More info for the term: restoration
California condor populations have declined sharply since the early
1900's. The estimated population between 1966 and 1971 was 50 to 60
birds. The population dropped to nine after some six to eight birds
died during the winter of 1984-1985, including members of four of the
remaining breeding pairs. As a result of this loss the United States
Fish and Wildlife Service, the State of California Department of Fish
and Game, the Los Angeles Zoo, and the Zoological Society of San Diego
agreed that the remaining population should be placed in captivity until
better protection could be afforded to wild birds. The last wild
California condor was captured on April 19, 1987 [26].
Many factors have contributed to the decline in California condor
numbers since the turn of the century. These include: (1) direct
mortality through shooting, capture, egg collecting, and poisoning; (2)
impairment of reproduction through pesticides, disturbance, and food
scarcity; and (3) declining habitat caused by urbanization, agricultural
development, changed ranching practices, and fire control [16].
Contaminants such as lead, organochlorides, organophosphates,
predacides, and rodenticides present a continual hazard to California
condor populations [21,22]. 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
[13].
California condor reaction to human disturbance varies with the duration
and intensity of the disturbance and whether condors are nesting,
roosting, or foraging [27]. Human disturbance normally will not cause
California condors to abandon their nests, but it may discourage them
from nesting in otherwise suitable habitat and may cause nest failure
due to frequent long absences. Nests are often found closer to lightly
used roads and intermittently used foot trails than to regularly
travelled routes or oil well operations [27]. Roosting California
condors are readily disturbed by either noise or movement. Disturbance
late in the day may prevent roosting in that area that night.
Occasional major disturbances do not cause California condors to abandon
regularly used roosts, and they may adapt to general low-level
disturbances. California condors usually feed in relatively isolated
areas and usually leave if approached within 1,000 feet (300 m). They
seldom feed on animals killed on highways or in areas of regular
disturbance [34].
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 [22].
The future of the California condor now depends on the success of the
captive breeding program and reintroduction of birds into the wild
[22,32]. The current recovery plan calls for the reestablishment of two
geographically distinct, self-sustaining wild populations, each
numbering 100 individuals [26,27]. As of summer, 1994, there were four
1-year-old captive-bred California condors living in the wild in the Los
Padres National Forest [37].
Possible future release sites include northern California, the Grand
Canyon, and Baja California [2,23]. According to Rea [23] the most
promising area for restoration of captive-bred California condors
appears to be the Grand Canyon. This prime habitat contains extensive
rugged terrain with open areas and strong updrafts. The inner gorge of
the canyon has relatively limited human disturbance [23].