Giant Panda (Ailuropoda melanoleuca) Fact Sheet: Reproduction & Development

Timing/seasonality

• Breed seasonally (in wild populations) (Schaller et al. 1985; Y. Nie et al. 2012)
• Thought to help both sexes conserve energy demands of an extended breeding period and also cope with limited food resources at start of the mating season (eg, Zhu et al. 2001; Yonggang Nie, Swaisgood, Zhang, Liu, et al. 2012; Pan et al. 2014; Swaisgood et al. 2020)
• Mating season
• February to June (Kleiman 1983; Swaisgood et al. 2020)
• Most activity from March to May, when females reach peak estrus (Reid and Gong 1999; Garshelis 2009b; Y. Nie et al. 2012; Nie, Zhang, et al. 2015)

Mating system

• Polygynous (Reid and Gong 1999; Swaisgood et al. 2016)
• Both sexes mate with multiple partners (about 3 to 5) per season (Garshelis 2009b; Wenshi et al. 2014)
• Mate sequentially, with pairs staying together for days to weeks before mating (Zhu et al. 2001; Schaller et al. 2002; Garshelis 2009b; Swaisgood et al. 2016)
• Mutual mate choice likely important (Martin-Wintle et al. 2015; Martin-Wintle et al. 2017)
• Male–male competition
• Males compete for access to breeding females (Schaller et al. 1985; Nie, Swaisgood, Zhang, Liu, et al. 2012)
• Several males may pursue a female in estrus, with the female usually avoiding them, often climbing and staying in a tree, until ready to mate (Yonggang Nie, Swaisgood, Zhang, Liu, et al. 2012)
• Competition among males initially high but declines after dominance relationships established (Nie et al. 2012a)
• Fight (biting, grabbing, swatting) for about 2 days, then transition to avoidance and threat behavior (giving visual, acoustic signals) that prevent injury (Yonggang Nie, Swaisgood, Zhang, Liu, et al. 2012; Swaisgood et al. 2020)
• Most competitive male (often largest male) guards receptive female and is usually the only male to mate with her (Nie et al. 2012a; Swaisgood et al. 2020)

Courtship behavior and copulation

• Finding potential mates
• Both sexes use scent marking, body posturing, and vocalizations to attract and assess potential mates (Kleiman 1983; Swaisgood et al. 2000; Swaisgood et al. 2002; Charlton et al. 2009; Charlton et al. 2011; Owen et al. 2013; Wei et al. 2015)
• Usually solitary; courtship calls and odors particularly important in synchronizing mating behavior and mate choice (Swaisgood et al. 2000; Swaisgood et al. 2002; Dungl et al. 2008; Charlton et al. 2018)
• Female behavior
• Increased movement in some females, perhaps to eat more food or higher-quality food prior to mating and giving birth (Pan et al. 2014; Connor et al. 2016)
• Females disperse their scent widely and give loud mating calls to attract male suitors (Schaller et al. 1985; Swaisgood, Zhou, et al. 2003; Swaisgood et al. 2004; Nie, Swaisgood, Zhang, Hu, et al. 2012; Owen et al. 2016)
• May use odor to advertise receptivity if other females nearby, instead of vocal cues and visual displays (Owen et al. 2016b)
• May be aggressive toward males during early phases of courtship, interacting more near time of ovulation (Owen et al. 2013)
• Males show steady interest in a female during courtship (Owen et al. 2013)
• When ready to mate, may approach male, walk backward with tail up, and present hindquarters for mounting (Lindburg et al. 2001; Swaisgood, Zhou, et al. 2003; Kersey et al. 2016; Owen et al. 2016; Swaisgood et al. 2020)
• Male behavior
• Scent mark, rub fur (to enhance a distinctive, individual odor), vocalize, and increase their range in search of mates (Schaller et al. 1985: 19; Swaisgood et al. 2000; Hull, Zhang, et al. 2014; Owen et al. 2016; Charlton et al. 2019)
• Display flehmen response and lick female urine to assess if close to estrus (eg, Swaisgood et al. 1999; Swaisgood et al. 2000; Swaisgood et al. 2002; Swaisgood et al. 2004)
• Female hormones (in their urine) may activate seasonal changes in reproductive physiology and sexual behavior of adult male pandas (eg, Wilson et al. 2018; Wilson et al. 2020)
• Females also display flehmen when smelling social odors (Swaisgood et al. 2000)
• Also see Olfactory communication
• Display toward a female (female may also display) and remain near her, just before fertile period (Swaisgood, Zhou, et al. 2003; Owen et al. 2013)
• Multiple males may pursue a female at the same time (Schaller et al. 1985; Zhu et al. 2001; Yonggang Nie, Swaisgood, Zhang, Liu, et al. 2012)
• See Male–male competition, above
• Also see Communication

