Jump to content

California condor

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by Casliber (talk | contribs) at 09:01, 22 August 2007 ( ). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

California Condor
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Aves
Order:
Ciconiiformes
Family:
Cathartidae
Genus:
Gymnogyps

Lesson, 1842
Species:
G. californianus
Binomial name
Gymnogyps californianus
(Shaw, 1797)
Synonyms

Genus-level:

  • Antillovultur Arredondo, 1976
  • Pseudogryphus

Species-level:

For other uses, see condor (disambiguation).

The California Condor, Gymnogyps californianus, is a species of North American bird in the New World vulture family Cathartidae. Currently, this condor inhabits only the western coastal mountains of the United States, Baja California, and the Grand Canyon. It is the only surviving member of the genus Gymnogyps, but fossil members are known.

It is a large, black vulture with patches of white on the underside of the wings and a largely bald head with skin color ranging from nearly white to a glowing red, depending on the bird’s mood. It has the largest wingspan of any bird found in North America and is one of the heaviest. The condor is a scavenger and eats large amounts of carrion. They are one of the world’s longest-living birds, with lifespans of up to fifty years.

Though never great, condor numbers declined in the 1800's due to poaching, lead poisoning, and habitat destruction. Eventually, a conservation plan was put in place that led to the capture of all the remaining wild condors in 1987. These 22 birds were bred at the San Diego Wild Animal Park and the Los Angeles Zoo. Numbers rose through captive breeding and, beginning in 1991, condors have been reintroduced into the wild. The project is the most expensive species conservation project ever undertaken in the United States. The California Condor is currently one of the world's rarest bird species. As of 2005, there were only 273.[1]

The condor is a significant bird to many Californian Native American groups and takes an important role in many of their traditional myths.

Description

Juvenile

The adult California Condor is 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. The juvenile is mostly a mottled dark brown with blackish coloration on the head. It has mottled gray instead of white on the underside of its flight feathers [2].

As an adaptation for hygiene, the condor's head and neck have few feathers, which exposes the skin to the sterilizing effects of dehydration and solar ultraviolet light at high altitudes. The skin of the head and neck is capable of flushing noticeably in response to emotional state, a capability that can serve as communication between individuals.[3] The skin color varies from nearly white to a glowing reddish-purple.

The female, contrary to the usual rule among true birds of prey, is smaller than the male. Overall length can range from 46 to 53 inches (117 to 135 cm) and the wingspan averages around 9.1 feet (2.77 m).[4] Their weight can range from 15.5 to 31 lbs (7 to 14 kg), with estimations of average weight ranging from 17.6 to 20 lbs (8 to 9 kg). Most measurements are from birds raised in captivity, so determining if there are any major differences in measurements between wild and captive condors is difficult.

California Condors have the biggest wingspan of any North American bird and are surpassed only by the Trumpeter Swan and the introduced Mute Swan in both weight and length. The American White Pelican and Whooping Crane also have longer bodies than the condor. These condors can be mistaken for a small, distant airplane, which possibly occurs more often than they are mistaken for other species of bird[5].

On its foot, the middle toe is greatly elongated and the hind one is only slightly developed. The talons of all the toes are straight and blunt, and are thus more adapted to walking than gripping. This is more similar to their supposed relatives the storks[6][7] than to birds of prey and Old World vultures, which use their feet as weapons or organs of prehension.

Distribution and habitat

California Oak savanna on the east flank of Sonoma Mountain.

In relatively modern times, the California Condor used to roam across the American Southwest. However, the last wild bird was taken into captivity for the breeding program in 1987. Recently, captive-bred condors have been released in southern California, Baja California, and at the Grand Canyon. [8]

The condors live in rocky scrubland, coniferous forests, and oak savannas.[9] They are often found near cliffs or large trees, which they use as nesting sites. Individual birds have a huge range and have been known to travel up to 150 miles (250 kilometers) in search of carrion.

