Asian Elephant (Elephas maximus) Fact Sheet: Reproduction & Development

Finding a mate

• Females in estrus emit infrasonic call to attract males
  • Audible up to 4 km (2.5 mi) away
  • Calls persist for 5 days but may be receptive only one day
  • Also see Vocalizations
• During musth, older males use roving strategy to locate receptive mates (Keerthipriya et al. 2020; LaDue, Schulte, et al. 2022)
  • Males move through large areas, broadcasting their sexual status to potential mates (e.g., Fernando et al. 2008; Keerthipriya et al. 2020)
    • Use a larger home range than during non-breeding period (Fernando et al. 2008)
  • Often consume less food and lose weight (Desai and Johnsingh 1995)

• Females in estrus prefer breeding with males in musth (Chelliah and Sukumar 2015; Keerthipriya et al. 2020; LaDue, Schulte, et al. 2022)
  • Use male scents, behavior, and possibly physical characteristics to assess mate quality (e.g., see Chemical communication)
• Bull males inspect adult females in a herd (Rasmussen and Schulte 1998)
  • Sniff females’ genitals and urine (Eisenberg et al. 1971; Rasmussen et al. 1982; Rasmussen et al. 1993; Rasmussen et al. 2005; Riddle et al. 2006)
    • Evaluate urine by gathering a sample with trunk tip and placing into mouth
    • Jacobson's organ on roof of mouth detects presence of female sex pheromone
  • Female urine contains a sex pheromone that increases before ovulation (Rasmussen et al. 1982; Rasmussen et al. 1997)
    • Elicits or primes male sexual behavior: flehmen response, erections, and mounting behavior (Rasmussen et al. 1982; Rasmussen et al. 1986; Rasmussen and Schulte 1998)
  • Males may also use female’s dung as an indicator of breeding status (Ghosal et al. 2012)
  • Older males more adept at detecting precise ovulatory phase of females, compared to younger males (Rasmussen et al. 2005)
    • Appear to detect by urine and longer-distance odors

Musth (in males)

• Unique sexual state in male elephants (LaDue, Vandercone, et al. 2022b; LaDue, Schulte, et al. 2022)
  • A rut-like phenomenon (Keerthipriya et al. 2020)
  • Occurs periodically, but among different males at different times (unlike mammals that breed seasonally) (Eisenberg et al. 1971)
• Musth cycle now considered a complex and dynamic phenomenon—rather than stereotypical and uniform for the species/population
  • Initiated by higher levels of androgens (sex hormones), such as testosterone (Jainudeen et al. 1972; Vidya and Sukumar 2005a; Brown 2014; Chave et al. 2019)
• Functions and adaptive value (Keerthipriya et al. 2020; LaDue, Vandercone, et al. 2022b; LaDue, Schulte, et al. 2022)
  • Allows males, especially older males, access to females in groups (i.e., signaling to females their readiness to breed)
  • Facilitates female mate choice
  • Reduces dominance-related aggression among adult males (e.g., Chelliah and Sukumar 2013); often eliminates the need for physical combat (helps prevent injury and death)
    • Older males release compounds that elicit submissive behavior in younger males (Rasmussen et al. 2002; Rasmussen et al. 2005)
    • Younger males in musth release honey-like odors that indicate their non-threatening status to older males (Rasmussen et al. 2002)
• Visual and olfactory indicators (Rasmussen and Greenwood 2003; Riddle et al. 2006)
  • Glands on sides of head (temporal glands) secrete a dark, oily liquid (Miall and Greenwood 1878; Eisenberg et al. 1971; Krishnan 1972)
    • Chemical composition changes with age
  • Dribble urine between hind legs
  • Additional sex pheromones present in breath
  • Also see Chemical communication
• Behavioral indicators
  • Male increases movement or “roaming” (Eisenberg et al. 1971; LaDue, Vandercone, et al. 2022b)
  • More frequent displays (e.g., ear flapping) (LaDue, Vandercone, et al. 2022b) and breeding-specific vocalizations; see Communication
  • More prosocial behavior, particularly with females (LaDue, Vandercone, et al. 2022a)
  • May confront, fight, and chase other males or perceived intruders (e.g., Eisenberg et al. 1971)
    • Some researchers/naturalists report that at least some aggressive behavior is typical of musth males (Eisenberg et al. 1971; Jainudeen et al. 1972)
    • However, LaDue, Vandercone, et al. (2022b) did not find increased levels of aggression or vocalization among wild and zoo-housed Asian elephants (may be different than African elephant musth behavior)
• Age of first musth
  • Wild populations (most studies from Sri Lanka and India)
    • Males of wild populations may first enter musth as early as 14–15 years old (Nowak 2018; Keerthipriya et al. 2020)—but more common after 20 (Eisenberg et al. 1971; Keerthipriya et al. 2020; LaDue, Vandercone, et al. 2022a) or even 30 years of age (Keerthipriya et al. 2020; e.g., LaDue, Vandercone, et al. 2022a)
      • Musth intensity and duration generally increase after age 25 (Nowak 2018)
      • Older males likely better able to outcompete rival males
  • Zoo-housed elephants
    • LaDue and colleagues observed musth across all adult age classes and in individuals as young as 11 years old (LaDue, Vandercone, et al. 2022a; LaDue, Vandercone, et al. 2022b)
      • Early onset may be due to a high-quality diet or other social factors (e.g., few/no rival males present)