Breeding

• Sexual maturity
• About 4 to 6 years in managed care, but as late as 7 to 8 years in wild populations (reviewed by Swaisgood et al. 2020)
• Estrus
• Peak receptive period very short, lasting about 1 to 3 days (Kleiman 1983; Swaisgood et al. 2020)
• Full estrus period lasts 10 days, on average (Chorn and Hoffman 1978 citing Peking Zoo 1974a)
• Range: about 1 to 2 weeks (Chorn and Hoffman 1978 citing Peking Zoo 1974a; also see Martin-Wintle et al. 2019)
• Breeding females usually experience a single estrus cycle in spring (Schaller et al. 1985; Lindburg et al. 2001)
• May have a second “weak” estrus cycle in autumn, if a female does not conceive in spring (Chorn and Hoffman 1978; Kleiman 1983; Schaller et al. 1985)
• See Timing/seasonality, above
• Interbirth interval (time between litters)
• About 2 to 3 years, based on a small number of individuals studied (Zhu et al. 2001; Pan et al. 2014; Swaisgood et al. 2020)
• Lifetime reproductive success
• In wild populations, females can give birth to up to 7-or-8 cubs over a span of about 15 reproductive years (Zhu et al. 2001; Swaisgood et al. 2020)
• Can breed to about 20 years in managed care (Swaisgood et al. 2020)

Gestation

• On average, about 140 to 150 days (Chorn and Hoffman 1978 citing Peking Zoo 1974a; Kleiman 1983; Zhu et al. 2001; Pan et al. 2014)
  • Wide range: 84 to 273 days (Song et al. 1994; Zhu et al. 2001; Swaisgood et al. 2020)
    • Most variable of all bears (Swaisgood et al. 2020)
    • Embryo implantation and/or development sometimes delayed (occurs in other mammals, as well) (Garshelis 2009b)
  • Similar duration in managed care (eg, Li et al. 2022)

Birth

• Timing
  • Majority of cubs (75%) born in August or September (eg, Schaller et al. 1985; Pan et al. 2014; Nie, Zhang, et al. 2015; Swaisgood et al. 2020)
• Location
  • Females give birth in sheltered den sites—inside trees with a hollow base or rock caves (eg, Schaller et al. 1985 [see references and photos]; Zhu et al. 2001; Zhang et al. 2007)
  • See Parental Care
• Litter size
  • Usually 1 cub raised by mothers of wild populations—the first born, if healthy (eg, Kleiman 1983; Zhu et al. 2001)
  • Often 2 cubs born but mother very challenged to hold, suckle, and produce milk for more than one cub at a time (Schaller et al. 1985; Zhu et al. 2001; Heiderer et al. 2018)
    • Only bear species that regularly gives birth to more cubs than can be raised (Garshelis 2009b)
      • Benefits/explanation for this reproductive strategy not yet known (Garshelis 2009b)
    • In managed care, animal care specialists help mother care for twin cubs by swapping/rotating them during the day (Zhang et al. 1996; Swaisgood, Ellis, et al. 2003; Heiderer et al. 2018)
• Newborn
  • Weight at birth
    • About 112 g (4 oz), on average, according to Zhu et al. (2001)
      • Range: about 75 to 150 g (2.6 to 5.3 oz) (Zhu et al. 2001)—but wider ranges reported (Garshelis 2009b)
      • Slightly heavier in managed care (Li et al. 2022)
        • About 150 to 160 g, on average (Li et al. 2022)
    • Giant panda newborns particularly small, even compared to other bear species (Ramsay and Dunbrack 1986; Zhu et al. 2001)
      • May weigh 0.1% of mother's weight (Zhu et al. 2001 studying cubs from managed care)
      • 1/3 to 1/4 the size of newborns of other bears (Garshelis 2009b)
  • See “Newborn” in Life Stages for early development

