Green Basilisk: where and when to see them

The plumed basilisk, also called the green basilisk, is a bright green lizard of humid Central American lowlands. Adult males develop striking crests on the head, back and tail, giving them an unmistakable profile among streamside vegetation. Long toes and a slender body suit life around water and branches. In Costa Rica, the species is especially associated with moist Caribbean lowlands rather than every forest or coastal region.

Size

60–80 cm total length

Weight

Not reliably established

Lifespan

Not reliably established

Status

Least Concern

Plumed basilisks spend much of their time on low branches, roots and vegetation beside freshwater. They bask in sunlight but retreat rapidly when alarmed, sometimes dropping into water. Fast-moving individuals can run briefly across the surface using rapid hind-foot strokes. Males defend areas and signal with head movements and displays of their crests. Females bury eggs in soil, while newly hatched young must find food and evade predators independently. When threatened, their ability to run across water, known as 'Jesus Christ Lizard' behavior, is a spectacular escape mechanism. Males use their head bobbing and crest displays to establish dominance and attract mates. They are generally solitary, only coming together for breeding.

• Adult males have much more elaborate crests than females.
• Expanded hind-toe fringes help support brief runs over water.
• The long tail makes up much of its total length.
• Young hatch fully independent rather than receiving parental feeding.

The species can be active throughout the year in warm, humid lowlands. Less rainy spells may make trails easier to use and basking animals easier to notice. Caribbean Costa Rica has its own rainfall patterns, so the country's Pacific dry-season calendar is not universally applicable. While active year-round, their reproductive activity, which involves nesting, typically peaks during the wet season. During periods of heavy rain, they may seek sheltered perches to avoid being dislodged from vegetation. Cooler temperatures at higher elevations within their range can lead to reduced activity.

Humid lowland forest, wooded stream corridors and lush vegetation around ponds provide typical habitat. Water and nearby cover are important, including in some disturbed landscapes. Caribbean-slope sites in Costa Rica are more appropriate targets than dry Pacific beaches or exposed marine shorelines. They are often found in areas with permanent water sources, such as rivers, streams, and ponds, providing both escape routes and insect prey. Although adapted to humid environments, they can occasionally be found in drier gallery forests along watercourses. They typically remain close to the water's edge, rarely venturing far into open areas.

This basilisk is an opportunistic omnivore. It eats insects and other invertebrates, small vertebrates when available, and some fruit or plant material. Prey may be taken from vegetation or the ground, with food choices changing according to body size and local abundance. Juveniles primarily feed on smaller insects and invertebrates, gradually expanding their diet as they grow larger. Their omnivorous diet allows them to adapt to seasonal changes in prey availability. They have also been observed consuming flowers and other soft plant parts.

Common name

Green Basilisk

Scientific name

Basiliscus plumifrons

Animal group

Reptiles

Size

60–80 cm total length

Weight

Not reliably established

Lifespan

Not reliably established

Status

Least Concern

Identification

Its vivid green coloration and adult male's tall dorsal and tail crests distinguish it from the typically browner common basilisk and striped basilisk. Beyond the green coloration, males possess a prominent casque on their head, further enhancing their distinctive appearance. The females and juveniles have much smaller or absent crests, but still retain the vibrant green hue. Careful observation of crest shape and size can help differentiate sexes and ages.