• by Dr. Sarah Oktay, Director, University of Massachusetts Nantucket Field Station •
This week’s topic came up while talking with friends about trends on island that might be fun to write about. They mentioned that they remember when no Turkey Vultures were present on island and how prolific they are now. Doesn’t everyone have carrion eater conversations during dinner? On Nantucket that may be more common, our food is so good even talk of road kill doesn’t deter us from eating. And my friends were right, Turkey Vultures on Nantucket are a relatively recent immigrant, lured north by warming weather and into urban and semi urban areas with the growth of streets and highways. Along with crows, they are frequently encountered on our roads cleaning up road kill created when wildlife travel meets car travel. Both deserve their own column because they are fascinating birds, so let’s learn more about Turkey Vultures, “Turkey Buzzards” or TVs as they are often called for shorthand. I’ll also capitalize Turkey Vulture after reading a few articles which insist that is the way to do it properly. On May 25th, the Sunday morning bird walk (which resume in September) found 12 Turkey Vultures just in the Crooked Road and Cliff Road area (checklist at http://ebird.org/ebird/view/checklist?subID=S18551931). On any given day on Nantucket there are likely several dozen flying around.
The Turkey Vulture’s Latin name, Cathartes aura, comes from the Greek “katharsis” meaning to purify or to cleanse and “aura” Latinized from the Native Mexican word for the bird, “auroura”. The Turkey Vulture was first formally described by Linnaeus as Vultur aura in his Systema Naturae in 1758; “vulture” is derived from the Latin word “vultures”, meaning “tearer” which alludes to their feeding habits.Turkey Vultures are New World Vultures, found in the Americas. Though both are similar in appearance and have similar ecological roles, the New World and Old World Vultures evolved from different ancestors in different parts of the world. Just how different the two are is currently under debate, with some earlier authorities suggesting that the New World vultures are more closely related to storks. Most authorities now place Turkey Vultures in their own order, Cathartiformes although others, especially in South America, prefer placing them in the Order Incertae sedis, or Falconiformes. Riveting. Keep reading, TVs do many cool things.
The Turkey Vulture breeds from southern British Columbia, central Saskatchewan, the Great Lakes, and New Hampshire southward. It winters in the Southwest, and in East northward to southern New England http://birds.audubon.org/birds/turkey-vulture retrieved June 1st, 2014. “Turkey vultures, so named for their featherless headed resemblance to Wild Turkeys and their habit of sitting on the ground to eat, are migratory in nature but winter as far north as Connecticut. They appear in Massachusetts in late February and slowly make their way north for a summer spent wavering over farm fields and eating carrion.” http://thedailybirdnewengland.blogspot.com/2011/02/signs-of-spring-vulture.html
Both male and female TVs are very similar in appearance exhibiting minimal sexual dimorphism with the only differences being that the female is slightly larger and the males have a wattled (fleshly and wrinkly) look. Their bodies are very dark brown, nearly black and they have the characteristic bald, pink heads with a sharp, whitish, hook-tipped bill. Their legs and feet are reddish pink (often stained white, we’ll learn why soon!) and their wings are two-toned from below with dark inner wings and paler almost silvery outer wings. The juvenile have grayish heads and feet. They weigh in average about 64 ounces (almost 4 pounds or roughly 2 kilograms) and vary in length (height) from 24-32 inches with a total wingspan of 63-71 inches,
Turkey Vulture’s have a semicircular pattern of whitish to greenish papillae or warts around their eyes that varies from one individual to another. These papillae may be caused by bacterial infections resulting from constant exposure to rotting meat. This gives them a “Mr. Burns” look if you remember your Simpson’s characters. The nasal septum, a thin partition between the two nostrils, has a hole in it (this is true of all New World vultures), so an observer can look right through a Turkey Vulture’s nostrils. That means that “a Turkey Vulture, should it be so inclined, can wear a nose ring.” I wish I had thought of that line, but that is from http://www.wingmasters.net/tvulture.htm retrieved June 1st, 2014.
The Turkey Vulture’s return to New England is a sure sign that things will get warmer. Like Storks, the Turkey Vulture often defecates on its own legs, using the evaporation of the water in the feces and/or urine to cool itself, a process known as urohidrosis (sounds lovely). Pooping on itself cools the blood vessels in the unfeathered tarsi and feet, and causes white uric acid to streak the legs. The Turkey Vulture has few natural predators. Adult, immature and fledging vultures may fall prey to Golden Eagles, Bald Eagles and Great Horned Owls, while eggs and nestlings may be preyed on by mammals such as raccoons, opossum and foxes (which are not found on Nantucket). Its primary form of defense is regurgitating semi-digested meat, which deters most creatures intent on raiding a vulture nest. Even fledglings can projectile vomit in order to protect themselves. The Turkey Vulture lives up to 16 years in the wild and 30+ years in captivity (derived from http://en.wikipedia.org/wiki/Turkey_vulture retrieved June 1st, 2014.)
