The Genus Cyclura cychlura, Cyclura nubila, and Cyclura rileyi. All species are on the IUCN Red List of Threatened Species. Four species are critically endangered, three are endangered, three are vulnerable and one is extinct. species are located on islands in the West Indies, where they are the largest surviving native land vertebrate. species are primarily herbivorous, though they will eat animal matter that is easy to obtain such as such as insects, land crabs, and rotting flesh. As iguanas are good climbers, it is not uncommon to find them in trees. Rock iguanas have no known natural predators, although feral domestic animals are now one of the largest threats to these iguanas. This is due to predation by feral animals or competition for resources with them. (Blair, 2000) (Blair, 2000; Schwarts and Carey, 1977)contains 11 recognized species. Since a taxonomic review of Cyclura in 1977, five of the described subspecies were promoted to species (Schwartz and Carey, 1977). There are 8 recognized subspecies in the species
All populations of rock iguanas are endemic to the islands of the West Indies. They are spread widely throughout the islands, with no specific island as a hotspot (Blair, 2000). (Blair, 2000)
Rock iguanas are found in xerophytic scrub forests, sandy areas, and mangrove forests on islands in the West Indies (Beovides-Casas and Mancina, 2006). They use caves and crevices that had been formed in heavily eroded limestone as retreats and will sometimes dig burrows in sandy areas. Adults are mostly terrestrial while young can often be found in trees (Blair, 2000). (Beovides-Casas and Mancina, 2006; Blair, 2000)
Sinceis such an endangered genus, most research has been on these iguanas in captivity. In the wild, rock iguanas are mostly polygamous, but there are instances that have been recorded where they are promiscuous or monogamous (Blair, 2000). Rock iguanas are territorially aggressive and solitary until mating season. During mating season, males expand their territories to overlap with as many females as possible and will attack other males that enter their territory to monopolize females. Smaller males normally flee while chased by larger individuals. Physical fights are uncommon and generally only occur between similar sized individuals. Fights that do occur are vicious. Wounds that can result from fights include internal hemorrhaging, flesh wounds, tearing of the skin, in some cases death (Hunsaker II and Burrage, 1969). Females are also aggressive toward each other and will determine a hierarchy.
Copulation begins with a series of head bobs from the male toward the female, after which the male will position himself behind the female. He then will grasp the female on the nape of the neck attempting to restrain her to position himself for intromission. This process takes about 30 to 90 seconds but rarely any longer (Blair, 2000). (Alberts and Lemm, 2012; Blair, 2000; Hunsaker II and Burrage, 1969)
Before fertilization, females increase food intake and body temperature to reach optimal metabolic rates to make eggs. During copulation, the female will often end up with injuries to the nuchal crest or other parts of her body if the male is overly aggressive. After copulation, the male is no longer involved in the parenting process. Several days before oviposition, females will go outside their normal ranges to find a suitable place to dig a nesting burrow. These burrows are deep, spacious (ranging from 0.4 meters to 1.5 meters long), and warm (29.4 to 30.6 °C) (Blair, 2000). In captivity, nesting is the biggest hurdle in successful breeding. If the nest is not dug properly or the female holds onto the eggs for too long because the nest is not to the female’s liking, the eggs will not hatch. If the female is satisfied she will then cover the nest and often protect it from predators for up to several weeks. Once the eggs hatch, the hatchlings are independent and go on to live solitary lives. Sadly, in the wild juvenile (Alberts and Lemm, 2012; Blair, 2000)species experience high mortality rates that can reach nearly 100% in some populations due to natural predators as well as introduced predators (Alberts and Lemm, 2012; Blair, 2000).
Cyclura nubila lewisi named Godzilla, having lived to 69 years of age in the Gladys Porter Zoo in Texas. Survival rates are lowest for juveniles due to predation by natural predators such as snakes and birds, as well as introduced predators such as feral cats and dogs. These rates can range from 22 to 97% depending on both the population and its location. Generally, chances of survival increase with increase in size and maturity (Alberts and Lemm, 2012). (Alberts and Lemm, 2012; Blair, 2000)contains some of the longest living lizard species. It is estimated that these lizards can live 25 to 40 years in the wild (Blair, 2000). Captive members have been known to exceed that range because of the high level of maintenance provided in captivity. The longest living member of on record is a male member of the species
Rock Iguanas are diurnal, sedentary, and solitary lizards that generally only interact during mating. Many intraspecific behaviors are demonstrated during mating. Outside of mating season, both males and females establish dominance hierarchies. In males, dominance is associated with size of the head and body, display behaviors, testosterone levels, territory size, and proximity to females. In females, dominance is mostly associated with size (Alberts et al., 2002). Dominant individuals may attack any intruders in their territory after warning them with a series of head bobs. (Alberts and Lemm, 2012; Alberts, et al., 2002)species are independent and solitary as soon as they hatch. Hatchlings will often spend the first few months of their lives living in the trees to avoid ground predators but will still sometimes fall prey to birds and snakes. When rock iguanas are active, their time is primarily spent foraging, traveling as far as 300 to 500 meters to reach certain forests to feed in (Alberts and Lemm, 2012).
