California condor
| California condor | ||||||||||
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California condor ( Gymnogyps californianus ) |
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| Systematics | ||||||||||
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| Scientific name of the genus | ||||||||||
| Gymnogyps | ||||||||||
| Lesson , 1842 | ||||||||||
| Scientific name of the species | ||||||||||
| Gymnogyps californianus | ||||||||||
| ( Shaw , 1797) |
The California Condor ( Gymnogyps californianus ) is after the Andenkondor the second largest type from the family of the World vultures (Cathartidae). It is native to the southwest of the United States (especially California and Arizona ), but was historically widespread as far as the southwest of Canada. As a result of active hunting and passive poisoning by pesticides such as DDT , its population decreased dramatically, especially in the first half of the 20th century. From 1987 to 1992 it was considered extinct in the wild.
In 1987, when the last free-flying condor was captured, only 27 individuals were still alive. However, since they also reproduced well in captivity , animals were repeatedly released into the wild from 1992 onwards in the largest conservation breeding program in the United States. They are now found again in the vicinity of the four release sites: in California in Big Sur and in Pinnacles National Park (these two populations have now united), at the Vermilion Cliffs National Monument in northwest Arizona and in northern Baja California . Currently (as of the end of 2018) there are 488 animals, 312 of them in freedom.
features
The California condor can reach a wingspan of 2.49 to 3.00 meters. Its length is a maximum of 109 to 127 centimeters, the length of the short angular tail 33 to 38 centimeters. The weight is 8 to 14 kilograms. Males grow to be around 10% larger than females. Its plumage is blackish, the feathers on top are lined with brown. The feathers of the ruff are dashed gray. The wings of the wing on the upper side have white tips or hems, on the underside of each wing they form a white triangle. The head is bare, only a few black stubble feathers are on the forehead. The head of the adult birds is yellow to red-orange, the beak yellow, the eyes red.
Young birds have a dark head and wear the neck still down . Their beak is black, their eyes gray-brown. The tail is slightly pointed, the light triangle on the underside of the wing even darker. From the age of three to six or seven, the head turns orange, starting with the neck.
Reproduction
The female of the California condor lays only one egg between February and May. Rock caves and large tree hollows serve as nesting sites. A nest is not built. The egg is incubated by the male and female together until the young bird hatches after about 55 to 60 days. The chick wears a down dress, the head initially remains bare and is yellow or pink. The down plumage later turns gray and extends to the head as well. The nestling period is about six months. After this time, the young condors begin their first attempts at flight. You will be looked after by the elderly for months. The plumage of the adult birds do not get the young birds until they are six years old. They are sexually mature at the age of eight . Due to the long period of brood care , condors only nest every two years. California condors can live to be 45 years old.
nutrition
California condors almost invariably feed on the carrion of larger mammals. Large groups of birds gather to feed on a carcass. They can eat 1 to 1.3 kg of meat at one meal and then starve for several days. They move up to 30 km away from their breeding ground in search of food.
Protective measures
Already at the beginning of the 20th century, the strong decline in the California condor population was clearly noticeable. In the 1950s there were only 150 individuals, in 1968 the number of surviving California condors was sixty and in 1978 only thirty individuals. The California Condor Recovery Team was founded as early as 1973, and in 1980 it was able to begin an intensively operated and financially well-funded program to save the California Condor from extinction. At that time, only 22 birds were left in the wild, and another breeding pair was in captivity. The San Diego Zoo Safari Park and the Los Angeles Zoo have played a key role in the conservation program from the start . The Peregrine Fund in Boise, Idaho and the Oregon Zoo were added later.
The first successes were not achieved until 1988, when a chick first hatched into human care. To increase the number of young birds, the first egg was removed from the eyrie, which caused the females to lay another egg. The first egg removed from the nest was hatched in the incubator and raised by animal keepers. In order to prevent the young birds from being imprinted on humans, special hand puppets were developed that looked like condor heads. The young birds were also played the calls of the adult birds while they were being fed. Several optimizations of the rearing methods led to the fact that between 25 and 30 young birds could be reared per year within a short period of time.
As early as 1992, the first California condors were released back into the wild near Big Sur in the Los Padres National Forest . Later release sites were the Vermilion Cliffs National Monument in Arizona, Pinnacles National Park in California and Baja California in Mexico. In 2002, these released birds first brooded in the wild. Since 2006, the two populations of Big Sur and Pinnacles have merged into a larger, central California population by expanding their territories. In 2014, the first successful brood was confirmed in the state of Utah . The parents come from the wilderness in Arizona, the breeding took place in Zion National Park .
A major cause of the near-extinction is the poisoning of birds with metallic lead from hunting ammunition. In particular, shotgun pellets , which they ingest while eating the carcasses of game shot, are the main source of poisoning. As part of an extensive monitoring program accompanying the reintroduction, it was found that the condors are still at risk from lead today and that therefore neither the reintroduced population may be considered stable, nor can further reintroduction in the previous framework without protective measures lead to a stable population. All released birds are caught approximately every two years and their blood tested for lead. Around a fifth of the animals then have to undergo chelation therapy because the limit values have been exceeded.