Courtship behavior and copulation

(e.g., Corse 1799; Eisenberg et al. 1971; Eisenberg and Lockhart 1972; Shoshani and Eisenberg 1982; Rasmussen et al. 2005, and as noted)

• Pre-copulation
  • Pair members wrestle with intertwined trunks and shake heads from side to side
  • May touch partner at various places on body with trunk
  • Male often reaches over female’s shoulder or back with trunk
  • Male may press chin or mouth to female’s back or hind quarters, slowly positioning her ahead of him
• Copulation
  • Male attempts mounting while female stands still, bracing with her forelegs
  • Copulation typically lasts about 30 seconds
  • Mating bouts may repeat over several days (Krishnan 1972)
• Post-copulation
  • Male may guard female(s) of a herd

Elephants in human care

• In Asia, many elephants in temples, circuses, unaccredited zoos, or care for by private owners (Sukumar 2006)
  • Rarely (or never) bred
  • Long-term declines observed in these populations
• Conception in working females
  • Female individuals most often used in timber industry
  • Females conceive more often during their rest (non-working) period (Mumby et al. 2013)
• In tourism “timber camps” (e.g., in India, Myanmar, Laos, Thailand), female elephants allowed to mate with free-ranging males (Sukumar et al. 1997; Thitaram et al. 2010; Thitaram et al. 2010; Baskaran et al. 2011; Maurer et al. 2017; Reichert et al. 2020)

Mating system and mate choice

• Polygynous (Rasmussen and Schulte 1998; Chelliah and Sukumar 2015)
  • Females attract multiple males, and males of sufficient age and social status mate with multiple females
• Males compete for access to females, who have a short conception period

• Older, dominant males guard females (Chelliah and Sukumar 2015)
  • Chase away younger males

• Less known about female mate choice and post-mating mate choice (LaDue, Schulte, et al. 2022)
  • Among wild elephants, female exercises some choice in mates by moving or running away (Krishnan 1972; Chelliah and Sukumar 2015)
    • Successful mating requires female cooperation
• Musth (see below) thought to mainly benefit older males—but may confer advantages to younger non-musth males (e.g., avoid fights with more dominant males, sneak mating attempts) (Rasmussen and Schulte 1998; Chelliah and Sukumar 2015; Keerthipriya et al. 2020)

Sexual maturity

• Females
  • Wide variation across wild populations (Sukumar 2003)
    • Age not fixed; appears to vary with quality of nutrition, social relationships, population density, etc.
  • Sri Lanka (Sukumar 2003; de Silva et al. 2011; de Silva et al. 2013; Nowak 2018)
    • Lowest age at first conception (in wild populations)
    • Likely reach sexual maturity at about 10 to 12 years old, on average
  • Southern India (Sukumar 1989; Sukumar 2003; Nowak 2018)
    • Reach maturity at about 15 years old (or slightly lower)
  • A large study of timber camp females suggests an age of first conception of 18 to 23 years old (Mar 2002)
  • Younger ages may be typical for some populations (Flower 1943; Sukumar 2003; Sukumar 2006; de Silva et al. 2013), especially in human care (Sukumar 2003; Brown 2014)

• Males
  • Bulls commonly reach maturity at about 14 to 15 years old (but some variation) (Eisenberg and Lockhart 1972; Laws et al. 1975; Sukumar 1989; Nowak 2018)
    • May be physiologically mature as early as 9 years old but may not reach sufficient social status to mate until late teens to mid-twenties (i.e., mate access limited by more dominant males)
      • Also see Musth (in males), above

