San Francisco State University
Geography 316: Biogeography
In progress 12/10/2001
The Biogeography of California Condor
( Gymnogyps californianus)
by Kaoru Dobeta, student in Geography 316, Fall 2001
|From the Hawk Conservancy||By Clendenen. U.S. Fish and Wildlife Service|
Family : Vertebrate
Species: Gymnogyps californianus
Description of Species:
|The California condor is the largest flying land bird in North America. Adults weigh approximately 10 kilograms (22 pounds) and have a wingspan up to 2.9 meters. Adults have a bare, orange or yellow-orange head and neck, and a white bill. Both sexes of this species have similar coloration (Brown 1997). Its head and neck are bare of hair or feathers, except on the forehead which is covered with stiff, black feathers. There is a prominent ruff of lanceolate feathers around the neck. The condor's back, wings, tail, and under parts are black. The underwing coverts and axillaries are white. Its bill and feet are gray horn colored, with a small patch of red on the knees (Palmer 2001). Immature condors have a dark head and neck that are covered with gray down. The underwing patch may vary from mottled white to nearly all black. The color of the head and neck turns orange and the underwing patches become white (Brown 1997).|
|The size comparison of Condor (Darlington 1987)|
|11,000 years ago, condors were native to several different parts on the continent. Sightings were recorded in upstate New York, Florida, British Columbia, and throughout the Southwest and northern Mexico. Its bones were discovered in Florida early on, and recently its former presence in upper New York state was confirmed by Richard Laub of the Buffalo Museum of Science and David Stedman of the New York State Museum(Darlington 1987). When the '49ers were trekking to California, the condor had retired behind the Rockies, and it survived into the 20th century only in California and Baja California (Darlington 1987). By World War II breeding condors were limited to California's southern Sierra Nevada, the Coast Range behind Santa Barbara, and the east-west ranges (Tehachapi Mountains) that connect the two across the southern end of the San Joaquin Valley. The condor's decline began with the beginning of European colonization (Smith 1978).||
|The map of distribution (Smith 1965)|
Currently the California condor is endangered. Its distribution is limited to Arizona, Southern and Central California (Los Angeles Zoo 2001). The California condor originally inhabited the California mountains and fed in the flat valleys and coastal areas. Condors require large areas of open savannah, grasslands, and large trees for nesting and roosting (Pattee et al. 1990). By 1940 the range had been reduced to the coastal mountains of southern California with nesting occurring primarily in the rugged, chaparral-covered mountains, and foraging in the foothills and grasslands of the San Joaquin Valley.
Today condors are being reintroduced into the mountains of southern California north of the Los Angeles basin, in the Big Sur vicinity of the central California coast, and near the Grand Canyon in Arizona (Meretsky et al. 2000).
Natural History :
Feeding: The California condor is a strict scavenger, it does not kill prey and feeds only on animals that are already dead, which it finds by sight and by following other scavengers. Unlike turkey vultures, condors do not have an exceptional sense of smell. They instead find their food visually, often by investigating the activity of ravens, coyotes, eagles, and other scavengers (Palmer 1988). Without the guidance of their parents, young inexperienced juvenile California condors may also investigate the activity of humans. As young condors learn and mature, this curiosity with humans diminishes (Brown 1997).
Breeding: The California condor breeds every other year, laying one egg each
time (Meretsky et al. 1999). The pairs of California condors stay together over successive
seasons, but if one partner is lost the other will pair with a new mate. Nesting takes
place on inaccessible areas such as cliffs and caves. The California condor does not
construct its own nest (Snyder et al. 1986). Parents take turns incubating the egg that
will hatch after approximately 56 days. The average egg weighs 10 ounces. If the egg is
eaten or broken, parents will produce a new egg in three or four weeks. Sexual maturity is
reached at about six years of age (Meretsky et al. 1999).
Breeding season: California condor pairs begin mating and selecting
|The condor is a member of the family Cathartidae, the New World vultures, a family of seven species, including the closely related Andean condor (Vultur gryphus) and the sympatric turkey vulture (Cathartes aura). Two condors, Gymnogyps and vulture, are closely related to the New World vultures. Vulture begins to breed at 8 years old in captivity and a captive female Gymnogyps laid a fertile egg when 6 years old (Silbley and Ahlquist 1990). According to the branch lengths in the figure, it seems they are the closest among Cathartidae.|
|The cladogram of the family Cathartidae ( Silbley 1990)|
Since humans have been on the earth, condors
have been flying in California. The condors history and humans are closely
linked each other. The fossil record of the
genus Gymnogyps dates back about 100,000 years to the Middle Pleistocene
epoch. The record reveals that the species once ranged over much of the southern United
States. California condors nested in west Texas, Arizona, and New Mexico during the Late
Pleistocene. Many fossils, eggshells, non-fossilized bones, and feathers have been found
in cave with humans relics within the Grand Canyon, indicating that it was an
important historical nesting area (Smith and Easton 1965). The fossilized remains of a closely related
species, the extinct La Brea Condor (Breagyps clarki), has been discovered in the
Rancho La Brea Tar Pits. The extinct La Brea Condor was slightly smaller than the living
but endangered California condor and had a longer, more slender beak (Smith 1978).
