Monito Gecko

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Monito Gecko

Sphaerodactylus micropithecus

ListedOctober 15, 1982
FamilyGekkonidae (Gecko)
DescriptionSmall gray gecko with a contrasting tan or dark brown tail.
HabitatMonito Island; rock crevices.
ThreatsLow numbers, limited distribution, predation.
RangePuerto Rico


The Monito gecko is a small lizard, only about 1.5 in (4 cm) long when fully grown. It is light to dark gray with a spotty patching of brown and tan. Occasionally individuals have white eye-shaped markings on the back. The tan or dark brown tail contrasts sharply with the body. Juveniles are consistently darker than adults are. The tail, which is easily separated from the body, will regenerate. This gecko is similar in appearance and closely related to the Puerto Rican gecko (Sphaerodactylus macrolepis ).


Based on similar species and limited observations, Monito geckos are thought to breed between March and November. This species has not been closely studied, and little is known of diet, behavior, or habitat preference.


Monito Island is an islet situated halfway between Puerto Rico and Hispaniola, 3 mi (5 km) northwest of Mona Island. It consists of a limestone plateau with a total surface area of less than 38 acres (15 hectares), surrounded by nearly vertical cliffs. The highest elevation on the island is 218 ft (66 m). Cliff bases have been eroded and undercut by wave action. Mean annual rainfall is 31 in (79 cm). The vegetation is a dry scrub, consisting mostly of shrubs, dwarfed trees, and cacti. Monito geckos have been observed sunning on rock piles and have scurried away to hide under rocks and plants.


This lizard has been found only on Monito Island. In 1982 personnel from the U. S. Fish and Wildlife Service and the Puerto Rico Department of Natural Resources surveyed the entire island for the Monito gecko and observed 24 individuals. Because of the rugged topography, this count does not reflect the actual number of geckos on the island but is an indication of its relative rarity.


The Monito gecko is an extremely rare lizard with a range restricted by the small size of its island home. Never very numerous, it is further threatened by a large population of introduced black rats that are known to prey on young lizards and lizard eggs. After the Second World War, the island was used by the U.S. Air Force as a bombing range, which caused extensive damage to the habitat. Although the vegetation appears to have recovered somewhat, bomb damage is still very evident over much of the island.

Conservation and Recovery

Monito Island is owned by the Puerto Rican Commonwealth and is currently managed as a reserve for seabirds. To limit human disturbance of the habitat, unauthorized visitation of the island has been prohibited. The most pressing need is for some form of rodent control to diminish the rat infestation. In the absence of rats, it is likely that the gecko population would recover and stabilize. In 1985, this species was listed as Endangered under Puerto Rico's Regulation to Govern the Management of Threatened and Endangered Species. The entire island has been designated as Critical Habitat for the Monito gecko.


U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345

Caribbean Field Office
U.S. Fish and Wildlife Service
P.O. Box 491
Boquerón, Puerto Rico 00622
(809) 851-7297


Dodd, C. K., Jr., and P. R. Ortiz. 1983. "An Endemic Gecko in the Caribbean." Oryx 3 (17): 119-121.

Hammerson, G. A. 1984. "Monito Gecko Survey." Department of Natural Resources, San Juan, Puerto Rico.

Ortiz, P. R. 1982. "Status Survey of the Monito Gecko." Report. Department of Natural Resources, San Juan, Puerto Rico.

Schwartz, A. 1977. "A New Species of Sphaerodactylus from Isla Monito, West Indies." Proceedings of the Biological Society of Washington 4 (90): 985-992.

U.S. Fish and Wildlife Service. 1986. "Monito Gecko Recovery Plan." U.S. Fish and Wildlife Service, Atlanta.