Den habitat and selection

• Mother pandas shelter in tree hollows and rock caves (Chorn and Hoffman 1978 citing Giant Panda Expedition 1974; Sheldon 1975; Zhu et al. 2001; Z. Zhang et al. 2007; Wei et al. 2019)
• Dens only used during early cub development (Swaisgood et al. 2020)
• No long-term or permanent den sites (Chorn and Hoffman 1978; Swaisgood et al. 2020)
• Enclosed den spaces provide more stable environmental conditions (temperature, humidity) for newborns, who cannot yet regulate their body temperature (Zhu et al. 2001)
• Environmental conditions more stable in tree dens than cave dens (Wei et al. 2019)
• Also thought to conceal mother and newborn from predators (Wei et al. 2019; Swaisgood et al. 2020)
• Mothers tend to prefer warm dens, with narrow entrances and deep, roomy interiors close to water (Z. Zhang et al. 2007; Wei et al. 2019; Swaisgood et al. 2020)
• Ability to move freely within den space may reduce risk of mother accidentally injuring cub (Z. Zhang et al. 2007)
• Being located close to water may allow mothers to drink while cubs are still developing (Swaisgood et al. 2016)
• Avoid den sites frequently visited by carnivores, such as Asian bears and yellow-throated martens (Lai et al. 2020)
• May prey on animals that shelter in panda dens, such as rodents, or be predators of or competitors with pandas (Lai et al. 2020)
• Also see Interspecies Interactions

Denning behavior

• Mother stays in den for several days after giving birth (Zhu et al. 2001)
• Does not eat during this time (Zhu et al. 2001; Pan et al. 2014)
• For about the next 2 weeks, mother leaves den only for short periods to drink and eat (eg, Schaller et al. 1985; Zhu et al. 2001)
• During denning period, mother may move cub to several different den sites (Zhu et al. 2001)
• Mother and cub stop using dens after about 4 months (in early winter) (Zhu et al. 2001; Swaisgood et al. 2020)

Mother’s interactions with young

• Mother holds newborn close to her body for about 1 to 2 weeks after birth (Schaller et al. 1985; Zhu et al. 2001; Heiderer et al. 2018; Martin-Wintle et al. 2019)
• Keeps cub warm and prevents hypothermia (eg, Schaller et al. 1985; Zhu et al. 2001; Snyder et al. 2003; Synder et al. 2016; Swaisgood et al. 2020)
• Mother usually keeps newborn in physical contact with her chest, near her nipples for cub to suckle milk (Schaller et al. 1985; G.Q. Zhang et al. 2000)
• Mother sits upright or sometimes rests her head on a hindleg “as a pillow” (Schaller et al. 1985)
• Licks cub for grooming and to stimulate waste elimination (excretion) (Schaller et al. 1985; G.Q. Zhang et al. 2000; Snyder et al. 2003; Snyder et al. 2016)
• Mother consumes cub’s waste, presumably to prevent odors from attracting predators (Schaller et al. 1985)
• Responds to frequent cub vocalizations (eg, Zhang, Swaisgood, et al. 2000)
• Picks cub up in mouth, if walking or moving to a different den site (Schaller et al. 1985; Zhu et al. 2001)
• May use paws to carry older infants but not newborns (Schaller et al. 1985; G.Q. Zhang et al. 2000; Heiderer et al. 2018)
• Also see Newborn

Nourishment of young

• Milk composition
• Initially high in protein, low in carbohydrates and lipids (Griffiths et al. 2015; Nie et al. 2019)
• May boost immunity, improve digestion, and help with rapid growth (Griffiths et al. 2015; Nie et al. 2019)

