Mona ground iguana

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Mona ground iguana

Critically Endangered (IUCN 3.1)[1]
CITES Appendix I (CITES)[2]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Iguania
Family: Iguanidae
Genus: Cyclura
Species:
C. stejnegeri
Binomial name
Cyclura stejnegeri
Noble
, 1916
Synonyms

Cyclura cornuta stejnegeri (

Noble
, 1916)

The Mona ground iguana (Cyclura stejnegeri) is a critically endangered species of

Mona Island, Puerto Rico. It is one of the island nation's few large land animals, and it is the largest endemic terrestrial lizard in the country, and one of the biggest rock iguanas within the Antilles. It was previously considered a subspecies of the rhinoceros iguana
(Cyclura cornuta).

Taxonomy

The Mona ground iguana belongs to the genus

Leonhard Hess Stejneger, who, when writing his Herpetology of Porto Rico in 1902, suspected the rhinoceros iguanas of Mona Island might be slightly different in scale count than those in Haiti, although he was unsure.[5]

In 1993 Robert Powell suggested that all three subspecies of the rhinoceros iguana could be seen as distinct species, if the word "species" was redefined to mean any population which was separated from another population. Although it does not appear to be distinct from the nominotypical subspecies morphologically, in a 1999 article, Powell again recommended recognizing this population as a different species, based on what he had said in 1993.[4] Some authorities have decided to follow Powell.[6][7] Still, others consider it a regional variant of the parent species, C. cornuta.

Description

The Mona ground iguana is a large-bodied, heavy-headed lizard with strong legs and a vertically flattened tail, which is capable of reaching 1.22 m (4 ft 0 in) in length (from

Juveniles differ from adults in that they have gray transverse bands across their bodies.[8]
These bands last until they are sexually mature at about three years of age.

Males possess bony, prominent tubercles on their snouts resembling horns, adipose pads in the form of a helmet on the

Mona Island studying C. stejnegeri, suggested that the horns, along with lateral spines and prominent parietal bulges, function as protective armor against sharp rocks or as defensive tools to facilitate the escape of males from the grasp of one another.[9][10][11]

Habitat

Mona ground iguanas are

diurnal and spend most of the day basking in the sun conserving energy. Mona ground iguanas are endemic to Mona Island; they are scattered through the entire island, though the southwest part of the island is only used during the nesting season. They live a considerable portion of their lives underground, and are usually found in talus slopes, caves
and sinkhole depressions. The average depth underground that they can be found is 1.5 m (4 ft 11 in).

Reproduction

Mona ground iguana hatchling

Although Mona ground iguanas use the whole island as their habitat, only 1% of the territory, located on the southwest coast, is suitable for nesting because it contains loose sand, and receives direct sunlight. The females bury their eggs in the sand, and the sunlight incubates the eggs. Males reach sexual maturity at a size of 28–31 cm (11–12 in) in length from snout to vent, usually in their third to fourth year, while females mature one year later at a size of 35–40 cm (14–16 in).

Nesting season begins in the second week of June. Usually, one female mates with more than one male in the two weeks the

mating season lasts. Copulation may last from 15 sec to 2 mins and 15 sec. One month later, nesting begins. Females will dig a tunnel 0.91 m (3 ft) long located one to two feet underground, where they deposit from five to 19 eggs, with 12 being the average. They will guard their nests for several days, but provide no parental care for the hatchlings, which hatch three months later. Hatchlings measure, on average, 32 cm (13 in) and weigh 73.7 g (2.60 oz) and grow at a rate of 5.23 cm (2.06 in) per year.[12]

Diet

Mona ground iguanas, like most Cyclura species, are primarily

herbivores of their ecosystems, they are essential for maintaining the balance between climate and vegetation.[4][15] Their diets are very rarely supplemented with insect larvae, crabs, slugs, dead birds, and fungi; individual animals do appear to be opportunistic carnivores.[4][9] Fewer than a dozen animal species and 71 plant species are found in the Mona ground iguanas' diets.[9] Mona ground iguanas eat the caterpillar of sphingid moths.[4] These larvae feed on poisonous plants and are aposematically colored and avoided by other predators.[16]

Endangered status

Population numbers are estimated at 1,500 with lower densities than similar iguana-inhabited islands in the West Indies. Immature iguanas are scarce and represent only 5–10% of the population, revealing that the population is aging and in decline.[17]

Reasons for decline

The biggest threat to C. stejnegeri are invasive species; feral pigs pose the most serious threat, as they root up iguana nests, and like most Cyclura species, the Mona ground iguana nests communally and at high density.[13][17] Introduced goats and pigs are a major competitor for food and overbrowsing by goats also leads to loss of protective cover from birds of prey such as the osprey and predation of juveniles by feral cats.[13][17]

Recovery efforts

A

Toledo Zoo, and the University of Puerto Rico in 1999, to aid in the recovery of the Mona ground iguana.[18] From within the safety of this program, the iguanas are reared until they are large enough to survive in the wild, and predators, such as pigs and feral cats, are no longer a threat.[15] The facility also carries out health screening prior to the release of specimens.[15] This health screening has been used to provide baselines of the normal physiologic values of the species, identifying potential future problems due to parasites, diseases, etc. which might threaten the population.[17]

See also

References

  1. . Retrieved 19 November 2021.
  2. ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  3. ^ Barbour, Thomas & Noble, G. Kingsley (1916). "A revision of the lizards of the genus Cyclura". Bulletin of the Museum of Comparative Zoology at Harvard College. 60 (4): 139–164.
  4. ^ a b c d e f Powell, Robert (1999), "Herpetology of Navassa Island, West Indies" (PDF), Caribbean Journal of Science, 35 (1–2): 1–13, archived from the original (PDF) on 20 July 2011, retrieved 2007-09-09
  5. ^
    Stejneger, Leonhard (1902), The Herpetology of Porto Rico
    , New York: Rept. U.S. Nat. Mus, pp. 549–724
  6. ^ "Cyclura stejnegeri Barbour and Noble, 1916", Integrated Taxonomic Information System, 2001, retrieved 2007-10-16
  7. ^ "Cyclura stejnegeri". The Reptile Database. Retrieved 2021-07-07.
  8. ^ Rivero, J.A. 1978. Los anfibios y reptiles de Puerto Rico. Universidad de Puerto Rico, Editorial Universitaria, Mayaguez, Puerto Rico. 152p. 49 plates. (in Spanish)
  9. ^ a b c Wiewandt, Thomas A. (1977). Ecology, behavior, and management of the Mona Island ground iguana Cyclura stejnegeri (Ph.D.). Cornell University.
  10. ^ a b c Byrd, Dan; Byrd, Sylvia (1996), "The Rhinoceros Iguanas of Mona Island", Reptiles: Guide to Keeping Reptiles and Amphibians, 4 (1): 24–27
  11. ^ Derr, Mark (2000-10-10), "In Caribbean, Endangered Iguanas Get Their Day", New York Times Science Section
  12. ^
  13. ^ Powell, Robert (8 January 2000), "Horned Iguanas of the Caribbean", Reptile and Amphibian Hobbyist, 5 (12)
  14. ^
  15. ^ Perez-Buitrago, Nestor (2005), "Successful Release of Head Start Mona Island Iguanas" (PDF), Iguana Specialist Group Newsletter, 8 (1): 6, archived from the original (PDF) on 2007-08-12

External links