Ecology and behavior

Adult in flight

When in flight, the movements of the condor are remarkably graceful. The lack of a large sternum to anchor their correspondingly large flight muscles restricts them to being primarily soarers. The birds flap their wings when taking off from the ground, but after attaining a moderate elevation they largely glide, sometimes going for miles without a single flap of their wings. They have been known to fly up to speeds of 55 mph (88.5 km/h) and as high as 15,000 feet (4572 meters).[10] They prefer to roost on high perches from which they can launch without any major wing-flapping effort. Often, these birds are seen soaring near rock cliffs, using thermals to aid them in keeping aloft.[11]

The California Condor has one of the longer life spans of birds, reaching up to fifty years. If they survive to adulthood, the condor has few natural predators other than humans.[12] Condors also do not have any vocal cords, so their vocal display is limited to grunts and hisses. [13] Condors bathe frequently and can spend hours a day preening.[14] Condors also undergo urohydrosis, or defecate on their legs, to reduce their body temperature.[15]

Diet

Wild condors inhabit large territories, often traveling 150 miles (250 km) a day in search of carrion.[16] In the early days of its existence as a species, it is thought that the California Condor lived off of the carcasses of the "megafauna", which are now extinct in North America. They still prefer to feast on large, terrestrial mammalian carcasses such as deer, goats, sheep, donkey, horse, pigs, mountain lions, bears, or cattle. Alternatively, they may feed on the bodies of smaller mammals, such as rabbits or coyotes, aquatic mammals, such as whales and sea lions, or salmon. Bird and reptile carcasses are rarely eaten. Since they do not have a sense of smell[17], they spot these corpses by looking for other scavengers, like smaller vultures and eagles, who cannot rip through the tougher hides of these larger animals with the efficiency of the larger condor. They can usually intimidate other scavengers away from the carcass, with the exception of bears, which will ignore them, and Golden Eagles, which will fight a condor over a kill or a carcass. In the wild they are intermittent eaters, often going for between a few days to two weeks without eating[18], then gorging themselves on two to three pounds (1-1.5 kilograms) of meat at once, sometimes to the point of being unable to lift themselves off the ground.[19]

Reproduction

File:BirdCalCondor.jpg
Adult

Condors begin to look for a mate when they sexually mature at the age of six.[20] To attract a prospective mate, the male condor performs a display. In the display, the male turns his head red and puffs out his neck feathers. He then spreads his wings and slowly approaches the female. If the female accepts the male, the pair become mates for life. The pair makes a simple nest in caves or on cliff clefts, especially ones with nearby roosting trees and open spaces for landing. A mated female lays one or two bluish-white eggs every other February or March. The eggs weigh about 10 ounces (280 grams) and measure from 3.5 to 4.7 inches (90 to 120 mm) in length and 2.6 inches (67 mm) in width. If the chick or egg is lost or removed, the parents "double clutch", or lay another egg to take the lost one's place. (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 the condors are allowed to raise.)

The eggs hatch after 53 to 60 days of incubation by both parents. Chicks are born with their eyes open and sometimes can take up to a week to hatch from their egg.[21] The young are covered with a grayish down until they are almost as large as their parents. They are able to fly after five to six months, but continue to roost and hunt with their parents until they turn two, at which point 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.

Conservation

File:Condorchick.jpg
Adult's head.

At the time of human settlement of the Americas, the California Condor was widespread across North America. 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,[22] Nevada,[23] New Mexico,[24][25] and Texas[26]

In modern times, a wide variety of causes helped lead to the condor's decline. 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. Significant damage to the condor population is also attributed to poaching, especially for museum specimens,[27] lead poisoning (from eating animals containing lead shot), DDT poisoning,[28] electric power lines, egg collecting, and habitat destruction. During the California Gold Rush, some condors were even kept as pets.[29]

In addition to this, cattle ranchers observed condors feeding on the dead young of their 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 belief was so deeply ingrained that the reintroduction of condors to the Grand Canyon was challenged by distant cattle ranchers, who had been taught by their parents that the bird was a predator of calves and lambs.

