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TURKEY VULTURE

AMERICAN VULTURES

Family Cathartidae

     The vultures of the Old World (such as the one pictured below) are not at all related to New World vultures.

african vulture african vulture
     While Old World vultures are raptors related to hawks and eagles, it seems that New World vultures are actually more closely related to storks, such as those pictured below.  New World vultures should be classified with storks in the order Ciconiformes. A number of anatomical features link storks and New World vultures. The relationship between New World vultures and storks is suggested by genetic evidence as well as by a number of anatomical features shared by New World vultures and storks which set them apart from raptors (a raised hind toe, the nature of the nostrils, the lack of a syrinx for sound production, and a good sense of smell).  New World vultures also excrete onto their own legs as a cooling mechanism, as do storks.  Like storks, New World vultures do not build nests. Some storks are primarily scavengers. A fossil bird named the “stilt vulture” (Neocathartes grallator) seems to be related to vultures but possessed long legs like a stork (Weidensaul, 1996; Houston, 2001). black vulture foot
stork stork

Vultures are the most abundant raptor. There are 22 species, including 2 species of condor. African vultures can fly at heights of 15,000 feet when traveling long distances. The bare head of vultures also helps them to lose heat. Vulture feet are adapted for walking and are very different from that of raptors ( Houston, 2001). Soaring requires only slightly more energy than standing still and allows vultures to search large expanses for carrion ( Houston, 2001).New world vultures can live up to 45 years and do not breed until they are 6 to 8 years old (Sibley, 2001). About a third of the species of vulture are in decline ( Houston, 2001).

The family Vulturidae (also known as Cathartidae) is composed of 7 species of New World Vulture: turkey vultures, yellow-headed vultures, greater yellow headed vultures (all classified in the genus Cathartes), black vultures, king vultures, California condors, and Andean condors. Fossil relatives included six extinct genera of condors (Breagyps, Hadrogyps, Pleiogyps, Geronogyps, Aizenogyps, and Dryornis) whose oldest fossils are dated from the Mid-Miocene and a number of fossil vultures (the oldest of which are known from the Old World) dating from the Late Eocene/Early Oligocene. Some researchers include the giant extinct teratorns (Argentavis and Teratornis) as members of the family Vulturidae while others classify them as their own separate family Teratornidae which was equally related to both New World vultures and storks (Snyder, 2000).

The Pleistocene range of the California condor stretched eastward to include Texas, Florida, and New York. California condors can reach 8.5 kg in weight (just slightly lighter than some turkeys and trumpeter swans) with a wingspan of ten feet. Condors once ranged throughout North America and stretched eastward into New York and Florida. In 1987 the California condor population was reduced to 27 birds ( Houston, 2001). It is estimated that there were about 150 California condors alive in 1950, 60 in the late 1960s, and the population dropped below twenty in the early 1980s. One of the major causes of their decline was the contamination of the carcasses they fed on by the lead shot used by hunters. At that point birds were captured to initiate a captive flock. The releases into the wild occurred in 1992 and almost twenty had been released by 1999 (Snyder, 2000).

      The first vultures in the fossil record appeared 40,000-50,000 years ago and spread throughout the world soon afterwards. The spread of large mammals upon which they fed undoubtedly contributed to their success.New World vultures once spread into the Old World ( Houston, 2001). Enormous fossil vultures are known from North and South America.  Teratorns such as Teratornis merriami and Teratornis incredibilis from North America had wingspans of 12 and 16 feet while Argentavis magnificens from South America had a wingspan of 25 feet and may have weighed 250 pounds.  The modern Andean condor can reach a 10 foot wingspan and weight of 25 pounds (Weidensaul, 1996). The large teratorns went extinct along with the large mammals that they preyed upon about 10,000 years ago ( Houston, 2001).

TURKEY VULTURE

     Although turkey vultures primarily feed on carrion,  they can make their own kills of small animals on rare occasions.  Because of the messiness of their diet, they possess a naked head to prevent the fouling of head feathers.  Vultures are more tolerant of pathogens than other birds, allowing them to feed on carrion.  Their wingspan can reach 6 feet in length.  They can warm themselves in the mornings by partially spreading their wings.  Turkey vulture clutches typically contain 2 eggs. Turkey vultures and the 2 species of yellow headed vultures are among the few birds which possess a developed sense of smell. Black vultures cannot smell and therefore have difficulty hunting in dense forests (unless they follow turkey vultures to carrion, which they are known to do) ( Houston, 2001).

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