Green Iguana: where and when to see them

The green iguana is a large, mostly plant-eating lizard native to tropical America, including Costa Rica. Its long tail, dorsal spines and hanging throat fan create a striking silhouette in riverside trees. Despite its name, adults may appear greyish, brown or orange rather than bright green. It is strongly associated with warm lowland habitats and frequently uses trees beside water, where foliage provides food, basking sites and escape routes.

Size

1.2–1.8 m total length

Weight

2–5 kg

Lifespan

Not reliably established

Status

Least Concern

Green iguanas regulate body temperature by moving between sun and shade, often basking on exposed branches before feeding. Males use head movements, body posture and an expanded dewlap in territorial and courtship displays. When alarmed, an iguana may climb away, drop toward water or lash with its muscular tail if cornered. Females leave their usual tree cover to excavate nesting burrows, sometimes gathering where suitable sandy soil is limited. Courtship rituals involve head bobbing and dewlap displays from males, sometimes leading to competitive interactions for mating rights. When threatened, they can deliver a painful bite, and their whip-like tail is a powerful defense mechanism capable of breaking human skin.

• The dewlap functions in visual communication as well as contributing to its distinctive outline.
• Much of an adult's total length consists of the tail.
• Breeding males may become strongly orange in some populations.
• Females lay their eggs in excavated underground chambers.

Costa Rican lowland populations can be observed throughout the year. Sunny breaks encourage basking, while heavy rain may reduce visibility. The Pacific dry season often makes coastal travel easier, but Caribbean weather differs and neither pattern defines a nationwide iguana breeding calendar. While iguanas are present year-round, the dry season (December to April) often provides better viewing opportunities due to clearer weather and iguanas basking more prominently. However, nesting activities typically occur during the early part of the wet season, from May to June.

Typical habitat includes lowland forest edges, riparian woodland, mangroves and other warm landscapes with trees near water. Iguanas may also occupy gardens and disturbed areas where vegetation remains. Egg laying requires suitable ground, making riverbanks and sandy clearings important alongside the arboreal habitat adults use. They are semi-arboreal, spending much of their time in trees, but are also adept swimmers, often taking to water to escape predators. Young iguanas typically inhabit lower branches and dense vegetation for cover, while adults prefer higher canopies for basking and foraging.

Adults primarily eat leaves, flowers and fruit, selecting seasonally available vegetation. Their digestive system relies on microbial fermentation to process fibrous food. Although occasional animal consumption is documented, they should be understood as predominantly herbivorous rather than treated as general-purpose scavengers. Juvenile iguanas consume more insects and spiders than adults, gradually transitioning to a largely herbivorous diet as they mature. This dietary shift is crucial for their growth and development, enabling them to process tougher plant matter.

Common name

Green Iguana

Scientific name

Iguana iguana

Animal group

Reptiles

Size

1.2–1.8 m total length

Weight

2–5 kg

Lifespan

Not reliably established

Status

Least Concern

Identification

Compared with Costa Rica's black spiny-tailed iguana, it has a conspicuous large round scale below the ear and a long tail without strongly whorled rings of projecting spines. Beyond the large subtympanic scale, green iguanas in Costa Rica exhibit a prominent dorsal crest of soft spines running from the neck to the tail. Their coloration can vary from bright green to brownish gray, often with banding, depending on age, mood, and local environment.