As the condor's population continued to decline, discussion began about starting a captive breeding program for the condors. Opponents to this plan argued that the condors had the right to freedom, that capturing all of the condors would change the species' habits forever, and that the cost was too great.[30] However, the project got the approval of the United States Government and the capture of the last wild condors began. The job was completed on Easter Sunday, 1987, when AC-9, the last wild condor, was captured.[31] There were only 22 condors left, all in captivity. The captive breeding program, led by the San Diego Wild Animal Park and Los Angeles Zoo, got off to a slow start due to the condor's mating habits. However, utilizing the bird's ability to double clutch, biologists began removing the first egg from the nest and raising it with puppets, allowing the parents to lay another egg.

As the number of condors grew, attention began to focus on releasing some back into the wild. In 1988, the US Fish and Wildlife Service began a reintroduction experiment involving the release of captive Andean Condors into the wild in California. Only females were released to eliminate the possibility of accidentally introducing a South American species into the United States. The experiment was a success, and all the Andean Condors were recaptured and re-released in South America.[32] Condors were released in 1991 and 1992 in California, and again in 1996 in Arizona near the Grand Canyon.[33] Though the birth rate remains low in the wild, their numbers are increasing steadily through regular releases of captive-reared adolescents.

A Condor flying in the Grand Canyon, Arizona.

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. [34] 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;[35] 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 the condor's range. [36]

In recent times, nesting milestones have been reached by the reintroduced condors. In 2003, the first bird fledged in the wild since 1981. In March 2006, a pair of California Condors attempted to nest in a hollow tree near 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. [37] In early 2007, a California condor laid an egg in Mexico for the first time since at least the 1930s.[38]

The 2005 population was 273, including 127 in the wild,[39] and the rest in the San Diego Wild Animal Park, the Los Angeles Zoo, or the World Center for Birds of Prey in Boise, Idaho.

The California Condor conservation project is also the most expensive species conservation project in United States history, costing over 20 million federal and state dollars since World War II.[40]

Relationship with humans

A Chumash from the 1800s

Throughout its historic range, the California Condor has been a popular subject of mythology and an important symbol to Native Americans. Unusually,[41] this bird takes on different roles in the storytelling of the different tribes.

The Wiyot tribe of California say that the condor recreated mankind after Above Old Man wiped humanity out with a flood.[42] However, other tribes, like California’s Mono, viewed the condor as a destroyer, not a creator. They say that Condor seized humans, cut off their heads, and drained their blood so that it would flood Ground Squirrel’s home. Condor then seized Ground Squirrel after he fled, but Ground Squirrel managed to cut off Condor’s head when Condor paused to take a drink of the blood.[43] According to the Yokut tribe, the condor sometimes ate the moon, causing the lunar cycle, and his wings caused eclipses.[44] The Chumash tribe of Southern California believed that the condor was once a white bird, but it turned black when it flew too close to a fire [45].

Condor bones have been found in Native American graves, as have condor feather headdresses. Cave paintings of condors have also been discovered.[46] Some tribes ritually killed condors to make ceremonial clothing out of their feathers. Shamans then danced while wearing these to reach the upper and lower spiritual worlds. Whenever a shaman died, his clothes were said to be cursed[47], so new clothing had to be made for his successor.

Some scientists, such as Noel Snyder, believe this process of making ceremonial clothing helped contribute to the condor’s decline.[48] If so, this would be the only species that was endangered by the California natives.[49]

Evolutionary history

California Condor on the 2005 California State quarter

The genus Gymnogyps is a prime example of a relict distribution. During the Pleistocene epoch, this genus was widespread across the Americas. From fossils, the Floridan Gymnogyps kofordi from the Early Pleistocene and the Peruvian Gymnogyps howardae from the Late Pleistocene have been described. A condor found in Late Pleistocene deposits on Cuba was initially described as Antillovultur varonai, but has since been recognized as another member of Gymnogyps. It even may have been a subspecies of the California Condor.