In the US state of California, the use of lead-containing hunting ammunition has now been banned in the regions where the condors live. The attempt to ban lead shotshells in a larger area, however, met opposition from the US National Rifle Association , since alternatives such as soft iron have disadvantages in some cases and tungsten or copper balls are more expensive. However, the species cannot be protected permanently without further restrictions. As long as only 0.5% of the carcasses serving as food are contaminated with lead ammunition to the extent that is typical today, the reproduction rate of the animals will be too low for the conservation of the species. This can only be achieved through a total ban on lead ammunition and compliance with this regulation.
Fossil record
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In 1911 the paleontologist Loye H. Miller described the fossil "running bones" ( tarsometatarsus ) of a condor under the name Gymnogyps amplus from Pleistocene sediments in a cave in Shasta County in the north of the state of California . While Miller had previously identified condor fossils from the Pleistocene site of La Brea Tar Pits in Los Angeles as the remains of the recent Californian condor, these were subsequently assigned to the species G. amplus . For a long time it was unclear whether G. californianus and the somewhat more robust and larger G. amplus are separate species or not. Thus G. amplus under the name G. californianus amplus classified as "chronological subspecies" of the California condor. A recent comprehensive comparison of the La Brea material with bone material from the recent Californian condor led to the conclusion that the two differ sufficiently to be able to tolerate G. amplus as a separate species.
The distribution area of Gymnogyps amplus / californianus was significantly larger at the end of the Pleistocene than in the 19th century and extended to the entire southern part of North America. For example, individual bones identified as G. amplus / californianus were found in a fossil-ocality radiometrically dated to 11,000 years ago in the west of the US state of New York . Other Pleistocene finds east of the Rocky Mountains come from Texas and Florida .
Both the (sub) recent restriction of the North American condors to the west of the continent as well as the extinction of the robust form ( G. amplus ) will occur with the climate change at the end of the Pleistocene and with the extinction of many species of the Pleistocene megafauna of North America (including mammoths , mastodons , Horses ) brought into causal connection. The results of isotope studies on the bones of large early Holocene condors suggest that the birds specialized in marine mammal carcasses after the disappearance of the megafauna. The period between 9000 and 7000 years ago is assumed for the splitting off of the recent Californian condor ( G. californianus ) from the robust form ( G. amplus ).
literature
- Noel FR Snyder, Helen A. Snyder: Introduction to the California Condor. California Natural History Guides 81st University of California Press, Berkeley (CA) 2005, ISBN 978-0-520-24256-2
Web links
- US Fish and Wildlife Service: California Condor Recovery Program with annual population data
- Gymnogyps californianus onthe IUCN Red List of Threatened Species .
Individual evidence
- ^ US Fish and Wildlife Service: California Condor ( Gymnogyps californianus ). 5-Year Review: Summary and Evaluation. USFWS, Pacific Region, Portland (OR) 2013 ( PDF 2.2 MB), p. 3 f.
- ↑ US Fish and Wildlife Service: California Condor Recovery Program - 2018 Annual Population Status
- ^ California Condor. from the San Diego Zoo website, accessed May 11, 2016.
- ↑ a b c d e Couzens: Rare birds. 2011 (see literature ), p. 17 ff.
- ^ National Park Service: Zion National Park - Biologists Catch First Glimpse of Condor Chick in Utah. Press release from July 15, 2014
- ^ A b Myra E. Finkelstein, Daniel F. Doak, Daniel George, Joe Burnett, Joseph Brandt, Molly Church, Jesse Grantham, Donald R. Smith: Lead poisoning and the deceptive recovery of the critically endangered California condor. In: Proceedings of the National Academy of Sciences of the United States of America. Vol. 109, No. 28, 2012, pp. 11449–11454, doi: 10.1073 / pnas.1203141109
- ^ Loye Holmes Miller: Avifauna of the Pleistocene cave deposits of California. In: University of California Publications Bulletin of the Department of Geology. Vol. 6, No. 16, 1911, pp. 385-400 ( BHL )
- ^ Loye Holmes Miller: The condor-like vultures of Rancho La Brea. In: University of California Publications Bulletin of the Department of Geology. Vol. 6, No. 1, 1910, pp. 1–19 ( BHL )
- ↑ Harvey I. Fisher: The skeletons of recent and fossil Gymnogyps. In: Pacific Science. Vol. 1, No. 4, 1947, pp. 227-236 ( ScholarSpace )
- ^ A b c Valerie J. Syverson, Donald R. Prothero: Evolutionary Patterns in Late Quaternary California Condors. In: Palarch's Journal of Vertebrate Palaeontology. Vol. 7, No. 1, 2010, pp. 1–18 ( PalArch )
- ^ David W. Steadman, Norton G. Miller: California condor associated with spruce-jack pine woodland in the late Pleistocene of New York. In: Quaternary Research. Vol. 28, No. 3, 1987, pp. 415-426, doi: 10.1016 / 0033-5894 (87) 90008-1