California condor
| California Condor | |
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| Genus: | (Lesson, 1842)
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| Species: | G. californianus
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| Gymnogyps californianus Shaw, 1797
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The California Condor, Gymnogyps californianus, is a species of bird in one of the vulture families. It is the largest land bird found in North America.
This condor nowadays only inhabits the western coastal mountains of the United States. Although it is primarily a scavenger, feeding on carrion, this species belongs to the New World vulture family Cathartidae, related to storks and not closely related to Old World vultures, which are in the family Accipitridae along with hawks, eagles and kites.
Appearance
The female, contrary to the usual rule among true birds of prey, is smaller than the male. Overall length can range from 117 to 135 cm (46 to 53 inches) and the wingspan averages 2.77 m (9.1 feet). The weigh can range from 7 to possibly 14 kg (15.5 to 31 lbs), with estimations of average weigh ranging from 8 to 9 kg (17.6 to 20 lbs). Most measurements are from birds raised in captivity, so distinguishing measurements between wild and captive condors is difficult. California Condors have the biggest wingspan of any North American bird and are surpassed only by Trumpeter Swan and the introduced Mute Swan in both weight and length (the American White Pelican and Whooping Crane are also longer-bodied). These condors can be mistaken for a small, distant airplane, possibly more often they are mistaken for other species.
The adult california condor is of a uniform black, with the exception of a frill of black feathers nearly surrounding the base of the neck and, especially in the male, large triangular patches or bands of white on the underside of the wings which do not appear until the completion of the first moulting. As an adaptation for hygiene, the head and neck have few feathers (see below photo), exposing the skin to the sterilizing effects of dehydration and ultraviolet light at high altitudes, and are meticulously kept clean by the bird. The skin of the head and neck is capable of flushing noticeably in response to emotional state, which serves to communicate between individuals. This explains why some photos of condors show a bird with nearly white skin and others show glowing reddish-purple skin. The juvenile is mostly mottled dark brown, with blackish coloration on the head, and has gray in place of white on the flight feathers.
The middle toe is greatly elongated, and the hinder one but slightly developed, while the talons of all the toes are comparatively straight and blunt. The feet are thus more adapted to walking as in their relatives the storks, and of little use as weapons or organs of prehension as in birds of prey and Old World vultures.
Behavior
Sexual maturity and breeding behavior do not appear in the condor until 5 or 6 years of age. They may live for 50 years or more, and mate for life. It deposits one or two bluish-white eggs, weighing about 280 grams (10 oz), measure from 90 to 120 mm (3.5 to 4.7 inches) in length and 67 mm (2.6 inches) in breadth, during the months of February and March every second year. The egg hatches after 53–60 days of incubation by both parents. If the chick or egg is lost or removed, another egg is laid to take its place. This is called a double clutch. Researchers and breeders take advantage of this behavior to double the reproductive rate by taking the first egg away for hand-rearing, causing the parents to lay a second egg which they are generally allowed to raise. Brooding of chicks is nearly constant for the first 2 wk after hatching, then shows a rapid decline in the next 2 weeks and ceases during the day at about 1 month of age.
The young are covered with a grayish down until almost as large as their parents. They are able to fly after 5 to 6 months, but continue to roost and hunt with their parents until age 2, when they are displaced by a new clutch. There is a well developed social structure within large groups of condors, with competition to determine a 'pecking order' by body language, competitive play behavior, and a wide variety of vocalizations, even though the condor has no voice box. Adult condors will usually successfully defend their nests and offspring from predators such as bears, Common Ravens and Golden Eagles (adults have no known predators apart from humans).
On wing the movements of the condor, as it wheels in majestic circles, are remarkably graceful. The lack of a large sternum to anchor correspondingly large flight muscles identifies them physiologically as primarily soarers. The birds flap their wings on rising from the ground, but after attaining a moderate elevation they seem to sail on the air. Charles Darwin commented on having watched them for half an hour without once observing a flap of their wings{[citation needed]. They prefer to roost on high places from where they can launch without major wing-flapping effort. Often, these birds are seen soaring near rock cliffs, using the heat thermals to aid them with rising in the air.
Wild condors inhabit large territories, often traveling 250 km (150 miles a day) in search of carrion. In the early days of it's existence as a species, it is thought that the California Condor lived on the carcasses of the "megafauna", which are now extinct in North America. They still prefer large, terrestrial mammalian carcasses such as deer, goats, sheep, donkey, horse, pigs, Mountain Lions, bears or cattle which they spot by looking for other scavengers, who cannot rip through the tougher hides of these larger animals with the efficiency of the larger condor. Alternatively, they may eat smaller mammals, such as rabbits or coyotes; aquatic mammals, such as whales and sea lions; or salmon. Birds and reptile carcasses are rarely eaten. They can usually intimidate other scavengers, with the exception of bears, which will ignore them at a carcass, and Golden Eagles, which will fight a condor over a kill or a carcass. In the wild they are intermittent eaters, often going for a few days without eating, then gorging themselves on several pounds at once, sometimes to the point of being unable to lift off the ground.
Status and conservation
At the time of human settlement of the Americas, the California Condor was more widespread; numerous remains of, and cultural artifacts associated with California Condors attest that Native Americans have always held it in high regard (especially after Merriam's Teratorn, apparently the original "thunderbird", had become extinct). However, climate changes associated with the end of the last ice age and the extinction of the Pleistocene megafauna led to a subsequent reduction in range and population. Prehistorically, California Condors are known from Arizona (Miller, 1960), Nevada (Miller, 1931), New Mexico (Wetmore, 1931, 1932), and Texas (Wetmore & Friedmann, 1938); see also below.