Today's California Condor is the sole surviving member of Gymnogyps and has no accepted subspecies; although its range greatly contracted during the Holocene, the species always had a small and inbred 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, having about the same weight as the Andean Condor. This bird also had a wider bill.[50] 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.[51][52]

The Andean Condor of genus Vultur, the California Condor's closest surviving relative, differs from it by having slightly different markings, slightly longer wings, and a tendency to actually kill small animals to eat.[53].

See Sibley-Ahlquist taxonomy for an alternative classification.

References

  1. ^ California Department of Fish and Game, Habitat Conservation Planning Branch (2005). "California Condor Population Size and Distribution" (pdf). Retrieved 2007-08-13.
  2. ^ BirdLife International (2007) Species factsheet: Gymnogyps californianus. Downloaded from http://www.birdlife.org on 17/8/2007
  3. ^ "California Condors Cool Facts" (html). Retrieved 2007-08-14. {{cite web}}: Text "author Ventana Wildlife Society" ignored (help)
  4. ^ BirdLife International (2006). Gymnogyps californianus. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 4 September 2006. Database entry includes justification for why this species is critically endangered.
  5. ^ Nielson 2006, p. 1
  6. ^ Cracraft, J., F. K. Barker, M. Braun, J. Harshman, G. J. Dyke, J. Feinstein, S. Stanley, A. Cibois, P. Schikler, P. Beresford, J. García-Moreno, M. D. Sorenson, T. Yuri, and D. P. Mindell. 2004. Phylogenetic relationships among modern birds (Neornithes): toward an avian tree of life. Pp. 468-489 in Assembling the tree of life (J. Cracraft and M. J. Donoghue, eds.). Oxford University Press, New York. Accessed 2007-04-10.
  7. ^ Gibb, G. C., O. Kardailsky, R. T. Kimball, E. L. Braun, and D. Penny. 2007. Mitochondrial genomes and avian phylogeny: complex characters and resolvability without explosive radiations. Molecular Biology Evolution 24: 269–­280. HTML abstract accessed 2007-04-10.
  8. ^ BirdLife International (2006). Gymnogyps californianus. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 4 September 2006. Database entry includes justification for why this species is critically endangered.
  9. ^ BirdLife International (2006). Gymnogyps californianus. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 4 September 2006. Database entry includes justification for why this species is critically endangered.
  10. ^ "California condor, (Gymnogyps californianus)" (html). Retrieved 2007-08-14. {{cite web}}: Text "author US Fish and Wildlife Service" ignored (help)
  11. ^ Nielsen 2006, p. 79
  12. ^ "San Diego Zoo's Animal Bytes: California Condor" (html). Retrieved 2007-08-14. {{cite web}}: Text "author San Diego Zoo" ignored (help)
  13. ^ "California Condors Cool Facts" (html). Retrieved 2007-08-14. {{cite web}}: Text "author Ventana Wildlife Society" ignored (help)
  14. ^ "California condor, (Gymnogyps californianus)" (html). Retrieved 2007-08-14. {{cite web}}: Text "author US Fish and Wildlife Service" ignored (help)
  15. ^ "California Condors Cool Facts" (html). Retrieved 2007-08-14. {{cite web}}: Text "author Ventana Wildlife Society" ignored (help)
  16. ^ "California Condor Life History" (html). Retrieved 2007-08-14. {{cite web}}: Text "author Ventana Wildlife Society" ignored (help)
  17. ^ Nielsen 2006, p. 58
  18. ^ "California Condor Life History" (html). Retrieved 2007-08-14. {{cite web}}: Text "author Ventana Wildlife Society" ignored (help)
