Spectacled caiman
Spectacled caiman | |
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In Llanos, Venezuela | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Archosauromorpha |
Clade: | Archosauriformes |
Order: | Crocodilia |
Family: | Alligatoridae |
Subfamily: | Caimaninae |
Clade: | Jacarea |
Genus: | Caiman |
Species: | C. crocodilus
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Binomial name | |
Caiman crocodilus | |
Native range (black) | |
Synonyms[5] | |
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The spectacled caiman (Caiman crocodilus), also known as the white caiman,
Taxonomy
The spectacled caiman was described by Carl Linnaeus in 1758, originally as Lacerta crocodilus.[2] It has since been redescribed several times, including as Caiman sclerops by Schneider in 1801.[5] Although Caiman crocodilus is now the scientific name of the species, some scientists still prefer using sclerops, as having crocodilus as the scientific name for a caiman may cause confusion.[9]
The spectacled caiman has four recognized subspecies:[7][10]
- C. c. apaporiensis (Medem, 1955), commonly known as the Rio Apaporis caiman; endemic to Colombia and possibly the Venezuelan Llanos.
- C. c. chiapasius (Bocourt, 1876); distributed in Mexico, Central America, and northern South America.
- C. c. crocodilus (Linnaeus, 1758), the nominate subspecies, commonly known as the spectacled caiman; found in various parts of South America, such as Venezuela, Trinidad, Tobago, Brazil, etc.
- C. c. fuscus (Cope, 1868), commonly known as the brown caiman; lives from Nicaragua to Colombia, Ecuador, and Venezuela.
The yacare caiman (Caiman yacare), while previously thought to be a subspecies of C. crocodilus, is now usually considered a separate species.[2]
The Rio Apaporis caiman was believed to have become extinct by 1981, when the last known specimen died in a zoo. However, a specimen was captured in an expedition by Colombian conservation biologist Sergio Balaguera-Reina in 2018.[11] Later, the subspecies was discovered again by wildlife biologist Forrest Galante for the television show Extinct or Alive in 2019 and identified by DNA sampling.[12][13][14] Galante has advocated for the Rio Apaporis caiman to be considered a distinct species, while Balaguera-Reina maintains its official status as a subspecies.
Characteristics
The spectacled caiman is a small to medium-sized crocodilian. Females generally grow to no more than 1.08 to 1.4 m (3 ft 7 in to 4 ft 7 in) (the lower size typical upon the onset of sexual maturity), but can rarely grow to nearly 2 m (6 ft 7 in). Adult males can regularly reach 1.5 to 1.8 m (4 ft 11 in to 5 ft 11 in) while large mature ones grow to 2.0 to 2.5 m (6 ft 7 in to 8 ft 2 in), although relatively few get to the upper size.[15] The maximum reported size for the species is 2.64 m (8 ft 8 in).[16] The body mass of most adults is between 7 and 40 kg (15 and 88 lb), with males typically being considerably heavier than females. Some males in the Llanos have been reported to grow to up to 58 kg (128 lb).[17]
The upperside of the species is mostly brownish-, greenish-, or yellowish-gray colored and has dark brown crossbands,[16] with a lighter underside. It has a greenish iris.[18] and wrinkled eyelids.[8] It changes color seasonally – during colder weather, the black pigment within its skin cells expands, making it appear darker.[19] The species has an enlarged 4th tooth, and the teeth in its lower jaw penetrate into a socket in its upper jaw. It has a long snout that tapers moderately, with an unexpanded tip.[20] Several ridges begin in front of its eyes and travel to the tip of its snout.[18] Its common name comes from a bony ridge between its eyes, which gives the appearance of a pair of spectacles.[21] The spectacled caiman is the most widely distributed New World crocodilian, and is the most geographically variable species in the Americas, making it a highly adaptable species.[22]
Biology and behavior
The spectacled caiman can move rapidly when threatened, but is usually immobile, resting on shores or partly in water. In the rainy season, males become aggressive and territorial.[17]
Hunting and diet
Usually hunting at night, the diet of the spectacled caiman varies seasonally.
Communication
The spectacled caiman uses nine different vocalizations and 13 visual displays to communicate with individuals of its species.
