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Two-toed Sloths (Choloepus spp.) Fact Sheet: Reproduction & Development

Two-toed Sloths (Choloepus spp.)

Courtship

(Based on observations in managed care)

  • Mating occurs throughout the year, though some observers detect a marked mating season in March and April
  • Females in estrus appear to initiate mating (Meritt 1985)

Reproduction

Reproductive rate

  • Interbirth intervals:
    • C. hoffmanni about 15 months: young independent at 10 months
    • C. didactylus about 16 months; young independent at 12 months
  • Females do not show a decline in fecundity as they age (Nowak 1999)

Gestation and Birth

Gestation

  • Similar in both Choleopus species: 10 months (Taube 1985)
  • Bradypus gestation about 6 months

Birth

  • Litter size: one
  • Weight: 340-400 g (about 12-14 oz)
  • Length: 25.4 cm (10 in)
  • Mother gives birth on ground or in upside down, hanging position; infant grabs onto her fur and makes its way to her chest to nurse
  • Milk is higher in fat (6.9%) and protein (61%) than cow's milk

Life Stages

Infant (< 1 year old)

  • Infant is born alert and strong, eyes open teeth present, claws fully formed. Gripping reflex enables it to climb to mother's abdomen. Nuzzling and suckling by newborn stimulates release of milk — usually within 48 hours
  • Newborn nurses for 15 days for male infant, 27 days for female
  • Play behavior observed at 15-19 days
  • First hangs upside down at 20-25 days, and regularly feeds away from mother at 5 months
  • Young of all species cease nursing at about a month old, but may take leaves even earlier
  • Young are carried on mother's abdomen for six to nine months and feed on leaves they can reach from the position
  • By 6 months, elimination occurs in adult manner
  • May keep a close association for up to two years

Adult

  • Two-toed sloths reach sexual maturity at approximately three years of age (females) and four to five years old (males)
  • External genitalia small and inconspicuous (sexing is difficult)

Longevity

Longevity (Nowak 1999)

  • Two-toed sloths live 10 to 15 years in the wild and over 30 years in zoos.
  • Note: The National Zoo has a 40 year-old Linné's Two-toed Sloth (Stewart 2004)

Mortality and Health

  • Hunted by jungle cats (jaguar, ocelot) and birds of prey (especially Harpy Eagle)
  • Humans hunt them for meat and pelts
  • Deforestation is also a threat

Maternal Care

Young two-toed sloth on mother's shoulder

A young sloth is weaned relatively early, but stays with its mother for a long time.

Image credit: © San Diego Zoo Global. All rights reserved.

Page Citations

Eisenberg and Maliniak (1985)
Meritt (1985)
Nowak (1999)
Taube (2001)

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