Malpelo Island Xeric Scrub

The Near Threatened Boulenger’s leaf-toed gecko is only found on two islands, including Malpelo, a small, isolated Pacific island. The near vertical rock faces of the island’s perimeter make it difficult for human access, but it is no deterrent to the Boulenger’s leaf-toed gecko’s unique physiological adaptations to climbing. Malpelo Island is nearly uninhabited and seldom visited, thus despite its limited distribution the Boulenger’s leaf-toed gecko does not face any major threats within this ecoregion. However its population remains susceptible to competition or predation by any exotic species being introduced.

Malpelo Island is a small, isolated Pacific island 435 km to the west of Colombia and south of Panama. The main island itself is roughly 8 km² in size, 2.5 km long, and 800 m across at its widest point. It is also surrounded by several smaller rock outcroppings. Climate is oceanic and wet tropical, with high humidity and abundant rainfall. Temperatures average around 28˚C. 

There are no areas of permanent fresh water on the island, although frequent rains accumulate and pass through temporary rock pools, seeps, and springs. The island is of volcanic origin. Geological surveys estimate that it was once 8–10 times larger than its present size—maritime weathering have eroded the island and formed steep cliffs and sea caves along its sides. Very little soil is present due to a lack of parent material, heavy erosion, and steep surfaces. The exception is at higher elevations and where surfaces are flat. 

Vegetation on the island is sparse and concentrated in areas that offer surface soil and protection from high winds and erosion. The predominant vegetation is composed of algae, mosses, and lichens which grow on vertical rock faces. Patches of grass and scrub occur in areas with permanent soil or in restricted areas. A fern species is found in association with these plants. This scant vegetation is the basis for a complex community of animals, including two species of lizard, a land crab, and several invertebrates.

Considering the island’s position and the surrounding water currents, Malpelo represents the convergence of biogeographical elements from the Galápagos, Cocos Islands, mainland Colombia, and even the Indo-Pacific. Though the terrestrial plants and animals of Malpelo Island are not particularly diverse, the island contains important breeding and nesting grounds for many seabirds and supports many vertebrate species found nowhere else in the world. No native mammals or amphibians exist on the island. 

The most abundant bird species is the orange-billed masked booby, and Malpelo Island has the second largest masked booby colony in the world. The only other bird species known to breed on the island is the swallow-tailed gull. Three species of endemic reptile, the Malpelo anole, the dotted galliwasp lizard, and the Malpelo gecko, are also found on the island. These lizards feed on insects and occasionally crabs, and the dotted galliwasp occasionally eats fish dropped by birds and carrion.

The terrestrial species on Malpelo Island remain in relatively good condition; no exotic species have been introduced, no permanent human habitations exist aside from a military garrison, and the island is otherwise unchanged by mankind. Malpelo Island is recognized as a Fauna and Flora Sanctuary (IUCN category IV, gazetted 1995) by Colombian decree. The priority conservation actions for the next decade will be to: 1) conduct research to improve understanding of the ecoregion; 2) monitor the introduction of invasive species; and 3) limit human footprint on the island.

Citations 

1.  Schipper, J. 2018. South America: Island off the coast of Colombia in the Pacific Ocean. https://www.worldwildlife.org/ecoregions/nt1311. Accessed June 14, 2018.
2. Wolda, H. 1975. The ecosystem on Malpelo Island. Pages 22-26 in J. Graham (editor), The Biological Investigation of Malpelo Island, Colombia. Smithsonian Contributions to Zoology, No.176.
3. Birkleland, C., D.L. Meyer, J.P. Stames, and C.L. Buford. 1975. Subtidal Communities of Malpelo Island. Pages 44-46 in J. Graham, editor, The Biological Investigation of Malpelo Island, Colombia. Smithsonian Contributions to Zoology, No. 176.
4. Vasconcelos, R. 2013. Hemidactylus boavistensis. The IUCN Red List of Threatened Species 2013: e.T18486000A18486039. http://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T18486000A18486039.en. Downloaded on 30 August 2018.