Cano Negro Wildlife Refuge

Habitat
The Common Basilisk lives along bodies of water in a variety of forests, including lowland dry, moist, and wet forests, and premontane moist and wet forests. Even in highly disturbed agricultural areas, they can survive in gallery forests or secondary growth near streams.

Range
Basilisk species usually live in low elevations, from sea level to 600 m. The species ranges from southwestern Nicaragua to northwestern Colombia on the Pacific side, and from central Panama to northwestern Venezuela on the Atlantic side.

Physical Description
This lizard can be distinguished from similar species within its range by its large size and the high finlike crests down its back. Males also have high crests on the head and tail. Both sexes are brown to olive, and have a white, cream or yellow stripe on the upper lip and a second stripe along either side of its body; these stripes have higher contrast in juveniles and fade as the lizards age.

Biology and Natural History
Nicknamed the “Jesus Christ Lizard,” this extraordinary reptile may run on water when threatened. This spectacle can be readily witnessed; adults often bask in daylight near water when they are not foraging or resting. At night they sleep on perches close to the ground or as high as 20 m.

When startled, the Common Basilisk escapes by speeding to the nearest edge of water—and continues sprinting. The lizard runs on only its hind legs in an erect position, holding its arms to its sides. This basilisk is so adroit on water because its feet are large and equipped with flaps of skin along the toes; when moving quickly, the lizard can cross a surface of water before sinking. On water it runs an average speed of 8.4 kph (or 5.2 mph), which is just a little slower than its speed on land. Younger basilisks can run 10 to 20 meters on water, while adults cross only a few meters before sinking. Adults do not move slowly, but they weigh more and cannot sprint for as long a time. Once a basilisk submerges, it continues swimming until it is sufficiently far from its pursuer—if the predator has followed past the bank! Although this lizard stays close to water to escape terrestrial predators, it swims only when necessary because there are aquatic animals that would be just as happy to eat the basilisk given the chance.

Females lay multiple clutches of 2 to 18 eggs. Larger females lay more eggs in each clutch. The young are left and hatch after 3 months. Only about 60% of hatchlings survive, as they have many predators. Raptors are the main pursuer, and opossums and snakes also prey on sleeping lizards. If it reaches adulthood, a male will live 4 to 6 years, slightly longer than females. An older dominant male will defend females that live within his territory from young competitors.

Diet
This lizard hunts a wide variety of active prey, including insects, scorpions, freshwater shrimp and fish, as well as small individuals of lizards, snakes, mammals and birds. They also forage on flowers, fruits and buds of plants that grow near water. Juveniles mostly eat insects but may also eat fish.

Height/Weight
Hatchlings weigh a mere 2 g and are 37 to 43 mm long. Adult males are generally 130 to 250 mm and weigh 600 g. Females are generally 135 to 194 and weigh half as much as males. The tails of these lizards comprise 70 to 75% of their total length: for example, on an 800 mm (or 31.5 in) long lizard, 600 mm of its length is tail.

Taxonomy
Order: Squamata
Family: Iguanidae

Habitat
This small crocodilian lives in humid tropic lowlands within rivers, streams, canals, marshes, and swamps. It can also live in water near the ocean. The caiman is more common in areas with high rainfall.

Range
This reptilian species can be found from Tehuantepec, Mexico to central Brazil; it has been introduced to southern Florida, Puerto Rico, and Isla de la Juventud off the coast of Cuba.

Physical Description
This species is much smaller than the American Crocodile (Crocodylus acutus), and is not a threat to humans. In addition to size, a distinguishing trait is the bony ridge between and in front of the eyes, resembling spectacles, granting its common name. Also, on the American Crocodile the fourth tooth on either side of the lower jaw conspicuously sticks out when the croc closes its mouth. The caiman’s teeth are concealed. The caiman is generally a light tan to yellow or brown color with vaguely dark crossbands on the body and tail. Younger caiman are lighter and have more distinct crossbands. For its whole life the belly is a cream to white color and the eyes are gold.

Biology and Natural History
This crocodilian keeps to slow water with a muddy floor. During the day it will swim or bask on soft sandbanks or logs. It hunts at night and is easier to find in the dark with a flashlight. It can also be seen more readily in the dry season when receding water levels restrict more individuals to lower areas.

A mother caiman will lay 15 to 40 eggs in a nest of plant materials that is close to water. She tends to the nest for the next 73 to 90 days. Within the egg, the sex of the caiman is controlled by incubation temperature, known as temperature-dependent sex determination. Meanwhile, parents stay near the nest to ward off egg predators (particularly raccoons) with growling, hissing, and lashing at the water with tail and head. When the babies are ready to hatch, they may scream from within their eggs, calling the mother to open the nest and help the hatchlings to water. She will care for and protect them over the next four months, guarding them from large waterbirds. Adults are only vulnerable to anacondas, large wild cats, and humans.

The illegal market for crocodile and caiman skins was active up until the early 1980s. Thousands of caimans were killed for their skin, and babies were sold alive for the pet trade or killed and mounted.

Diet
The Spectacled Caiman forages more or less opportunistically, eating all animals that are in its habitat. Juveniles mostly eat insects and crustaceans, but larger adults consume fish, amphibians, birds, and corpses of birds or mammals that they find.

Height/Weight
Hatchlings are only 20 to 25 cm (8 to 10 in) from snout to vent and weight 35 to 49 g, but adult caimans are generally 1.25 to 2.5 m (4 to 8 ft) long. Females tend to be somewhat smaller than males. Adult males can weigh as much as 65 kg.

Taxonomy
Order: Crocodilia
Family: Crocodylidae

Habitat
This snake is common among lowland habitats including disturbed zones, secondary forest, dry, moist, and wet forest. It may be found in adjacent premontane moist forest.

Range
Clelia clelia lives on the Pacific slope from southern Mexico to Argentina, and on the Atlantic slope from Guatemala to Argentina.

Physical Description
An important snake, the zopilota looks like a different species when it is young. Juveniles have a solid red body and tail with a pale collar beneath the black head. With this brighter coloration some people expect them to be poisonous, so the juvenile has acquired the extra nickname of Vibora de Sangre (“Blood Snake”). These become large, grey to bluish black adults with black eyes, a pale underside, and scattered darker areas where the underside meets the upper coloration.

Biology and Natural History
This strong, large snake is not feared among Costa Ricans—in fact, it is appreciated. The zopilota eats other snakes, including dangerous pit vipers. The potent fer-de-lance (Bothrops asper) is an ordinary food item for the zopilota, who apparently is immune to the venom of other snakes.

Employing an unusual, combined strategy, this animal attacks prey using both venom and constriction. Its grooved fangs are in the back of its mouth and the venom does not act quickly, so the zopilota will hold its prey behind the head and while it injects venom into the neck, also coils its body around the other snake. The prey is immobilized by the venom but actually killed by constriction. The zopilota has probably evolved to use both tactics because other strong, large snakes are difficult to grasp while venom runs its course.

Clelia clelia has venom and behavior not well-suited to posing a threat to humans. This snake tends to calm down while it is held and rarely tries to strike in self-defense. Even if it were aggressive, with rear fangs it would be difficult for the zopilota to inject venom without taking a little time to chew.

This snake is common on the forest floors in Costa Rica and hunts for other snakes during the night. Occasionally it is also active during the day.

Diet
Sometimes breaking pattern to eat lizards or mammals, the zopilota usually eats other snake species. Atropoides, Bothrops, Crotalus, and Porthidium are common victims.

Height/Weight
This large snake can reach a total length of 2.6 m. Females are longer than males.

Taxonomy
Order: Squamata
Family: Colubridae