Often people will mistake a Turkey Vulture for a hawk. Many raptors exhibit the same kind of thermal flying or circling behavior, but unlike an Eagle or Red-Tail Hawk, TVs have a wobbly look as they circle. They can also be identified by the V pattern (dihedral) they make while flying and by the fact that their feather tips are spread out almost like fingers. In flight the outermost six primary feathers are splayed open like the curved fingers of a hand to give the bird more lift. Because these primary feathers can be moved individually, this species has superb flight control. A turkey vulture can stay aloft at very slow speeds without stalling and falling. They prefer to ride thermals and are less likely to be seen on windless days. They are also bigger than other raptors except for Eagles and Condors.
Turkey Vultures are relative new comers to upper New England. They were seen as occasional migrants for decades but did not hang around to nest until recently. “In 1930 a Turkey Vulture nest discovered in Connecticut marked the species’ first confirmed nesting in New England. Turkey Vultures nested in Massachusetts for the first time in 1954, and now they are firmly established in the state as both breeding birds and migrants. By the early 1970s they had pushed into New Hampshire and by the early 1980s they could be seen in Maine.” From http://www.wingmasters.net/tvulture.htm retrieved June 1st, 2014.)
Designed to eat carrion (dead things) TVs have an acute sense of smell and can reportedly smell day old meat from several miles away. A lot of research has been done to evaluate the acuity of a Vulture’s sense of smell . John James Audubon himself had difficulty verifying their abilities because he used carrion that was too far gone to interest a Turkey Vulture. Ecologist David Houston, working in the tropics, hid chicken carcasses in varying stages of decay. His research showed that turkey vultures cannot detect freshly-killed carcasses by smell. By the second or third day, as the meat begins to rot, the birds can, and do, find their way to the carcasses. However, by the fourth day, when the chickens were in an advanced state of decay and therefore very smelly, turkey vultures rarely showed any interest. Houston concluded that by that point there would be such a high level of microtoxins present in the putrescent meat that it would be dangerous to eat even for a vulture.
This is not to say that Turkey Vultures hunt exclusively by smell. They use an efficient combination of sight and smell. This species typically soars about 200 feet in the air or even lower, cruising just above the treetops. At that height the birds can smell a carcass, but not higher. On these searching flights the vultures are also using their very sharp eyesight to spot food. Once it is sighted, another vulture strategy comes into play. These birds watch each other as they look for food. When food is sighted, the finder wins a prize (just kidding, well they do get to eat) then circles above it for some time, alerting the other vultures in the vicinity to the presence of a meal. When one bird drops down, they all drop. Last one to the carcass is a rotten egg, or at least smells like one.
Fortunately, the current population of Turkey Vultures which has protected status as a migratory bird now exceeds five million birds. Most populations of this adaptable species appear to be thriving. The vulture’s beneficial role as a scavenger is recognized, and the species is not persecuted. Unfortunately, this was not always the case. In the past, Turkey Vultures were shot because ranchers and farmers mistakenly believed that they spread diseases and contaminated watering holes for livestock, although there is no evidence to substantiate this claim.
Last but not least there are many legends and myths and stories associated with Turkey Vultures. For instance, I found this story: “In American Indian mythology, it was believed that the sun was originally much closer to the earth and was in danger of burning it up. First the fox unsuccessfully tried to pull the sun away in its mouth, accounting for the black inside of its mouth. Next the opossum unsuccessfully tried to pull the sun away with its tail, accounting for the hairless tail. Finally a beautiful fully feathered vulture successfully pushed the sun away from the earth with its head, thus becoming bald for eternity” from http://www.pauldfrost.co.uk/intro_v.html retrieved June 1st, 2014. Not only do they keep our roads clean, but they also managed to save the world, good for them. This article just covered the tip of the iceberg on TVs I encourage you to learn more. This site is an excellent source of information on both Turkey Vultures and Black Vultures: http://www.wingmasters.net/tvulture.htm. I also really appreciated the Hawk Mountain info at http://www.hawkmountain.org/raptorpedia/hawks-at-hawk-mountain/hawk-species-at-hawk-mountain/turkey-vulture/page.aspx?id=644. “Notes on the Taxonomy of Vultures” by American Ornithologist Dean Amadon can be found at (http://sora.unm.edu/sites/default/files/journals/condor/v079n04/p0413-p0416.pdf), Upon his death, his estate created a grant for raptor research which can be found at http://www.raptorresearchfoundation.org/grants-and-awards/grants/dean-amadon-grant