''Chelonoidis niger vandenburghi'', also known as the Volcán Alcedo giant tortoise, the Alcedo Volcano giant tortoise or the Alcedo giant tortoise, is a subspecies of

Galápagos tortoise The Galápagos tortoise or Galápagos giant tortoise (''Chelonoidis niger'') is a species of very large tortoise in the genus ''Chelonoidis'' (which also contains three smaller species from mainland South America). It comprises 15 subspecies (13 ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...

to the Galápagos archipelago in the equatorial eastern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''vandenburghi'' honours American

herpetologist Herpetology (from Greek ἑρπετόν ''herpetón'', meaning " reptile" or "creeping animal") is the branch of zoology concerned with the study of amphibians (including frogs, toads, salamanders, newts, and caecilians (gymnophiona)) and r ...

John Van Denburgh John Van Denburgh (August 23, 1872 – October 24, 1924) was an American herpetologist from California (who also used the name Van Denburgh in publications, hence this name is used below). Biography Van Denburgh was born in San Francisco and enr ...

Taxonomy

This tortoise is a subspecies of ''Chelonoidis niger'', and is sometimes considered to be a distinct species itself.

Description

Male tortoises grow to about 129 cm and females to about 90 cm in length, with domed

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the und ...

Behaviour

The tortoises spend most of the day feeding, resting, or congregating in muddy pools. They sleep in the open at night. Adults migrate seasonally, travelling along the rim of the volcano's

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber ...

and descending to the lower slopes to graze on new vegetation after wet season rains.

Feeding

The tortoises feed on grass, leaves, forbs, sedges, fruit and lichens, obtaining water from their diet and pools of rainwater.

Breeding

Male tortoises compete with each other by extending their necks, gaping, biting and pushing. They utter loud guttural noises while mating. Females start nesting in May and June at the end of the wet season, laying clutches of 6–26 eggs in soft soil. Juvenile tortoises tend to stay at lower, warmer, elevations for the first 10–15 years of their lives

Distribution and habitat

The tortoise's range is limited to an area of 476 km² on the Alcedo Volcano on the central part of Isabela Island. There it inhabits deciduous and evergreen forests as well as humid

grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...

Conservation

The tortoise population is estimated to comprise some 6,300 individuals, a decline of 84% since 1840, and the subspecies is considered to be

Vulnerable Vulnerable may refer to: General * Vulnerability * Vulnerability (computing) * Vulnerable adult * Vulnerable species Music Albums * ''Vulnerable'' (Marvin Gaye album), 1997 * ''Vulnerable'' (Tricky album), 2003 * ''Vulnerable'' (The Used album) ...

. The tortoise population formerly suffered through predation and trampling of eggs and hatchlings, as well as habitat degradation, by introduced animals including pigs, donkeys and goats. Volcanic eruptions have also affected the tortoises and their habitat, with a major eruption of Alcedo 100,000 years ago thought to be the cause of the subspecies' low

genetic diversity Genetic diversity is the total number of Genetics, genetic characteristics in the genetic makeup of a species, it ranges widely from the number of species to differences within species and can be attributed to the span of survival for a species. ...

References

{{Taxonbar, from= Q12745316 vandenburghi Subspecies Turtles of South America Endemic reptiles of the Galápagos Islands Reptiles of Ecuador Reptiles described in 1930