Newborn (days to 1 month old)

• Giant pandas born as most underdeveloped of all bears—and even all placental mammals (Kleiman 1983; Zhu et al. 2001; Griffiths et al. 2015; F. Wei, Swaisgood, et al. 2015; Swaisgood et al. 2020)
• May reduce physiological demands on mother during pregnancy (Ramsay and Dunbrack 1986; Zhu et al. 2001; Nie, Zhang, et al. 2015)
• Grow rapidly, similar to other bears (Chorn and Hoffman 1978)
• Newborns entirely reliant on mother (Zhu et al. 2001; Snyder et al. 2016)
• Cannot move around independently (Brambell 1976)
• Eyes
• Closed at birth (Brambell 1976; Chorn and Hoffman 1978 citing Peking Zoo 1974a)
• Skin and hair
• At birth, pink skin with short white hairs (Chorn and Hoffman 1978 citing Peking Zoo 1974a; Zhang et al. 1996; Garshelis 2009b; Swaisgood et al. 2020)
• Skin turns gray where fur will be black at about 8 to 10 days old (Zhu et al. 2001)
• Black hairs begin to appear at 1 to 2 weeks (Brambell 1976; Chorn and Hoffman 1978)
• Well-developed coat by 3 weeks (Garshelis 2009b)
• By 30 days, have full adult coloration (Chorn and Hoffman 1978)
• Tail
• Long, relative to body size (Brambell 1976; Schaller et al. 1985)
• Teeth
• None (Chorn and Hoffman 1978 citing Peking Zoo 1974a)
• Behavior
• Nurse for about 30 minutes at a time (G.Q. Zhang et al. 2000)
• Make sharp, high-pitched chirps and “squawks,” which draw mother’s attention and care (Schaller et al. 1985)
• Also see Parental Care

Infant (1 month to 1 year old)

• By 40 to 50 days
• Can raise head and hold it steady (Schaller et al. 1985)
• Attempt crawling (Schaller et al. 1985)
• Around 2 months
• Attempt first steps (Schaller et al. 1985)
• Eyes fully open by 75 days old (Zhu et al. 2001)
• By 3 months
• First able to see at about 90 days of age (Zhu et al. 2001; Pan et al. 2014)
• First (deciduous) teeth begin to erupt (Chorn and Hoffman 1978; Zhang et al. 1996; Edwards et al. 2006b; Pan et al. 2014)
• Vocalize much less (Swaisgood et al. 2003b)
• Better able to independently regulate body temperature, spending little time in physical contact with mother’s body (G.Q. Zhang et al. 2000)
• Hind limbs support full body weight (Chorn and Hoffman 1978 citing Peking Zoo 1974a)
• Able to take more coordinated steps (Schaller et al. 1985)
• 4 to 5 months
• Mother and cub leave den by about 4 months of age (early winter) (Zhu et al. 2001; Swaisgood et al. 2020)
• By 5 months, cub spends time at resting sites (often in trees) while its mother forages (Pan et al. 2014)
• Cub more active—walking and running, rolling, and climbing on mother (Chorn and Hoffman 1978; Schaller et al. 1985)
• Suckles only once or twice per day (Schaller et al. 1985)
• By 6 months
• Cub has canine, incisor, and premolar teeth, and begins to eat bamboo leaves (Schaller et al. 1985; Swaisgood et al. 2020)
• However still dependent on mother’s milk (Chen et al. 2017 citing Zhang and Wei 2006), but bamboo handling at this age usually related to play/learning rather than for gaining energy (Meghan Martin, personal communication, 2025)
• Movements no longer restricted to resting sites (Pan et al. 2014)
• 1 year old
• All permanent teeth have erupted (Zhang et al. 1996)
• Can readily eat bamboo (Schaller et al. 1985)

Juvenile

• Cub weaned at 18 to 24 months (wild populations) (Swaisgood et al. 2020)

Managed care

• Check AZA Species Survival Statistics (if available)