Rock iguanas use both chemical and visual communication when interacting with other rock iguanas and more specifically each species. These iguanas excrete a protein/lipid mixture from their femoral pores that is used for attracting mates as well as marking territory. They use both their tongue and their Jacobson’s organ for chemoreception of different scent markers from pheromones, or even from scat of conspecifics. The most important visual signal used in rock iguanas is the head bob, which is a when the head is raised then lowered in a species-specific pattern. The head bob is used in territorial maintenance and in mating. It is often the first warning intruders or predators will get before any kind of aggression occurs. Another form of visual signaling is body posturing. Body posturing is used in both aggressive encounters and submissive displays. In aggressive encounters, large males will turn their bodies sideways, stand high on their feet and inflate their bodies with air to appear as large as possible. In submissive displays, females or small males will drop their bodies as close to the ground as possible with the base of the tail raised. These visual signals are a good indication of the dominance hierarchy (Alberts and Lemm, 2012). (Alberts and Lemm, 2012)
Rock iguanas are primarily herbivorous. Their diet includes flowers, fruit, stems and leaves of plants from around 105 endemic plant species of the West Indies. They also opportunistically consume animal matter. This includes carrion, insects, land crabs, and skin flakes and feces of conspecifics (Alberts and Lemm, 2012; Pasachnik and Martin-Velez, 2017). (Alberts and Lemm, 2012; Pasachnik and Martin-Velez, 2017)
Since adult rock iguanas are the largest land vertebrates on their islands, they have few natural predators. However, hatchling and juvenile iguanas have quite a few predators. Natural predators for young rock iguanas include birds, snakes, and in one recorded instance, barracuda. Introduced species are the biggest threat to (Alberts and Lemm, 2012; Blair, 2000)species. Dogs, cats, and mongooses prey heavily on rock iguanas and have caused extinctions of some populations. Other introduced species, such as pigs, raccoons, rats, and mice also eat eggs, kill hatchlings and adults, and destroy habitat. When confronted by predators, rock iguanas exhibit a fight or flight response. They use aggression signals like head bobs or body inflation to scare away predators and will charge if cornered. Humans also historically hunted rock iguanas as a food source (Alberts and Lemm, 2012; Blair, 2000).
Rock iguanas are seed dispersers for native plants (Alberts and Lemm, 2012). (Alberts and Lemm, 2012)
Rock iguanas have been known to raid gardens or farms to eat vegetation, but is so rare that economic impact of this is negligible. (Alberts and Lemm, 2012)species pose no physical threat to humans unless provoked (Alberts and Lemm, 2012).
Species in the genus (Alberts and Lemm, 2012)are some of the most endangered lizard species in the world. Of the 16 currently recognized species and subspecies, 5 are endangered and 8 are critically endangered, according to the IUCN Red List of Threatened Species. The decline in species is directly related to European settlement of the West Indies. As human populations increased, habitat loss and degradation increased dramatically. This is due to human expansion and the introduction of feral livestock on the islands. Increases in the industries of limestone mining, agriculture, timber extraction and land clearing for tourist resorts and housing developments have reduced natural habitats to mere fractions of pre-settlement sizes (Alberts and Lemm, 2012).
Domestic and commensal animals that settlers brought with them have also had devastating impacts on rock iguana populations. Feral and domestic livestock, including goats, burros, donkeys, sheep, and cattle, compete with rock iguanas for food, alter local vegetation composition, prevent regeneration of plants and even trample on nests and burrows causing collapse of nests or compaction of soils to the point at which they are no longer suitable for nesting (Alberts and Lemm, 2012). (Alberts and Lemm, 2012)
Predation on rock iguanas by introduced domestic and commensal animals is also a significant threat. Having evolved with no natural predators, the introduction of feral cats, dogs, pigs, mongooses, and rats has devastated rock iguana populations. Dogs are capable of killing and consuming adults of even the largest species. Although cats are more likely to prey on hatchlings and juveniles, cats can kill all age classes of some of the smaller species. Pigs and rats have less destructive effects on adult iguanas, they have devastating effects on nests by feeding on eggs (Alberts and Lemm, 2012). (Alberts and Lemm, 2012)
Direct human interaction with rock iguanas has had negative effects on iguana populations. Illegal hunting and poaching is less severe than habitat loss and predation by introduced animals, but still has drastic results. Interaction with tourists is even less severe, but still a problem. Tourists walking through nesting areas can collapse nesting chambers. An emerging threat is tourists feeding iguanas inappropriate food items. This not only leads to increased intraspecific aggression and disruption of natural social systems, but can lead to dietary shifts that can result in medical consequences. Human presence with the iguanas is also making the iguanas less wary of humans. This loss of wariness makes hunting and poaching easier. With increased tourism and human population growth, more iguanas are killed due to vehicular traffic on roads (Alberts and Lemm 2012; Hines, 2011). (Alberts and Lemm, 2012; Hines, 2011)
Numerous conservation programs are in place to protect these endangered lizards. Habitat protection through the establishment of both protected areas and parks is a means to prevent further habitat loss. This includes restricting access to beaches and forests where rock iguanas live. Another action that is being taken is to control populations of invasive mammals. Efforts are being made to trap and eradicate feral pigs, cats, dog, rats, and mongooses. Some of the conservation actions are specifically focused in increasing population sizes. One action is called headstarting. This is when eggs laid in the wild are collected and brought to safe facilities. There, the hatchlings are raised until they are large enough to fend for themselves, and released back to where they were collected, giving them a “head start” in the race against predators. Another action is the introduction of translocation programs. These programs move groups of iguanas to unoccupied habitats. This is especially effective for populations that are restricted to small areas and in turn vulnerable to extinction events (Alberts and Lemm, 2012). (Alberts and Lemm, 2012)
Riley Magidow (author), Colorado State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
living in the southern part of the New World. In other words, Central and South America.
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
parental care is carried out by females
union of egg and spermatozoan
an animal that mainly eats leaves.
A substance that provides both nutrients and energy to a living thing.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
an animal that mainly eats fruit
An animal that eats mainly plants or parts of plants.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
An animal that eats mainly insects or spiders.
fertilization takes place within the female's body
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
animals that live only on an island or set of islands.
Having one mate at a time.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
chemicals released into air or water that are detected by and responded to by other animals of the same species
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
having more than one female as a mate at one time
an animal that mainly eats dead animals
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
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