Breeding

• Seasonality
  • Mating and birth can occur any time during year (e.g., Shoshani and Eisenberg 1982; Santiapillai et al. 1984), but birth pulses common in seasonal environments (Wittemyer 2011; Mumby et al. 2013; Hufenus et al. 2018)
    • Peak breeding periods possible during either the wet season (Santiapillai et al. 1984; Katugaha et al. 1999) or dry season (Mumby et al. 2013; de Silva et al. 2013)
    • Birthing synchronicity may help calves survive

• Male reproduction
  • Males can breed at any time, not only when in musth
    • Testosterone increases up to 20 times higher than during non-musth periods
    • Musth periods last about 4 months

• Female reproduction
  • Estrus cycle
    • Lasts about 15 weeks (range: about 13 to 17), on average (Plotka et al. 1988; Rasmussen and Schulte 1998; Sukumar 2003; reviewed by Brown 2014)
      • Can be slightly shorter in human care
  • Conception period
    • About 3 to 7 days (Sukumar 2003)
• Female lifetime reproduction
  • Typically higher investment in breeding earlier in life (Hayward et al. 2014), though fecundity is relatively stable over a female’s lifetime (de Silva et al. 2013)
    • Calf survival remains high (e.g., Hayward et al. 2014)

• Peak fecundity
  • At about 19 years old (Hayward et al. 2014)
• Late reproduction
  • Females can calve past age 50, perhaps up to 60 years of age (though reproductive rates fall sharply) (de Silva et al. 2013; Lahdenperä et al. 2014)
    • May calve at even older ages in human care
  • Post-reproductive period
    • Some females live well beyond their reproductive years, but uncommon (Lahdenperä et al. 2014)

Gestation

• Approximately 20 to 23 months, on average (Corse 1799; Dittrich 1966; Eisenberg 1980; Sukumar 2003; Meyer et al. 2004; Wittemyer 2011; reviewed by Brown 2014)
  • Among the longest gestation of any mammal

• Pregnancy not visually noticeably until end of gestation period (Shoshani and Eisenberg 1982)
  • Mammary glands and nipples more pronounced, and may produce a watery liquid

Birth

• Interbirth interval
  • 4 to 5 years, on average, but variable (Sukumar 2003; Sukumar 2006; Wittemyer 2011)
    • Range: 3 to 6.5 years (Sukumar 1989; de Silva et al. 2013)
    • Shorter interval under favorable conditions (McKay 1973); longer during harsher conditions (Shoshani and Eisenberg 1982)
  • Older females have longer interbirth intervals (Williams et al. 2020)
• Litter size (Krishnan 1972; Nowak 2018)
  • Usually one calf
  • Rarely twins (e.g., Hundley 1927; Pastorini et al. 2020)
• Weight at birth
  • About 110 kg (240 lb), on average (Dittrich 1966; Nowak 2018)
    • Range: 50 to 150 kg, or 110 to 330 lb)
• Height at birth
  • About 90 cm (75 to 100 cm, or 2.5 to 3.3 ft)
• Labor
  • May be short or last several hours (Shoshani and Eisenberg 1982)
  • Female often consumes some or all of the afterbirth

Investment in care

• Females care for young
  • Nurse and protect calves
    • Guard calves using body
    • Calves walk/stand between adults to stay safe (Eisenberg and Lockhart 1972)
  • Guide or restrain calf movements using trunk
• Allomaternal care (“allomothering”)
  • Females in a herd attracted to young calves
  • Calves looked after by their mothers and other adult and subadult females in their herd (Santiapillai et al. 1984) (Gadgil and Nair 1984; Santiapillai et al. 1984; Rapaport and Haight 1987; Berliani et al. 2019)
  • Cooperative care yields a strong survival advantage for calves
  • Helpers also allow mother time to feed and rest
    • Important for milk production
• Care duration
  • Mothers (and other females in a herd) care for young for 10 to 15 years, until calf reaches sexual maturity
    • Calf dependent for a long developmental period
• Also see Life Stages

Nourishment of young

• Nursing
  • Calves consume about 7 to 9 liters of milk per day (Shoshani and Eisenberg 1982)
  • Calf suckles while female stands in a resting posture (e.g., Corse 1799; McKay 1973)
    • Approaches from mother’s (or other nursing female’s) side (McKay 1973; Shoshani and Eisenberg 1982)
    • Suckles with side of mouth, not trunk (Corse 1799; Nowak 2018)
• Milk composition (Shoshani and Eisenberg 1982; Mainka et al. 1994; Dierenfeld et al. 2020)
  • Changes over the course of a calf’s development
  • Higher in fat for younger calves (ages 1 to 3)
  • More milk solids and protein in milk for older calves
    • Milk protein levels higher during wet season, likely due to higher protein amounts found in food plants
  • Both mother (e.g., age, size) and calf traits (e.g., sex) influence milk composition
• Age at weaning (de Silva et al. 2013)
  • Ranges from 18 months to 4 years, or longer
  • Calf may be forced to wean when a younger sibling is born, usually by 4 years old
  • Some calves may nurse for a little longer
    • Mother may nurse 2 calves at the same time
  • Also see Life Stages

