The basic biology of Common Green Iguana has been studied in many portions of its wide range of distribution (México: Casas Andreu and Valenzuela López 1984, Alvarado et al. 1995; Honduras: Klein 1982; Costa Rica: Hirth 1963, Fitch and Henderson 1977, van Devender 1982; Panamá: Rand 1968a; Colombia: Müller 1968, 1972; Harris 1982; Muñoz et al. 2003; Venezuela: Rodda 1990, 1992; Rodda and Grajal 1990; Curaçao: Bakhuis 1982, van Marken Lichtenbelt and Albers 1993; Brazil: Ferreira et al. 2002, Campos and Desbiez 2013). In contrast to the majority of iguana species, Common Green Iguanas have colonized humid tropical rainforests and can be exclusively arboreal, descending to the ground principally for nesting. This species also inhabits other types of habitat beyond tropical rainforest, including dry forest, gallery forest, savannahs with few trees, and even xeric islands with exclusively shrub vegetation. Herbivory in Common Green Iguanas have been studied primarily from an ecophysiological point of view (Rand 1978; Iverson 1982; McBee and McBee 1982; van Devender 1982; Troyer 1984a, 1984b, 1984c; Govender et al. 2012), rather than from an ecological perspective (Benítez-Malvido et al. 2003). Iguana iguana is one of the few generalist herbivores of tropical forest canopies (Rand 1978), but even so, there is evidence they prefer to feed on certain plant species, not necessarily the most abundant (Rand et al. 1990, van Marken Lichtenbelt 1993, Lara-López and González-Romero 2002, Gómez-Carrasquillo et al. 2006, Campos et al. 2014). Consumption of snails and insects that occur on vegetation is probably incidental (Hirth 1963, Townsend et al. 2005). Consumption of dead animal flesh (Loftin and Tyson 1965, Arendt 1986, Anderson and Enge 2012) and faeces of conspecifics (Troyer 1984c) or other species (Campos et al. 2011) also has been documented. This behaviour may be related to maintaining an intestinal microbial fauna for fermentation of plant matter. Thermoregulation in juveniles and adults apparently also is tightly related to digestive processes (Wilhoft 1958; McGinnis and Brown 1966; Müller 1972; van Marken Lichtenbelt et al. 1993, 1997). In areas where it has been documented, the phenology of this iguana’s reproductive cycle is correlated tightly to the tropical wet and dry seasons. Males establish reproductive territories at the beginning of the dry season and females lay their eggs during a restricted period in the middle of this season, so that eggs begin hatching near the onset of the rainy season, a time when new leaves are abundant and easier for neonates to digest (Hirth 1963; Rand 1968a; Müller 1968, 1972; Fitch and Henderson 1977; Harris 1982; Klein 1982; van Devender 1982; Casas Andreu and Valenzuela López 1984; van Marken Lichtenbelt 1993; Muñoz et al. 2003). Because the climate varies seasonally between hemispheres, there is a clinal variation in the dates of mating, nesting, and hatching across the range of the species (Rand and Greene 1982). There is wide variability in body sizes of females nesting for the first time (between 295–425 mm SVL) and these were estimated between two and eight years of age (Zug and Rand 1987). Clutch sizes vary directly with body size, ranging from nine to 71 eggs (Rand 1984, Alvarado et al. 1995) and, in the majority of populations that have been examined, mean clutch size is near 35 eggs (Hirth 1963, Müller 1972, Klein 1982, Casas Andreu and Valenzuela López 1984, Rand 1984, but see Bakuis 1982, Muñoz et al. 2003). To date, only one nest per female in only one annual nesting season has been documented, although Rand and Greene (1982) speculated that some populations near the equator, where there are two well-defined dry seasons each year, might exhibit two reproductive seasons each year with some females nesting in both. Although not well-studied, survival rates in Common Green Iguanas appear low for both juveniles and adults. One study found that up to 60% of all nesting females die each year (Bock et al. 1985) and another estimated hatchling survivorship at 65.2% for three weeks (Knapp and Abarca 2009). Juvenile iguanas are preyed upon by crocodiles, caiman, and fish while swimming during their dispersal away from the nesting sites, and by other large lizards (for example, Basiliscus sp.), snakes, birds, and mammals when in their terrestrial habitat (van Devender 1982, Rivas et al. 1998, Knapp and Abarca 2009, Ribeiro Duarte 2010, Wehrle and Guzman 2012). Adults are vulnerable to attacks by snakes, raptors, owls, and a variety of mammals (Swanson 1950, Greene et al. 1978, Bessier et al. 2010). Adult females also are vulnerable to attack by crocodiles and caiman while swimming during migration to and from nesting sites and while they are excavating nest burrows (Dugan et al. 1981, Bock and Rand 1989, Platt et al. 2010)
In addition to commercial iguana farms, there are multiple projects within the range of the Common Green Iguana where they are raised in captivity as part of a conservation strategy (headstarting). One of the most well-known of these projects is Fundación Pro Iguana Verde, initially under the administration of the Smithsonian Tropical Research Institute in Panamá (Werner 1987, 1991). The idea was to develop economic strategies to make land use more sustainable (Werner and Miller 1984, Miller 1987) by permitting rural peoples to raise iguanas for food and wild release. Several communities participated in trial releases as part of this project, where juveniles were reared until attaining harvestable sizes, offering an additional source of protein to participating families without requiring the removal of individuals from natural populations (Cohn 1989). Similar projects were functioning in Costa Rica, where they also operate an ecotourism attraction, conduct environmental education, and continue releasing headstarted iguanas in natural habitats (Escobar et al. 2010). In addition, there are dozens of other projects that raise iguanas for conservation strategies in Central America, almost all supported by local governments and NGOs (Stephen et al. 2011). However, recent analyses have concluded that these projects are not economically viable and their impact on the natural populations has been minimal (Eilers et al. 2002, Stephen et al. 2011). These projects may play an important environmental education role, but apparently the repopulation efforts have not been very effective, and there is no evidence that they are helping to reduce the harvest levels in natural populations where they operate. This species is listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and found in several protected areas.
CLASS : Reptilia
ORDER : Squamata
FAMILY : Iguanidae
GENUS : Iguana
SPECIES : Common Green Iguana (Iguana iguana)
Conservation status : Least Concern
Update : 11 April 2017