Mortality risk

• Higher mortality reported in winter and early spring, likely due to scarcity of highly nutritious bamboo (Nie, Zhang, et al. 2015; Y. Li et al. 2017; Swaisgood et al. 2020)
• Not likely preyed upon by non-human animals after reaching roughly 50 kg (100 lb), or about 2.5 years of age (Schaller et al. 1985)

Predators

• Little direct evidence; not well known (Hu and Wei 2004)
• Predators of cubs and juveniles
• Leopards (Schaller et al. 1985, Table 6.4)
• Dhole, or Asiatic wild dog (Cuon alpinus) (Schaller et al. 1985; Hu and Wei 2004)
• Newborn pandas possibly preyed on by yellow-throated marten (Martes flavigula), Asiatic golden cat (Catopuma temmincki), or weasels (Schaller et al. 1985; Liu et al. 2023 citing Hu and Wu 2007; Lai et al. 2020)
• Investigation needed
• Human hunting (Chorn and Hoffman 1978; Schaller et al. 1985; Garshelis 2009b)
• Intentional poaching has stopped due to strict government enforcement (Garshelis 2009b)
• Also see Threats to Survival
• Sometimes caught accidentally when hunters target other animals (Garshelis 2009b)

Diseases (non-comprehensive list)

• Most commonly, diseases associated with the gastro-intestinal tract (Qiu and Mainka 1993; Zhao et al. 2023)
• Canine-associated diseases (eg, canine distemper) a concern, especially in managed care (eg, Feng et al. 2016; Zhao et al. 2017)
• Fungal infections also reported (eg, Liu et al. 2013; Tian et al. 2015)
• Also see (Yao et al. 2019) for reintroduction implications and Wang et al. (2018), Table 1

Parasites (non-comprehensive list)

• Worms
• Roundworm Baylisascaris schroederi (McIntosh 1939; Zhang et al. 2008; L. Zhang et al. 2011; L. Zhang et al. 2015; T. Wang et al. 2018; Li, Karim, Li, et al. 2020)
• Only host is the giant panda (Xie et al. 2022)
• Infected pandas have heavy parasite loads (Zhang et al. 2008)
• Causes inflammation of the intestines and other organs, metabolic disorders, and death (eg, Qiu and Mainka 1993; Zhang et al. 2008; L. Zhang et al. 2011, citing Zhang and Wei 2006; T. Wang et al. 2018)
• Causes the most deaths in wild pandas (T. Wang et al. 2018; Swaisgood et al. 2020)
• Other parasitic worms detected (L. Zhang et al. 2011; L. Zhang et al. 2011 citing Hu 2001; Xie et al. 2017; Li, Karim, Li, et al. 2020; Swaisgood et al. 2020;)
• Protozoan infections
• Considered common (Li, Karim, Li, et al. 2020)
• Different kinds can affect muscles, digestive organs, or lungs
• Toxoplasma gondii is the only protozoan known to be potentially fatal in giant pandas (Ma et al. 2015; Swaisgood et al. 2020)
• Ticks, mites, and fleas
• Common and can cause substantial sickness (see Li, Karim, Li, et al. 2020)
• More than a dozen species of ticks reported (Cheng et al. 2013; Li, Karim, Li, et al. 2020; Swaisgood et al. 2020)
• Health effects not well known (Swaisgood et al. 2020)
• Chorioptes panda (Wang et al. 2012)
• Mite species unique to giant pandas
• Causes severe skin itching and hair loss (Li, Karim, Li, et al. 2020)
• Also see review article by Li, Karim, Li, et al. (2020), Table 1; Wang et al. (2018), Table 2

A giant panda mother holds her newborn cub against her body.

Cubs develop slowly. Teeth begin erupting during the third month but nursing continues for 8 or 9 months.

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

Garshelis (2004)
Howard et al. (2006)
Nie et al. (2012)
Owen et al. (2016b)
Pan & Lü (1993)
Reid & Gong (1999)
Schaller et al. (1985)
Snyder et al. (2004)
Swaisgood et al. (2003b)
Zhang et al. (2007b)
Zhu et al. (2001)