Infant (less than 1 year old)

• After birth
  • Calves soon able to stand (Nowak 2018)
  • Follow mothers in their daily routines within a few days (Nowak 2018)
  • Nap often, about every two hours (Dittrich 1966)
• Early growth
  • Develop many motor skills during first 3 to 6 months (Krishnan 1972; Shoshani and Eisenberg 1982)
    • Gradually gain more ability with trunk
• Group care (“allomothering”)
  • See Parental Care
• Play
  • Young elephants often play in groups (Eisenberg and Lockhart 1972)
    • Mothers may feed nearby while calves play
  • Older infants play extensively, sometimes wandering from the group (McKay 1973)

Juvenile

• Growth
  • Rapid growth in first two years of life (Flower 1943)
  • Initial period of rapid growth slows at about 5 years
    • Decline in growth rate is greater for females than males
  • Reach about 70% of adult height by weaning age (Mumby et al. 2015)
• Weaning
  • See Nourishment of young
• Behavioral differences between the sexes begin to appear around time of weaning (Shoshani and Eisenberg 1982)
  • Females
    • More strongly bond with herd members
    • Usually remain with birth family
  • Males
    • Become more independent, leaving herd for longer periods to feed, explore, or play (especially between ages 4 and 8)

Subadult

• Development
  • Male genitalia and female mammae develop
• Males increase ranging
  • Males often seen away from herds (Shoshani and Eisenberg 1982)
    • At independence, may form groups with males of similar age or associate with older bulls (see Male social associations)
• Can be difficult to visually distinguish subadults from juveniles

Adult

• Growth in females
  • Slows at about 10 to 12 years old (McKay 1973; Shoshani and Eisenberg 1982; Nowak 2018)
    • Plateaus between 15 and 30 years
• Growth in males
  • Full height reached by about 20 years old (Mumby et al. 2015)
  • Weight past age 50 (Sukumar et al. 1988; Mumby et al. 2015)
• Also see Sexual maturity

• Long-lived, even among terrestrial mammals (Lahdenperä et al. 2014)
• Human care
  • Median life expectancy
    • 47.5 years (females) (AZA 2024)

Survival rates

• General patterns
  • Overall mortality rates relatively low, especially at larger size (Sukumar 2003)
  • Eisenberg and Lockhart (1972) reported mortality as high between ages 0 and 2, and also higher when males transition to being subadults
• Influence of sex
  • Mortality in bull males much higher than in females, mainly due to poaching (Sukumar 1989)
• Influence of mother’s age
  • In a study of semi-captive timber (working) elephants in Myanmar, lower survival among offspring from old mothers—but offspring had better body condition and higher reproductive success (compared to offspring from younger mothers) (Reichert et al. 2020; Spagopoulou 2020)
    • Trend spanned generations: shorter lifespan observed in grand-calves of older grandmothers

Predation

(Shoshani and Eisenberg 1982; Sukumar 2003)

• Predators of young and juveniles
  • Tigers
• Predators of adults
  • Humans

Other causes of death

(Choudhury 1999; Sukumar 2003)

• Diseases, parasites and other infections (Choudhury 1999; Sukumar 2003)
  • Anthrax
    • Only disease currently known to cause epidemics
    • Often transmitted by domestic animals that graze near forest habitats
  • Pneumonia-like infections also cause significant deaths
  • Other diseases generally not fatal; also see emerging disease reports from AsESG and IUCN/SSC Asian Elephant Specialist Group (2022)
• Injuries from accidents
  • Falling (especially if a calf falls into a hole, ditch, or mud they cannot escape)
• Starvation, malnutrition, or thirst (due to drought)
  • Worn teeth that make it difficult to eat, or may lose teeth in very old age
• Water pollution
• Birth complications or premature birth
• Bulls fighting during musth
• Causes related to human action or activity
  • Intentional: hunting, trapping, shooting, other retribution, or self-protection
    • See Human–elephant conflict
  • Incidental deaths (e.g., electrocution from damaged power lines; Choudhury 1999)

Allen (2006)
Alter (2004)
Langbauer (2000)
Moss (1990)
Shoshani & Eisenberg (1982)
Sukumar (1989, 1994)