the patagium, put there by scientists to identify individual birds.

Living for millennia throughout the continent – their bones have been found from East Coast to California – condors declined at the end of the Pleistocene with the die-off of the giant mammals on whose carcases they had fed. In historic times, a few were still surviving in California and the Southwest, particularly wherever herds of bison or elk were common. But by the 1980s, there were few great herds and the birds were doomed to extinction. In 1985, in a daring and controversial move, scientists in Southern California captured the few remaining individuals and entered them into a breeding program.

The plan succeeded, with some glitches, and today condors are being reintroduced into California and Arizona. There is still no viable breeding population in the wild – condors don’t breed until about 6 years of age, and then lay only one egg every two years, so a low mortality rate is vital. The first group of released young birds all died, mainly from the ills of social ineptitude, which led them into conflict with humans or human materials. We are now releasing some of the original adult condors with the young ones, to teach the kids a few tricks of survival. But today young and adults alike, along with other scavengers, are dying of lead poisoning, from the shot animals they feed on. California is phasing out lead ammunition in an effort to avoid killing our clean-up crews, but it will be years before that process is complete. Meanwhile, all condors we can see today have been bred in captivity.

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Adult California Condor

Other important hurdles for sustaining a condor population are food and space. Condors feed communally on large carcases and roost in groups. And because they are so big, they need high points and powerful updrafts to get and stay aloft. They do well along the empty stretches of the California Coast, where the sea winds are brisk and large dead marine animals wash ashore. You can see them off Highway 1 below San Francisco.

Vultures & Us

From our beginnings, we humans have made use of the vulture’s skills and its other-worldly aura. Our scavenging ancestors probably followed the birds to food, and in many of our oldest mythologies, the vulture carried our souls to the next world.

As time went on, the bird’s role expanded. In Catal Huyuk, in Turkey, the earliest city we have yet uncovered, 8,000-year-old wall art and stone carvings show clearly that vultures were invited to dispose of human bodies in ceremonial places. Other cultures reveal similar practices, or made the vulture a part of their religious rituals. In ancient Egypt, vultures appear on tomb walls and even on the great double-crown of the Pharaohs. Below is a vulture jewel from Egypt.

In Europe, the beautiful Bearded Vultures (who have feathers on their heads and necks and who decorate their breast feathers with red clay) have figured in mythology. The Greeks, taking elements of older stories, believed that Zeus sent them to punish the Titan Prometheus for giving humans the gift of’ fire. Two Bearded Vultures came daily to feed on his liver.

In California and South America, condors in prehistoric and early historic times figured in the ceremonies of many societies. Flutes made of condor wing bones are common finds in archeological sites in the Andes, and their feathers were used in ceremonial clothing. Some tribes in both continents would capture young birds for use in their rites. Sometimes the birds were released afterwards, perhaps as messengers to the spirit world. But many were killed and their bodies preserved.

Today, in Asia, the massive vulture die-off is posing a cultural dilemma for Zoroastrians, who believe burial and cremation pollute earth and air. For centuries they have counted on vultures to properly dispose of their dead on the Towers of Silence. Some Tibetan Buddhists also use the birds in similar rituals. And there are no longer enough vultures to perform these services. The problems pf vulture survival are not just biologic, but social as well.

Drawing of a Vulture Panel from Catal Huyuk, about 8,000 Years Ago

 

In the United States and Canada, more prosaically by far, several gas companies use Turkey Vultures to find leaks in commercial gas lines. The gas in these pipes is perfumed with ethyl mercaptan, the same odiferous chemical emitted by decaying carrion. Turkey Vultures find the leaks quickly and soar above them, looking for the dinner that has been so effectively, if falsely, advertised.

Curious Facts about Turkey Vultures and California Condors

Turkey Vulture:

Turkey Vultures vomit easily and use this as a defensive mechanism. Or to lighten the load, as it were, if they need to take flight quickly.

Turkey Vultures often open their wings in the early morning and face the sun. They are probably warming their muscles preparatory to flight.

Only the Turkey Vulture and its two South American cousins, the Greater and Lesser Yellow-headed Vultures, have the capacity to locate carrion by odor. How far away they can detect carrion we don’t know – it is dependent on many factors, such as wind and so on. So far, they have found hidden carrion in research studies from more than 3 miles away. Some gas companies depend on Turkey Vultures to alert them to a gas leak in the pipelines. The gas is “perfumed” with ethal mercaptan, the same chemical released in decomposing carcasses – and the vultures congregate over the spot, thus leading pipeline repair crews to the correct spot.

The Turkey Vulture and all New World Vultures are different in many physical ways. The differences are largely genetic, for they all have developed a similar package of behaviors and physical traits that enhance their carrion-eating life style. One interesting difference: Old World species have a syrinx (voice box) and can make complex sounds; in the New World – no syrinx, so they can only hiss or groan.

Turkey Vultures have been observed eating the eggs of ground-nesting birds. They will sometimes eat garbage.

Turkey Vultures often urinate onto their legs, giving the red skin there a whitish cast. This habit (urohydrosis) is thought to cool the featherless legs, hence cooling the entire body as the urine evaporates. It is also very acidic and kills bacteria the bird may have picked up walking on its dinner.

Urohydrosis may also have something to do with the vulture’s keen sense of smell, but this is speculation.

One Turkey Vulture in captivity was reported to have identified one of his caretakers by odor. The man’s wife wore his jacket near the cage one day, and the vulture greeted her in the same special way he always greeted his caretaker.

California Condor:

Condors have the longest wingspan of any bird in the US.

Most condors today are still bred in captivity. The released birds are monitored by scientists, tested for lead in the blood, treated when necessary.

These birds are so large, they sometimes cannot take off from the ground, and have been reported laboriously climbing hills to get to a launch site.

Young condors are curious and unafraid, and have been known to break into people’s houses or perch on roofs and railings. Wild-bred condors and youngsters who are released in the company of a once-wild adult, have better manners.

At Grand Canyon in the late 1990s, released condors would sometimes dive past visitors on the South Rim, looking them over.

You can see condors on Highway 1 south of San Francisco in the area of Big Sur.

You can buy a film about the latest chapter in the story of the Condor’s come-back, The Condor’s Shadow, at theCondorsShadow.com

 

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