In terms of DNA, the California condor is unique (Szabo 1997) because its evolution has over several million years in California where the diversity of climates and landscapes, and all the barriers to migrations such as rivers, mountains, and deserts, has isolated it (Bowman 2001). California is one of the most biologically diverse areas in the world. Within its 160,000 square miles, California harbors more unique plants and animals than any other state (Bowman 2001).
The California condor is one of the world's rarest and most imperiled vertebrates. By 1930, California Condors had been completely killed off in the Southwest. Soon after, the condor began to become rare in California's Central Valley (Darlington 1987). In 1967, the condor was added to the government's list of endangered species. The Endangered Species Act was finally passed in 1973(The Peregrine Fund 2001). By the early 1980's, only nine wild condors remained. Twenty-four additional birds existed in captivity. The threat of losing the condor to extinction forced the government in 1987 to round up the remaining birds in the wild and attempt to reestablish the species through captive breeding. The first successful breeding of the captive birds occurred in 1988. The condor population continued to grow after that, and 103 individuals existed in 1995. Beginning in January 1992, recovery program officials began releasing captive-produced condors back in the wild in the species native range in California. Birds were also released near the Grand Canyon (The Peregrine Fund 2001).
California condor populations have been declining throughout this century. Some researchers have pointed out the reasons that California condor have been endengered.
Contaminants such as these present a continual hazard to California condor populations (Pattee et al. 1990). California condors ingest any poisons present in the carcasses they feed upon. Even if concentrations of poisons are not fatal to adults, they may kill chicks and immature birds (Lowe et al. 1990).
California condor eggs, being large and rare, were once favored by egg collectors. The number of eggs taken by collectors wouldn't seem to be very significant between 1881 and 1910, for example, collectors took about 50 eggs from condor nests but the loss of even a small number of eggs had a definite impact on their populations (Pattee et al. 1990). Condors have a very low reproductive rate they only lay one egg every other year, and don't even begin breeding until they are five to eight years old (Meretsky et al. 1999). Every egg is crucial to the survival of this ancient species, which probably never existed in great numbers.
Habitat loss continues to pose a major long-term problem for California condors. Conversion of rangelands to agriculture, home sites, gas and oil developments, and other urban and industrial uses results in less available suitable habitat (Lowe et al. 1990). The habitat loss diminishes the availability of carrion, their food source. Consequently, its population has declined (Pattee et al. 1990).
population (as 2001, September 1)
Los Angeles Zoo
San Diego Wild Animal Park
World Center for Birds of Prey, Boise, Idaho
TOTAL CAPTIVE POPULATION:
(Source: California Department of Fish and Game)
TOTAL IN THE WILD:
(Source: California Department of Fish and Game)
Brown, N. L. (Jan 14, 1997). California Condor. [Online]. Available: http://arnica.csustan.edu/esrpp/condor.htm/ [7 October, 2001].
Darlington, David. 1987. In Condor Country. Boston. Hungton Mufflin Company.
Los Angels Zoo. (2001,September 1). Condor stats. [Online]. Available: http://www.lazoo.org/cstats.htm [7 October, 2001].
Lowe, D. and Matthews, J. et cl. 1990. The official World Wildlife Fund guide to endangered species of North America. Washington, DC: Beacham Publishing, Inc.
Meretsky, V.,Snyder,N., Beissinger, S., Clendenen, D. and Wiley, J. 2000. Demography of the California condor: Implications for Ressestablishment. Conservation Biology. 14(4): 957-967.
Palmer, Bruce K, Biology of California Condor. Recovery Program Coordinator, Ventura Fish and Wildlife Office. [Online]. Available: http://pacific.fws.gov/condor/facts.htm [7 October, 2001].
Palmer, Ralph S., editor. 1988. Handbook of North American birds. Volume 5. New Haven, CT: Yale University Press.
Pattee, O., Bloom, P., Scott, J. and Smith, M.1990. Lead hazards within the range of the California condor. Condor. 92(4): 931-937.
Ricklefs, R. E. 1978. National Audubon Society, Advisory Panel on the California condor. The california condor. Audubon Conservation Report No. 6. Washington.
Silbley, Charles G. and Ahlquist, Jon E. 1990. Phylogeny and Classification of Birds. Yale University Press. New Haven and London.
Smith, Dick. 1978. Condor Journal The History,
Mythology and Reakity of the California Condor. Santa Barbara, CA. Capra Press.
Smith, Dick. and Easton, Robert. 1965. California condor vanishing American, a study of an ancient and symbolic giant of the sky. McNally and Loftin. Charlotte/ Santa Barbara.
Snyder,N., Ramey,R. and Sibeley, F. 1986. Nest-Site Biology of the California Condor. The Condor. 88(2): 228-242.
Szabo, Nick.1997. Measuring Complexity. [Online]. Available: http://szabo.best.vwh.net/complexity.html [November 1, 2001].
The Hawk Conservancy. [Online] Available: http://www.hawk-conservancy.org/priors/california.htm [October 25 ,2001].
The Peregrine Fund. 2001. California Condor Fact Sheet. [Online]. Available: http://www.peregrinefund.org/condor_factsheet.html
[November 1, 2001]
The U.S. Fish and Wildlife Servive. [Online] Available: http://pacific.fws.gov/condor/ [October 25, 2001]
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