Dwarf Caiman (Paleosuchus palpebrosus) Fact Sheet: Reproduction & Development

Breeding

• Sexual maturity
  • Females: about 8 years old (Campos, Sanaiotti, et al. 2012; Campos, Magnusson, et al. 2013)
  • Males: about 6 years old (Campos, Magnusson, et al. 2013)

Nesting

• Timing
  • Dwarf caimans generally nest in the rainy season (Zilca Campos et al. 2015)
    • Peak nesting corresponds with falling water levels in flooded forests or females lay where nests do not flood (Zilca Campos et al. 2015)
  • Duration may vary with location (Zilca Campos et al. 2015)
    • Amazon: September to November
    • Pantanal: November to January
• Nest size (Medem 1958; Medem 1981, as cited by Trutnau and Sommerlad 2006)
  • No in-depth surveys
  • Diameter: 125 to 145 cm (4.10 to 4.76 ft)
  • Above-ground height: approximately 40 to 80 cm (1 to 3 ft)
• Nest materials and structure
  • Mound-type nest (Grigg and Kirshner 2015)
  • Egg chamber at center of nest (Medem 1971; Campos and Sanaiotti 2006)
  • Eggs covered by mud, clay, decomposing leaves, grass, and twigs (Medem 1981, as cited by Trutnau and Sommerlad 2006)
    • Prevents eggs from drying out or being crushed
• Nest location
  • Usually built in shady location

Incubation

• Incubation period
  • About 90 to 95 days (Medem 1971; Stevenson 2019)
• Clutch size
  • 14 eggs, on average (Medem 1981, as cited by Trutnau and Sommerlad 2006; Campos et al. 2015)
    • Range: 6 to 21 eggs
  • Larger females lay larger egg clutches (Campos et al. 2015)
• Egg
  • Size
    • Typically, about 38 mm x 67 mm (1.5 in x 2.6 in) (Davenport 1995; Marzola et al. 2015; Table 3)
  • Weight
    • 53 to 75 g (1.9 to 2.6 oz) (Medem 1981, as cited by Trutnau and Sommerlad 2006; Davenport 1995; Thorbjarnarson 1996; Campos and Sanaiotti 2006)
  • Shell texture
    • Dense irregular bumps and pits (Marzola et al. 2015)
      • Similar to a golf ball’s surface
• Temperature sex determination
  • Relationship not yet determined in this species (Campos et al. 2019)

Hatching

• Size at hatching
  • About 22 to 24 cm (8.7 to 9.4 in) (Medem 1971; Medem 1981, as cited by Trutnau and Sommerlad 2006)
• Weight at hatching
  • About 38 to 43 g (1.3 to 1.5 oz) (Medem 1967; Medem 1981, as cited by Trutnau and Sommerlad 2006)
• Timing of hatching
  • Amazon: begins in September (Z. Campos, personal communication, 2020)
  • Pantanal: November through May (Campos et al. 2015)
• Young call from within eggshell before hatching (Medem 1971)
• Break out of egg head first (Medem 1971)
• Remain in nest for a few days after hatching (Medem 1981, as cited by Trutnau and Sommerlad 2006)
  • Mother thought to help young emerge from nest and move to water (Medem 1958; Trutnau and Sommerlad 2006)

Investment in care

• Female attends nest during incubation (Campos and Sanaiotti 2006)
• Female continues to provide care for up to 21 months after hatching (Campos, Sanaiotti, et al. 2012)
• Mother–offspring association does not extend past offspring’s second year (Campos, Sanaiotti, et al. 2012)
  • Not known if this is due to juvenile dispersal or change in female behavior
• In managed care, parents protective of young (Trutnau and Sommerlad 2006; Stevenson 2019)

Wild populations

• Not reported

Managed care

• Median life expectancy
  • No AZA estimates

Survival rates

• Campos, Sanaiotti, et al. (2015) report nest mortality (open, empty, or egg shells scattered by predators) rates for 2 locations:
  • Amazon: 63%
  • Pantanal: 46%

Predators

• Humans (e.g., Campos and Mourão 2006; Campos 2015)
• Other crocodilians (Medem 1983, as cited by Magnusson 1989)
• Anaconda, Eunectes murinus (Medem 1983, as cited by Magnusson 1989)
• Possibly jaguar, Panthera onca, and other big cats (Magnusson 1989)

Accidental death

• Killed on roads by motor vehicles (Campos, Muniz, et al. 2012; Muniz et al. 2015)

Parasites (non-comprehensive list)

• Ticks (Morais et al. 2010; Kwak et al. 2019)
• Leeches (Magnusson 1985)
• Nematodes (Magnusson 1985)

Dwarf caiman nest, Brazil.

Dwarf caimans construct a mound-type nest.

After laying, the female covers the eggs with mud, clay, decomposing leaves, grass, and twigs.

Image credit: © Zilca Campos. All rights reserved. Used with permission from the artist.