Reproduction
The spectacled caiman reaches sexual maturity from four to seven years old, at a length of 1.2 metres (3.9 ft) for females and 1.4 metres (4.6 ft) for males. Usually, the more dominant individuals mature more quickly. Specimens choose mates and engage in copulation from May to August, the wet season.[15] The females build nests as a mound of dense vegetation, in areas that are close to water but not at risk of being flooded. The nests are over 1 metre (3.3 ft) in diameter and can be 40 centimetres (16 in) high, but the exact size depends on the resources available. Eggs are laid in July and August; the species very rarely nests in the winter, as the temperature is too low for the eggs.[17][29] Clutch size is 22 on average, but can range from 14 to 40.[15] Larger females have been known to lay larger eggs compared to smaller females.[30] Females stay close to their nests during the incubation period, as several species, such as lizards in the genus Tupinambis, have been known to destroy nests and prey on the eggs.[15] White-nosed coatis and foxes also raid nests.[23] Flooding and human egg collecting can also be a threat to the nests.[17] In a study in the Central Amazonia assessing reproductive similarities between C. crocodilus and Melanochus niger, research found that they indiscriminately separate their nests at larger distances than other species in this family, most likely to avoid predation.[31]
Temperature is important to the developing eggs, so females build their nests in a way that insulates them from extreme temperature changes. As the vegetation in the nests decays, the nests produce heat which can keep the eggs about 5 °C (9 °F) warmer than if they were insulated by mud alone.[29] Heat not only incubates the eggs, but also determines the sex of the developing caimans (temperature-dependent sex determination). When the temperature inside the nest is about 32 °C (90 °F) or higher, the caimans become female, and otherwise become male.[32] Young hatch after 90 days,[21] with 20–25 percent of eggs hatching successfully.[17] They are yellow with black spots, a coloration which fades away as they grow older,[15] with a length of 20–23 centimetres (7.9–9.1 in).[17] Parents raise their young in crèches, with one female taking care of her own, as well as several others' offspring.[33] They take care of their young for 12–18 months.[10] Young are threatened by various predators, such as raptors (like hawks)[34] and wader birds (like herons),[23] causing most to die in their first year.[17] These juveniles are also preyed upon by large fish, large snakes (such as anacondas), and other crocodilians.[23]
Distribution and habitat
The spectacled caiman has the largest range of any caiman,[9] and of any New World crocodilian.[10] It is found in various countries throughout the Americas. It lives in Brazil, Colombia, Costa Rica, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Peru, Suriname, Trinidad and Tobago, and Venezuela, and may also be extant in Belize and Bolivia. It has been introduced to Isla de la Juventud in Cuba, Puerto Rico, and Florida in the United States;[2] in the latter, it is sometimes mislabeled as the American alligator (Alligator mississippiensis).[15] Invasive populations have become established in South Florida, with isolated records further north in the state.[33] It is intolerant to cold climates, so its range is unlikely to expand to further north than Florida.[35] It usually lives in forests, inland bodies of fresh water (such as wetlands and rivers), grasslands, shrublands, and savannas, but is very adaptable.[2] It prefers habitats with calm water containing floating vegetation, usually flooding and drying seasonally. It is most common in low-lying areas, but has been found at elevations of up to 800 m (2,600 ft).[17] In Brazil, the species lives in the rivers Amazon, Araguaia, Araguari, Itapicuru, Rio Negro, Paranaíba, Solimões, Tapajós, Tocantins, and Xingu.[8] It is able to live in human-inhabited areas.[18]
The adult population of this crocodilian is estimated to be in the millions and stable.[2] About four million spectacled caimans are found in Venezuela and surveys have shown that it is expected to increase.[19] This is an example of how well the species is able to adapt.[15] However, populations are not doing well in other countries, such as Peru.[19] The population in a single area can be determined the easiest by counting individuals in the dry season at night.[17]
Threats and conservation
The skin of the spectacled caiman is covered with
The spectacled caiman benefits from overhunting of competitive species which occupy the same home range, as this allows it to access resources normally lost to these other species. Specimens that have been introduced to Cuba, Puerto Rico, and the United States negatively impact the native animals there. They are believed to have been the main reason for the likely
Conservation programs for this species are used in many countries. The most common form of conservation is the use of cropping, which consists of manually reducing the numbers of several wild and abundant species. Long-term effects of cropping have yet to be discovered; more surveys have been recommended. Farming or ranching programs have also been used as conservation efforts for the species, but seem to be more expensive and possibly less effective.[15] A conservation program in Colombia, which existed from 2004 to 2006, bred spectacled caimans in captivity and released the young into the wild at one year old. A similar program released over 15,000 juveniles into wetlands from 2005 to 2009.[2] Previously, Colombia restricted the exportation of spectacled caiman skins to ones shorter than 1.2 metres (3.9 ft), but as of 2011 there are now only size limits for some individual pieces of the skin, rather than the overall size of the skin. These limits are less effective, as large skins could accord with the size limits if cut and trimmed.[36] According to the International Union for Conservation of Nature (IUCN), further surveys of the species would help with future conservation plans.[2]
The spectacled caiman is listed as a species of
References
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- ^ Franzen, Margaret Anne (2005). Huaorani resource use in the Ecuadorian Amazon. University of California, Davis. p. 181. Retrieved 3 April 2019.