  19. ^ Nielsen 2006, p. 30
  20. ^ "California condor, (Gymnogyps californianus)" (html). Retrieved 2007-08-14. {{cite web}}: Text "author US Fish and Wildlife Service" ignored (help)
  21. ^ "California Condors Cool Facts" (html). Retrieved 2007-08-14. {{cite web}}: Text "author Ventana Wildlife Society" ignored (help)
  22. ^ Miller, Loye (1960): Condor Remains from Rampart Cave, Arizona. Condor 62(1): 70 PDF fulltext
  23. ^ Miller, Loye (1931): The California Condor in Nevada. Condor 33(1): 32. PDF fulltext
  24. ^ Wetmore, Alexander (1931): The California Condor in New Mexico. Condor 33(2): 76-77. PDF fulltext
  25. ^ Wetmore, Alexander (1932): Additional Records of Birds from Cavern Deposits in New Mexico. Condor 34(3): 141-142. PDF fulltext
  26. ^ Wetmore, Alexander & Friedmann, Herbert (1938): The California Condor in Texas. Condor 35(1): 37-38 PDF fulltext
  27. ^ Nielsen 2006, p. 83
  28. ^ Kiff, L. F.; Peakall, D. B. & Wilbur, S. R. (1979): Recent Changes in California Condor Eggshells. Condor 81(2): 166-172. PDF fulltext
  29. ^ Nielsen 2006, p. 88
  30. ^ Nielson 2006, p. 13
  31. ^ Nielsen 2006, p. 24
  32. ^ "California condor, (Gymnogyps californianus)" (html). Retrieved 2007-08-14. {{cite web}}: Text "author US Fish and Wildlife Service" ignored (help)
  33. ^ BirdLife International (2006). Gymnogyps californianus. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 4 September 2006. Database entry includes justification for why this species is critically endangered.
  34. ^ "California Condors Timeline" (html). Retrieved 2007-08-14. {{cite web}}: Text "author Los Angeles Zoo" ignored (help)
  35. ^ Thacker, Paul D. (2006): Condors are shot full of lead. Environmental Science & Technology 40(19): 5826. HTML fulltext
  36. ^ "Lead bullet ban to aid Condor recovery" (html). Retrieved 2007-08-14. {{cite web}}: Text "author BirdLife International" ignored (help)
  37. ^ "Fresh Hope For Condors" (html). Retrieved 2007-08-14. {{cite web}}: Text "author Sky News" ignored (help)
  38. ^ "California Condor lays egg in Mexico" (html). Retrieved 2007-08-14. {{cite web}}: Text "author Thomas Watkins" ignored (help)
  39. ^ California Department of Fish and Game, Habitat Conservation Planning Branch (2005). "California Condor Population Size and Distribution" (pdf). Retrieved 2007-08-13.
  40. ^ Nielson 2006, p. 7
  41. ^ Nielson 2006, p. 39
  42. ^ Nielsen 2006, p. 37
  43. ^ Nielsen 2006, p. 38
  44. ^ Nielsen 2006, p. 40
  45. ^ Nielsen 2006, p. 40
  46. ^ Nielsen 2006, p. 36
  47. ^ Nielsen 2006, p. 41
  48. ^ Nielsen 2006, p. 41
  49. ^ Nielsen 2006, p. 41
  50. ^ Fisher, Harvey L. (1944): The skulls of the Cathartid vultures. Condor 46(6): 272-296. PDF fulltext
  51. ^ Howard, Hildegarde (1947): A preliminary survey of trends in avian evolution from Pleistocene to recent time. Condor 49(1): 10-13. PDF fulltext
  52. ^ Howard, Hildegarde (1962): Bird Remains from a Prehistoric Cave Deposit in Grant County, New Mexico. Condor 64(3): 241-242.
  53. ^ Nielsen 2006, p. 27

Cited texts

  • Template:IUCN2006 Database entry includes justification for why this species is critically endangered.
  • Lesson, René-Primevère (1842): [Description of genus Gymnogyps]. L'Echo du monde savant ser. 2 6(44): col. 1037.
  • Nielsen, John. Condor: To the Brink and Back- The Life and Times of One Giant Bird. New York: Harper Perennial, 2006.
Wikimedia Commons has media related to Gymnogyps californianus.
Retrieved from "https://en.wikipedia.org/w/index.php?title=California_condor&oldid=152881631"