California Condor (Gymnogyps californianus) Fact Sheet: Reproduction & Development

Coordinated pair flights (Snyder and Snyder 2000; Finkelstein et al. 2015a)

• Earliest act of courtship
• Circle and cruise through nesting territory side-by-side
• Display may advertise occupancy of a territory

Mutual grooming (Finkelstein et al. 2015a)

• Perch side-by-side
• Nibble at each other’s skin and feathers
  • Especially on the head and neck

Wing-out courtship display, while perched (Finkelstein et al. 2015a)

• Most common in late fall, winter, and early spring
• Male displays to female
• Extends wings, droops head, and struts, moving legs up and down
• Circles his mate on the ground or on a boulder
• Air sacs may be inflated
• Display lasts about one minute, on average
  • Copulation often follows this display, but not always
  • Mounting attempts last about one minute
• Occasionally, female performs wing-out display
  • Observed in managed care and reintroduced populations

Mating system

• Generally monogamous (Finkelstein et al. 2015a)
  • Reports of isolated mating trios and extra-pair copulations (Finkelstein et al. 2015a)
• Some pair bonds form during late fall/early winter (Snyder and Snyder 2000)
• Pair members stay together throughout the year (Snyder and Snyder 2000)
• Stable pair bonds over many years; may mate for life (D'Elia and Haig 2013; Finkelstein et al. 2015a)
  • Demonstrated by wild and reintroduced birds
  • If one pair member dies, the other typically adopts a new mate in 1-2 years
    • May move to a different territory

Breeding

• Successfully breed at 6-8 years old (Snyder and Snyder 2005; D'Elia and Haig 2013)
• Clutch size: 1 egg
  • May lay a second “replacement” egg if the first is removed or damaged early in breeding season (Snyder and Hamber 1985)
• Egg laying: January-April (Snyder and Snyder 2000)
• Full nesting cycle takes over a year (Snyder and Snyder 2000; D'Elia and Haig 2013)
  • Adults usually wait for fledglings to become independent before resuming breeding
• At most, raise two chicks in three years (Meretsky et al. 2000)
• Generation length: 20 years (Birdlife International 2015)

Territoriality during breeding

• See Territorial Behavior

Nests

• Female and male spend many hours inspecting nest sites in their territory (Finkelstein et al. 2015a)
  • Move substrate around with bill and feet
  • Chose sites sheltered from weather
• Most nest sites positioned in remote locations (Collins et al. 2000)
• Nest structure is minimal (Finkelstein et al. 2015a)
  • Only use debris from inside cave
    • Gravel, leaves, rat feces, bones, trash, etc.
    • Do not bring in outside materials (unless regurgitated)
  • Only silt or sand if no debris inside cave
  • About 1 m (3 ft) in diameter, though nest boundaries are ill-defined
• Typically, built on floors of small caves on cliff faces or rock ledges (D'Elia and Haig 2013)
  • 600-1,800m (1,970-5,900 ft) above sea level
• Sometimes, in a broken tree top (D'Elia and Haig 2013)
• Pairs usually change nest sites in successive breeding attempts, regardless of breeding success or failure (Snyder et al. 1986; Finkelstein et al. 2015a)
  • May reduce impacts of parasites or predators
  • Average distance between nest sites: 3-4 km (1.9-2.5 mi) apart
    • May be much farther apart
  • Return to nest sites; use multiple times

Egg description

• Pale bluish-green; color fades to white (Campbell 2015; Finkelstein et al. 2015a)
  • No markings
  • Usually a smooth, matte finish
• Oval shape (Finkelstein et al. 2015a)
  • Similar to a chicken’s egg
• Dimensions (including historical specimens) (Finkelstein et al. 2015a)
  • Length: 90-120 mm (3.5-4.7 in)
  • Width: 62-70 mm (2.4-2.8 in)
  • Volumes of first egg laid greater than second or third egg laid (Harvey et al. 2004)
    • No known affect on chick survival
• Mass (including historical specimens) (Finkelstein et al. 2015a)
  • 210-316 g (7.4-11.1 oz)

Chick appearance (Finkelstein et al. 2015a)

• Head and neck
  • Bald
  • Pale yellow-orange; some individuals gray
    • Color turns gray by 18 weeks
• Feathers
  • Downy
  • White
    • Color turns gray within several weeks
• Feet
  • Gray
• Weight at hatching
  • 156-205 g (5.5-7.2 oz) (data from 12 eggs laid in the wild) (Finkelstein et al. 2015)

General

• Both parents intensely care for a single chick (Koford 1953; D'Elia and Haig 2013)
• Substantial attention paid first two weeks after hatching (Finkelstein et al. 2015a)
• Alternate foraging and nest-tending duties (Snyder and Snyder 2000)
• Duties shared more or less equally
• Egg incubation
• After hatching, feeding, brooding, and grooming of chick
• Parents fly up to 180 km (110 miles) away to search for food, but must stay near nest (D'Elia and Haig 2013)
• Complex preening interactions between parents and chick (Snyder and Snyder 2000)
• Intertwine necks, rub heads, nipping
• Hatching: late March-June (Snyder and Snyder 2000; Finkelstein et al. 2015a)
• Nestling period: 5-6 months, on average (Snyder and Snyder 2000)
• Offspring dependent on parents an additional 5-6 months
• Total nestling cycle lasts more than one year (unless chick fledges early)

