BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Gymnogyps californianus | California Condor 



TIMING OF MAJOR LIFE HISTORY EVENTS : 
Age at sexual maturity - California condors do not breed until they are
at least 6 years old and often not until they are 8 years old [27].

Breeding season - California condor pairs begin mating and selecting
nesting sites in December, although many pairs wait until late spring
[13,27].  The egg is laid between January and early April and is
incubated by both parents [27].  The time required to complete a single
nesting cycle may be more than 12 months, so some pairs nest every other
year [19,27].  This pattern varies, however, depending on the abundance
of food and the time of year that the nestling fledges [13].

Clutch size and incubation - California condors lay only one egg [27].
The egg is incubated for 56 to 58 days [13,19,27].  California condor
will sometimes lay a second egg to replace an egg that is lost or broken
[13,27].

Fledging - California condors fledge at about 5 or 6 months of age but
do not become fully independent until they are at least 1 year old.  The
parents sometimes continue to feed the chick even after it has begun its
own flights to foraging areas [13].

Longevity - The average life span of California condors is 15.5 years
[30].  However, they may live to be 30 to 45 years old [27].  A captive
California condor at the National Zoological Park in Washington D. C.
lived for 45 years [14].


PREFERRED HABITAT : 
California condors inhabit rugged canyons, gorges, and forested
mountains mainly between 985 and 8,860 feet (300-2,700 m) and nest
primarily between 2,000 and 4,500 feet (610-1,372 m) [3].

Nesting habitat - Nesting sites are characterized by extremely steep,
rugged terrain, with dense brush surrounding high sandstone cliffs [34].
Nests are often located in caves, crevices, potholes, and on ledges
located on rock escarpments.  Occasionally, they occur in natural
cavities in the upper portions of large, living giant sequoia [13,19].
Contrary to previous assumptions, Snyder and others [25] found that
California condors modify their nest site by constructing substrates of
coarse gravel on which to rest the egg.

The main physical requirements for a condor nesting site are:  location
in sheltered site, suitable roosting perches nearby, fairly easy
approach from the air, space enough to hold two full-grown California
condors, level area where walls are about 2 feet (0.6 m) apart, and
perches nearby for the young bird when it leaves the nest [10].  Most
nest caves face either northeast or southwest [30].  California condors
do not defend a large nesting territory.  Active nests have been located
within 1 mile (1.6 km) of one another [34].

California condor pairs generally change nest sites in successive
reproductive attempts.  Nevertheless, the majority of nest sites have
been used repeatedly, and California condors rarely appear to pioneer
use of new sites [25].

Roosting areas - California condors require roost sites throughout their
range for resting and for protection during periods of inclement weather
[14].  They often have traditional roosting sites located near important
foraging grounds and breeding areas [27].  Roosts located in breeding
areas are often on cliffs or trees, especially snags or bigcone
Douglas-fir.  Roosts in the vicinity of foraging areas are usually found
on tall, open-branched trees rather than on cliffs [20].  California
condors commonly perch until mid-morning and return to the roost site in
the late afternoon after foraging [13].  However, it is not uncommon for
a California condor to stay perched throughout the day [27].

Foraging habitat - California condors require fairly open terrain for
foraging because they need a long runway for easy takeoff and approach
and so they can locate prey [27].  Atmospheric conditions suitable for
soaring generally limit California condor foraging activity to warmer
periods of the day [30].  Most foraging habitat is at lower elevations
than breeding habitat, although there is considerable overlap.  Although
most known breeding sites are 20 miles (30 km) or more from principal
foraging grounds, the birds cover such distances quickly [20].  Flights
between foraging and breeding areas characteristically follow major
ridgelines or proceed from one mountaintop to another.  California
condors formerly foraged along coastal shorelines and rivers, apparently
using more varied habitats than they do presently.  Current foraging
areas are almost entirely on private land used principally for ranching
[19].

Water requirements - California condors regularly drink from and bathe
in freshwater pools.  Suitable pools must provide easy access and
takeoff, and be situated within a convenient distance of foraging areas
[10].

Winter habitat - Winter habitat for California condors is the same as
the habitat used throughout the rest of the year [20].


COVER REQUIREMENTS : 
California condor nest sites are located in areas that provide
protection from storms, wind, and direct sun [34].  California condors
prefer to forage on ridges and in open areas with short vegetation so
they can easily locate prey and to ensure easy takeoff and approach
[13,30].  Carcasses under brush are hard for California condors to see.
They apparently cannot locate food by odor [27].


FOOD HABITS : 
California condors do not kill their own prey.  They feed on the
carcasses of a variety of animals.  Ninety-five percent of their food is
derived from domestic cattle, sheep, horses, and from ground squirrels
(Spermophilus spp.) and mule deer (Odocoileus hemionus).  They show a
preference for deer and calves [10].  They also eat a variety of small
mammals including jackrabbits (Lepus spp.) and cottontails (Sylvilagus
spp.)  [20].  Small mammal bones are an important source of calcium for
California condors.  Normally, the calcium necessary for egg production
comes from the bones of small animal carcasses [36].

Domestic cattle carcasses are a primary food source for California
condors and have become increasingly important as other prey species
have declined throughout the California condor's range [13,27,22].  In
the absence of supplemental feeding, changes in ranch management
practices which reduce or eliminate carcasses on open rangeland may
reduce the survival of the released California condor population [22].


PREDATORS : 
California condors have no known natural enemies besides humans [27].
However, potential predators include black bears (Ursus americanus),
coyotes (Canis latrans), and ravens (Corvus spp.) [25].


MANAGEMENT CONSIDERATIONS : 
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].


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Gymnogyps californianus | California Condor