The condor's fickle mating habits and resulting low birth rate combined with a late age of sexual maturity make the bird vulnerable to loss of population. In earlier times, cattle drivers observed condors feeding on the dead young of cattle, and assumed that the birds killed the cattle - a fallacy which led to their extinction in some parts of the western United States. This fallacy was so deeply ingrained that the reintroduction of condors to the Grand Canyon was challenged in court by distant cattle ranchers, who had been erroneously taught by their parents that the bird was a predator of calves and lambs. This delayed their introduction pending a court decision favorable to their reintroduction.
The California Condor remains in danger of extinction; by 1982, only 22 individuals were left alive, all in captivity (The 2005 population stands at about 273, including 127 in the wild)[1]. Significant damage to the condor population is attributed to hunting, lead poisoning (from eating animals containing lead shot), DDT poisoning (Kiff et al., 1979), electric power lines and habitat destruction.
Beginning in the 1980s, a captive breeding program was undertaken to try to restore the species. Condors were released in 1991 and 1992 in California, and again in 1996 in Arizona near the Utah border. The condors were also reintroduced into the wild in the Grand Canyon national park. Their numbers are increasing steadily, particularly in the South Rim of the Canyon, where tourists may view these creatures (as they are attracted by the milling crowds of tourists). The Vinny Segretario Vulture Society is helping to ensure the safety of the California Condors.
Unanticipated deaths among these populations occurred due to contact with Golden Eagles, power lines and other factors such as lead poisoning. Since 1994, captive-bred California condors have been trained to avoid power lines and people. Since the implementation of this aversion conditioning program, only two condors have died as a result of contact with power lines. [2] Lead poisoning due to fragmented lead bullets in large game waste is a particularly big problem for condors due to their extremely strong digestive juices (Thacker, 2006); this lead waste is not as much of a problem for other avian scavengers such as the Turkey Vulture and Common Raven. This problem is expected to be addressed by a requirement that hunters use solid copper bullets when hunting in condor ranges.
In 2003 the first bird fledged in the wild since 1981. In March 2006, a pair of California condors were seen nesting in a hollowed out tree in Big Sur, California. This was the first time in more than 100 years in which a pair of California condors had been seen nesting in Northern California. [3][4]
An image of the California Condor, along with John Muir and Half Dome, appears on the California State quarter that was issued in January 2005.
A Condor chick, #412, wobbled on its legs and took flight from its nest for only the second time in more than 14 years. Steve Thompson, from the Fish and Wildlife Service said "This is a significant event. Each time a condor chick fledges in the wild it brings us that much closer to the goal of the recovery of this great bird."
Taxonomy
See Sibley-Ahlquist taxonomy for an alternative classification.
The genus Gymnogyps nowadays has a relict distribution. During the Pleistocene, it was more widespread in the Americas. From fossils, the Floridan Gymnogyps kofordi (Early Pleistocene) and Gymnogyps howardae from the Late Pleistocene of Peru have been described. A condor found on Late Pleistocene deposits on Cuba was initially described as Antillovultur varonai, but has been recognized to also belong into Gymnogyps. It even may be a subspecies of the California Condor.
The California Condor of today has no accepted subspecies anymore; although its range has much contracted during the Holocene, the species always had a small and much interbreeding population. However, there is a Late Pleistocene palaeosubspecies, Gymnogyps californianus amplus, which occurred over much of the bird's historical range - even extending into Florida - and was larger, about equal in weight to the Andean Condor, and had a wider bill (Fisher, 1944). As the climate changed during the last ice age, the entire population became smaller until it had evolved into the Gymnogyps californianus californianus of today (Howard, 1947, 1962; see also Black Vulture).
References
- Template:IUCN2006 Database entry includes justification for why this species is critically endangered.
- Fisher, Harvey L. (1944): The skulls of the Cathartid vultures. Condor 46(6): 272-296. PDF fulltext
- Howard, Hildegarde (1947): A preliminary survey of trends in avian evolution from Pleistocene to recent time. Condor 49(1): 10-13. PDF fulltext
- Howard, Hildegarde (1962): Bird Remains from a Prehistoric Cave Deposit in Grant County, New Mexico. Condor 64(3): 241-242. PDF fulltext
- Kiff, L. F.; Peakall, D. B. & Wilbur, S. R. (1979): Recent Changes in California Condor Eggshells. Condor 81(2): 166-172. PDF fulltext
- Lesson, René-Primevère (1842): [Description of genus Gymnogyps]. L'Echo du monde savant ser. 2 6(44): col. 1037.
- Miller, Loye (1931): The California Condor in Nevada. Condor 33(1): 32. PDF fulltext
- Miller, Loye (1960): Condor Remains from Rampart Cave, Arizona. Condor 62(1): 70 PDF fulltext
- Thacker, Paul D. (2006): Condors are shot full of lead. Environmental Science & Technology 40(19): 5826. HTML fulltext
- Wetmore, Alexander (1931): The California Condor in New Mexico. Condor 33(2): 76-77. PDF fulltext
- Wetmore, Alexander (1932): Additional Records of Birds from Cavern Deposits in New Mexico. Condor 34(3): 141-142. PDF fulltext
- Wetmore, Alexander & Friedmann, Herbert (1938): The California Condor in Texas. Condor 35(1): 37-38 PDF fulltext
External links
- BirdLife Species Factsheet
- 7" x 4.6" 71.8 KB Condor JPEG provided by the U.S. Fish & Wildlife Service
- Ventana Wildlife Society Retrieved 2006-OCT-7
- Peregrine Fund Retrieved 2006-OCT-7
- Video showing the California Condor