Last Updated: Dec 28, 2011
Tours through Costa Rica's lowland rivers and wetlands almost always include a stop to gaze at spectacled caimans – reptiles that could double as floating tree trunks, if not for their unblinking eyes that placidly watch for passing tour boats.
Scientific Name: Caiman crocodilus
Status in the Wild: Common
Habitat: Marshes, Rivers, Swamps
These crocodile relatives are also known as common caimans and they are prevalent throughout Central and South America. Spectacled caimans get their name from a bony protrusion between their eyes that resembles a pair of eyeglasses. Males grow to eight feet in length, while females average under five feet long. Interestingly, common caimans are known to change color, switching between their typical olive-green to almost black during colder months.
On land, spectacled caimans use their legs to lumber across wetlands and riverbanks. They are faster and more agile in the water, where their powerful tails serve as a propeller. Their preferred diet consists of aquatic birds, fish, crustaceans, mollusks and other vertebrates. Larger specimens may even hunt land mammals such as wild pigs. The common caiman is considered to be extremely adaptive, and thrives in almost every habitat within its range.
Spectacled caimans are aquatic, and prefer wetlands, rivers and other bodies of fresh and saltwater up to 1,150 feet above sea level. They range from southern Mexico into northern Brazil. In Costa Rica, they are common throughout the country, except in the high mountain areas near the Central Valley, Cerro de la Muerte, and La Amistad International Park. They are often spotted in Corcovado National Park, Tortuguero, along the Tempisque River, and around Arenal.
Male and female spectacled caimans reach sexual maturity between four and seven years in age. Mating typically occurs toward the end of the dry season, as caimans usually nest during the warmer months of the wet season. However, nesting and hatching in Costa Rica has been observed year-round.
After successful mating, females gather dense vegetation – usually branches, mud and large leaves – to build their nests. Here, they lay clutches of up to 40 eggs. Caiman sex is not determined by genes, but rather by the temperature of the nest – below 87.8º F yields male caimans, and higher temperatures produces females.
Incubation lasts approximately 75 days, at which point the baby caimans emit small sounds to encourage the adults to crack open the eggs and facilitate hatching. For up to four months, the hatchlings will continue to use these vocalizations to call adults back to the nest; scientists believe this to be a type of defense mechanism. Juvenile caimans are born with yellow and black spots that will slowly change to the olive-green typical in adults.
Status in the Wild:
Spectacled caimans are considered a species of least concern. Humans are their most significant predator. Since most of their skin contains osteoderms, a type of scale undesirable in leather goods, this species is not often hunted for its skin.