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After reaching sexual maturity, iguanas reproduce annually until death. Green iguanas mature during their second or third year and live to be 10 or 12 years old, while the large land iguana attains adulthood around 10 years, and may live to age 40. Adult males establish mating territories and are selected by females who prefer larger males. Females may court several males before choosing a mate, A chuckwalla (Sauromalus obesus) at the Arizona Sonora Desert Museum, Arizona. This lizard basks in the sun during the day to reach its preferred body temperature of 100°F (38°C). Photograph by Robert J. Huffman. Field Mark Publications. Reproduced by permission.
and one male may be chosen by several females, all of which take up residence in the male's territory.

Several weeks after mating, the female selects a nesting site where she digs a burrow, creates a special chamber, and lays her single clutch of eggs. Seven to 12 weeks after mating, the green iguana lays 20 to 30 eggs, each about 1.5 in (4 cm) long. The banded iguana lays three to six eggs, each about 1 in (3 cm) long, approximately six weeks after mating.

After laying her eggs, the female exits and fills in her burrow, leaving an air pocket in the chamber for the hatchlings, which appear three to four months later at the onset of the rainy season, when food is abundant. The banded iguana is unique in that egg incubation takes an unusually long five to eight months. The young hatch simultaneously and dig to the surface. In most species, only a small percentage of hatchlings reach maturity.

Additional topics

Science EncyclopediaScience & Philosophy: Hydrazones to IncompatibilityIguanas - Classification And Characteristics, Distribution And Diet, Reproduction, Display Patterns As Attractions And Deterrents, Popularity And Extinction