- ^ a b "ITIS Standard Report Page: Caiman crocodilus". Integrated Taxonomic Information System. Retrieved 28 March 2019.
- ^ ISBN 978-1848262812. Retrieved 5 April 2019.
- ^ a b Triche, Nina (28 May 2003). "Caiman crocodilus (spectacled caiman)". Digimorph. Retrieved 3 April 2019.
- ^ a b c d e f Velasco, A.; Ayarzagüena, J. (2010). "Spectacled Caiman crocodilus" (PDF). In Manolis, S. C.; Stevenson, C. (eds.). Crocodiles. Status Survey and Conservation Action Plan (3 ed.). Crocodile Specialist Group. pp. 10–15. Retrieved 5 April 2019.
- ^ www.rewild.org https://www.rewild.org/news/rediscovery-of-lost-caiman-leads-to-new-crocodylian-mystery. Retrieved 14 March 2024.
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(help) - ^ "In the bombast of the American TV host, colonial science lives on". TheWire. 5 March 2020. Retrieved 5 March 2020.
- ^ Fusco, Thom (19 December 2019). "Nature Believe - extinct Rio Apaporis caiman rediscovered". Discovery Channel. Retrieved 19 December 2019.
- ^ Lindsay renick, Mayer (12 December 2019). "Rediscovery of lost caiman lead to new crocodilian mystery". rewild. Retrieved 12 December 2019.
- ^ a b c d e f g h i j k Britton, Adam. "Spectacled Caiman (Caiman crocodilus)". Crocodilian Species List. Retrieved 27 March 2019.
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- ^ a b c "Spectacled Caiman - Caiman crocodilus". World Association of Zoos and Aquariums. Archived from the original on 31 October 2013.
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- ^ Velasco, Alvaro; Ayarzaguena, Jose (2010). Spectacled Caiman (Caiman crocodilus). Venezuela: Fundación La Salle de Ciencias NaturalesApartado. p. 10.
- ^ a b c d e Terry, Kayla. "Caiman crocodilus (Common caiman, Spectacled caiman)". Animaldiversity.org. Retrieved 13 March 2022.
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- ^ Campos, Zilca; Magnusson, William E.; Sanaiotti, Tânia; Coutinho, Marcos E. (April 2008). "Reproductive trade-offs in Caiman crocodilus crocodilus and Caiman crocodilus yacare: Implications for size-related management quotas". Herpetological Journal. 18 (2): 91–96. Retrieved 30 March 2019.
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- ^ a b Webb, Grahame; Brien, Matthew; Manolis, Charlie; Medrano-Bitar, Sergio (6 May 2012). "Predicting total lengths of spectacled caiman (Caiman crocodilus) from skin measurements: A tool for managing the skin trade" (PDF). Herpetological Conservation and Biology. 7 (1): 16–26. Retrieved 14 April 2019.
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External links
- Media related to Caiman crocodilus at Wikimedia Commons
- Data related to Caiman at Wikispecies