Spiny Green Lizard

Habitat

Commonly found in open patches of sunlight on trees, rocky outcroppings, pastures, fences, logs, tile roofs, or gardens. Premontane, montane, and even subalpine regions are home to this lizard. They can be found at the top of Costa Rica’s highest mountain, Chirripó. Human-dominated and even urban areas are not foreign territory to the species.

Range
From Guatemala’s mountains, through Costa Rica, and down to western Panama, the Spiny Green Lizard lives from 600-3,800 m in elevation. There are two similar species of lizard in Costa Rica, but S. malachiticus is larger, a darker green, and can survive above 600 m.

National Parks
Chirripó, National Park, Monteverde Cloud Forest Reserve, Santa Elena Cloud Forest Reserve, Children’s Eternal Rainforest, Rincón de la Vieja National Park, Arenal National Park, Juan Castro Blanco National Park, Braulio Carrillo National Park, Volcan Irazu National Park.

Physical Description
The Green Spiny Lizard somewhat describes itself. The small reptile’s stocky body is armored in small spiny scales, but the blunt-nosed head has smooth scales. The lizard is a mostly solid metallic color, but this varies per individual and changes throughout the day, helping adjust body temperature. An individual may tend to be a bright green, bluish green, yellowish green, or as dark as slate or black. Most can become this darker color as they try to absorb more sunlight. Males may have a black stripe around the neck and a bright blue tail; females may also have blue markings. At lower elevations, the Spiny Green Lizards tend toward the brighter greens; at higher elevations, the same species is more dully colored. In both situations they tend to be darker in the morning and become brighter as the sun climbs towards its peak.

Biology and Natural History
Much of this heliothermic lizard’s day is structured around adjusting and maintaining body temperature. To raise body temperature, this animal basks in the sun, so it is commonly visible where it lives. At lower elevations it is found more on trees, roofs, fences, and high perches. At higher elevations it is more terrestrial, clinging to dry, warm spots on rocks or logs. The Spiny Lizard flattens and spreads out its body to absorb more sunlight; when it is warm enough, it will hunt or retreat to shadier spots. This is related to the color variation with elevation—lizards at cool, higher elevations can speed up their heat absorption with darker body colors.

This reptile is little but territorial and males will keep their home ranges far apart, although they may overlap with multiple female ranges. While perching to bask or protect its territory, S. malachiticus will also scan for small prey and run after it. When threatened by a predator, such as a bird, snake, or small mammal, this species will quickly abandon its perch and rapidly retreat to safety.

The female will incubate her eggs within her body and give birth to live young in litters of about six. This lizard often can survive in cold climates, but eggs are sensitive to temperature change. The female protects them from this vulnerability.

Diet
The food for this lizard mostly consists of arthropods, particularly insects.

Height/Weight
Males are generally within the range of 67-98 mm in snout-vent length; females are slightly shorter, at 64-94 mm. The tail will approximately double the total length of the lizard—including it, the animal is about 200 mm long.

Taxonomy
Order: Squamata
Family: Iguanidae

Sources
Leenders, Twan. A Guide to Amphibians and Reptiles of Costa Rica. Zona Tropical, S.A, Miami, FL, 2001.

Robinson, D. C. in: Janzen, Daniel H. Costa Rican Natural History. Chicago: University of Chicago Press, 1983.

Savage, Jay M. The Amphibians and Reptiles of Costa Rica: A Herpetofauna between two Continents, between Two Seas. The University of Chicago Press, Chicago, 2002.

Savage, J. M., N. J. Scott, and D. C. Robinson in: Janzen, Daniel H. Costa Rican Natural History. Chicago: University of Chicago Press, 1983.

-Amy Strieter, Wildlife Writer