Incubation and brooding

• Egg incubation period: 53-60 days (Snyder and Snyder 2000)
• Chick brooded almost continuously during first two weeks, then more intermittent (Snyder and Snyder 2000)
• After one month old
• Only brooded at night
• Up to two more weeks
• Left alone during the day so parents can forage
• Parents return regularly to feed chick

Protection of eggs and young

• Parents guard nest intensely, when present (Finkelstein et al. 2015a)
• In late-fledgling period, only near nests 25% of daylight hours
• Chase predators away from nests (Snyder et al. 1986; Finkelstein et al. 2015a)
• Common Ravens prey on eggs
• Golden Eagles prey on fledglings

Nestling and fledgling stages

• Chick in the nest March-June (Finkelstein et al. 2015a)
• Physical description
  • Mostly covered in short, dense, white down (Finkelstein et al. 2015a)
  • Replaced by a wooly, dark gray down within one month
  • Additional short, dense, gray down develops at approximately 50 days old
• Brooding
  • See Parental Care
• Chick solicits food from parents by beating its wings (Snyder and Snyder 2000)
• Explores nest site (as early as 6 weeks old) (Snyder and Snyder 2000; Finkelstein et al. 2015a)
  • May wander outside entrance to nest site, if nest structure permits (i.e., not on top of broken tree)
    • Wander on slopes near nest cave
  • Clumsy, but curious
  • Often fed by parents at nest entrance
    • White band on top of wing may help adults locate chick
• Fledging
  • Nestlings gradually increase independence (Finkelstein et al. 2015a)
    • Walk and explore outside nest cave
    • Exercise wings
    • Make short distance flights (18-275 m; 60-900 ft) when parents away (Snyder and Snyder 2000, 2005)
  • Fly farther as flying skills increase (Finkelstein et al. 2015a)
  • Sometimes fly with parents, although not to foraging grounds (Finkelstein et al. 2015a)
  • Slow to disperse (Snyder and Snyder 2000; Finkelstein et al. 2015a)
    • Remain dependent on parents for about 6 months after fledging
      • Remain in vicinity of nest site for several months (through the summer)
    • May spend more time in natal area (up to another 6 months) if parents do not resume breeding
      • Chased out of natal territory if parents breed again

Immature stage

• Fledglings reach adult weight at about 100-110 days old (Finkelstein et al. 2015a)
  • About two months before fledging
• Join adults and other fledglings at communal roosts and foraging sites (Finkelstein et al. 2015a)
• Many fledglings remain within natal area about 2 years (Finkelstein et al. 2015a)
  • Continue to developing flying skills
  • Progressively increase foraging area
  • Visit many foraging and nesting areas used by a population
    • Gradual learning process
• Depend on parents for an extended period (Snyder and Snyder 2000; D'Elia and Haig 2013)
  • Subordinate to adults at carcasses
    • May not obtain sufficient food

Adults

• Successfully breed at 6-8 years old (Snyder and Snyder 2005; D'Elia and Haig 2013)
• Develop long-term pair bonds with mates, possibly for life (Snyder and Snyder 2000)

(D'Elia and Haig 2013; Finkelstein et al. 2015a)

• Little known
• Thought to be long-lived

Predators

• Adult condors have few predators
  • Mainly humans (Finkelstein et al. 2015a)
  • Infrequently, Golden Eagles (Meretsky et al. 2000)
• Eggs and nestlings (Snyder and Snyder 2000, 2005; Finkelstein et al. 2015a, and as noted)
  • Eaten by Common Ravens, Golden Eagles, and black bears
  • Occasionally, coyotes and mountain lions (Rideout et al. 2012)
  • Historically, grizzly bears

Accidental death (Snyder and Snyder 2000; Rideout et al. 2012, and as noted)

• Lead poisoning
• Electrocution from power lines
  • Birds in managed care trained to avoid power poles (Mee and Snyder 2007)
• Ingestion of trash
  • Glass, plastic, metal
• Collisions with overhead wires
• Drowning
• Eggs/nestlings falling from high or treacherous cave entrances

Survival rates

• Post-fledgling survival high (California, Arizona populations) (Finkelstein et al. 2012)
  • If cases of lead poisoning intensively managed
  • If birds raised in managed care continue to be released

Parasites (non-comprehensive list) (Koford 1953; Finkelstein et al. 2015a)

• Ticks
• Feather lice
• Mexican chicken bugs (Hematosiphon inodora)
• Flies

Diseases (non-comprehensive list)

• West Nile virus (Rideout et al. 2012)
  • Birds released from managed care are vaccinated (Walters et al. 2010; Campbell 2015)

It takes a California Condor chick about 3 days to completely hatch.

Both parents incubate the egg, keeping it warm for nearly two months prior to hatching.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

California Condor chicks hatch with downy feathers, which turn from white to gray within a few weeks.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

A 6-week-old California Condor chick shelters in its nest cave at the San Diego Zoo Safari Park.

California Condors build sparse nests, mainly composed of sand, gravel, and other debris found inside the nest cave. Almost no oustide materials are used in building the nest.

While yet to be studied, it is possible the sand and gravel help to cushion the egg as parents jostle it during incubation.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.