The Galapagos Land Iguana is native to the Galapagos Islands, off the coast of Ecuador. It is formerly widely distributed on these islands, though its numbers are now greatly reduced (Mattison 1989, Cogger and Zweifel, 1998).
Biogeographic Regions: oceanic islands (Native ); pacific ocean (Native )
Distribution: Galapagos (James = Santiago, Indefatigable = Santa Cruz, Albermarle = Isabella, Narborough = Fernandina, South Seymour) (belongs politically to Ecuador)
Type locality: Galápagos?
The Galapagos Land Iguana is yellow or brown in color with spots throughout its ventrum and dorsum. A spikey dorsal crest runs along the neck and back. This is a large (>48 in), heavy bodied lizard, with thick back legs and smaller front legs. There are long, sharp claws on its toes. It has a short blunt head and pleurodont teeth. Its tail is quite a bit longer than its trunk. (Mattison 1989).
Habitat and Ecology
The lizards live in land burrows, which offer protection from the hot sun. Many islands on which the iguanas live are quite arid.
Terrestrial Biomes: scrub forest
The Land Iguana is largely a vegetarian. The prickly pear cactus (Opuntia) is a major food source; the lizard eats the cactus fruit and leaves by moving the cactus around in its mouth until all the spines are worked off (Mattison 1989).
Life History and Behavior
Status: captivity: 15.0 years.
Status: captivity: 7.3 years.
Lifespan, longevity, and ageing
These lizards have a mating ritual where the male agressively courts the female. Males defend territories around their burrows that both they and females use as shelter, and most courtship occurs around these burrows. Females are attracted to male's territories with burrows, but these burrows are not used for nesting. (Werner 1982).
Female Land Iguanas lay soft-shelled eggs with permeable shells. About 25 eggs are laid in burrows in moist sand or under leaf litter. On the arid, rocky island of Fernandina, females may travel more than 15 km to find good nest sites, sometimes within the crater of a dormant volcano. When places to lay eggs become scarce, competition between females occurs and some eggs already laid may be disturbed by another iguana (Werner 1983, Mattison 1989). Hatchlings appear in about three to four months, and may take about a week to dig out of the nest cavity (Terraquest 1996).
IUCN Red List Assessment
Red List Category
Red List Criteria
- Needs updating
- 1994Vulnerable (V)
- 1990Vulnerable (V)
- 1988Vulnerable (V)
- 1986Vulnerable (V)
The Galapagos Land Iguana is listed as a threatened species by the World Conservation Union (Baillie and Groombridge 1996). Threats include destruction of eggs and young lizards by introduced rats and cats, and destruction of food plants by introduced goats.
IUCN Red List of Threatened Species: vulnerable
Relevance to Humans and Ecosystems
No adverse effects.
This species was observed by Darwin early in the 19th Century; Darwin noted its similarity to iguanas on the South American mainland, as well as its obvious adaptations to local conditions. These and other observations of Galapagos wildlife contributed in part to Darwin's theory of evolution.
Today the Land Iguanas are an important part of the unique Galapagos fauna, and studies of their biology, as well as conservation programs, are continuing.
Galapagos land iguana
The Galapagos land iguana (Conolophus subcristatus) is a species of lizard in the family Iguanidae. It is one of three species of the genus Conolophus. It is endemic to the Galápagos Islands, primarily the islands of Fernandina, Isabela, Santa Cruz, North Seymour, Baltra, and South Plaza.
The Galapagos land iguana varies in morphology and coloration among different island populations. There are two taxonomically distinct forms of Conolophus inhabiting the western part of the islands (C. rosada and C. pallidus) and one in the central part (C. subcristatus). Its generic name, Conolophus, is derived from two Greek words: conos (κώνος) meaning "spiny" and lophos (λοφος) meaning "crest" or "plume", denoting the spiny crests along their backs. Its specific name subcristatus is derived from the Latin words sub meaning "lesser" and cristatus meaning "crested," and refers to the low crest of spines along the animal's back which is not as tall as in most iguana's.
Anatomy and morphology
Charles Darwin described the Galapagos land iguana as "ugly animals, of a yellowish orange beneath, and of a brownish-red colour above: from their low facial angle they have a singularly stupid appearance." The Galapagos land iguana grows to a length of three to five feet with a body weight of up to twenty-five pounds, depending upon which island they are from. Being cold-blooded, they absorb heat from the sun by basking on volcanic rock, and at night sleep in burrows to conserve their body heat. These iguanas also enjoy a symbiotic relationship with birds; the birds remove parasites and ticks, providing relief to the iguanas and food for the birds.
Diet and longevity
Land iguanas are primarily herbivorous; however, some individuals have shown that they are opportunistic carnivores supplementing their diet with insects, centipedes and carrion. Because fresh water is scarce on the islands it inhabits, the Galapagos land iguana obtains the majority of its moisture from the prickly-pear cactus that makes up 80% of its diet: fruit, flowers, pads, and even spines. During the rainy season it will drink from available standing pools of water and feast on yellow flowers of the genus Portulaca.
Galapagos land iguanas become sexually mature anywhere between eight and fifteen years of age, depending on which island they are from. Mating season also varies between islands, but soon after mating, the females migrate to sandy areas to nest, laying 2–25 eggs in a burrow 18 inches deep. The eggs hatch anywhere from 90 to 125 days later.
On South Plaza Island, where the territories of marine iguanas and land iguanas overlap, the two sometimes interbreed, resulting in a mixture of features from each species; resulting in what is known as a hybrid iguana. The most likely unions tend to be between male marine iguanas and female land iguanas. Despite their long separation time and their being two distinct species from different genera, the offspring are viable, although likely sterile.
It is estimated that between 5,000 and 10,000 land iguanas are found in the Galapagos. These iguanas were so abundant on Santiago Island at one time that naturalist Charles Darwin remarked when it was called King James Island that "...when we were left at James, we could not for some time find a spot free from their burrows on which to pitch our single tent". In the years since then, entire populations (including all the animals on Santiago Island) have been wiped out by introduced feral animals such as pigs, rats, cats, and dogs.
It has been suggested that a pink morph of the Galapagos population is actually a genetically distinct subpopulation. This would warrant a separate species designation for the pink subpopulation. Subsequent genetic analysis of the pink morphs have suggested that the subpopulation split off from the main C. subcristatus one at least five million years ago.
Beginning in the early 1990s the Galapagos land iguana has been the subject of an active reintroduction campaign on Baltra Island. These animals became extinct on Baltra by 1954, allegedly wiped out by soldiers stationed there who shot the iguanas for amusement. However, in the early 1930s, William Randolph Hearst had translocated a population of land iguanas from Baltra to North Seymour Island, a smaller island just a few hundred metres north of Baltra because he could not understand why no iguanas were present there. Hearst's translocated iguanas survived, and became the breeding stock for the Charles Darwin Research Station captive breeding program which has successfully reintroduced the species to Baltra and a number of other areas. Visitors today frequently see iguanas on both the runway of the Baltra airport or while they cross the road.
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