Ameiva ameiva

Giant ameivas are found in Central and South America. They are found from the eastern coast of Brazil through the interior portions of central South America, to the west coasts of Columbia, Ecuador, and Peru. They are found as far south as the northern portions of Argentina, through Bolivia and Paraguay and as far north as French Guiana, Suriname, Guyana, Trinidad, Tobago, and Panama. Recently they have been introduced to areas of Florida. ("Scientific and Standard English Names", 2001; Biazquez, 1996; Sartorius, et al., 1999)

Giant ameivas are found in varied habitats, such as cerrado and northeastern caatinga in Brazil and Amazonian savannah and forests. They seem to prefer disturbed rain forests that have recently been harvested. (Biazquez, 1996; Colli, 1991)

Giant ameivas are medium-sized lizards with a body mass of about 60 g and a typical snout to vent length of 120 to 130 mm. Snout-vent lengths have been recorded as high as 160 mm in females and 180 mm in males. Cranial width averages 18 mm. Giant ameivas have femoral pores on the ventral side of the hind legs. Pore size is similar in both males and females, at about 1 mm in diameter. However, males have a single row of pores, about 17 to 23, running down the leg, whereas females have 16 to 22. Femoral pores are easy to see and the scales that hold them are specialized. This specialization helps in identifying the difference between those and other scales in the surrounding area of the hind leg. The rest of their body is covered with smooth scales. Coloration in both males and females is the same. However, juveniles differ in color from adults. Their backs have lines running the length of their body, colored yellow in adults and white in juveniles. Apart from these lines covering the dorsal portions of their body, the rest of their coloring is a dark brown. Their ventral side is ivory. (Biazquez, 1996; Colli, 1991; Imparato, et al., 2007; Sartorius, et al., 1999; Vitt, 1991)

Females carry their eggs for a short period of time and tend to stay in their burrows during this time. Once eggs are laid, incubation time is about 5 months, with offspring usually hatching at the beginning of the rainy season. Juvenile males tend to grow faster than their female counterparts. Maturity is acheived when snout-vent length reaches 100 mm, occurring at about 8 months after hatching for both males and females. (Colli, 1991; Vitt, 1982; Vitt, 1991)

There is little information on mating systems of Ameiva ameiva. The Ameiva plei mating system has been observed. This species is similiar to Ameiva ameiva in size and the environments in which they live, so their reproductive biology may be similar. Ameiva plei males tend to guard females during sexual encounters. However, males that did not guard females did not mate. Males in this species that were larger tended to mate more as they won over the most females.

Giant ameivas reproduce by laying eggs in clutches, which vary in size regionally. Although little data exist from most regions, data have been collected from caatinga and cerrado habitats of Brazil. Clutch size can range from 3 to 11. Clutch sizes tend to be larger in cerrado, averaging 6.4 +/- 0.2 (Colli, 1991). Clutch sizes in caatinga average 5.7 +/- 0.164 (Vitt, 1982). Clutch size is directly related to snout-vent length of the female - larger females produce more eggs per clutch. In cerrado, females can lay up to 3 clutches per reproductive season. However, in caatinga giant ameivas may reproduce throughout the year. The reproductive habits of Ameiva ameiva are based on rainfall. In areas where rainfall is constant or unpredictable throughout the year, reproduction is year-round. In areas where there is a distinct dry season, reproduction only occurs during the rainy seasons. This is thought to be the result of lack of food for both adults and juveniles during dry seasons. (Colli, 1991; Vitt, 1982)

There is little information on parental investment in this species. However, females invest heavily in supplying their eggs with nutrients before they are laid and males invest energy in mate guarding during mating.

No data exist about the lifespan of Ameiva ameiva in the wild. However, based on small sample sizes, individuals are known survive up to 4.6 years. The Index of Scientific Binomials indicate their observed specimen lived up to 2.8 years in captivity. ("Index of Scientific Binominals", 2002; Bowler, 1975)

Giant ameivas are solitary and diurnal. Not much is known about their behavior.

Giant ameivas are not territorial. However, they do have a home range which overlaps with other individuals. Data are not available for home range size of Ameiva ameiva. In a similar species, Lewis and Saliva (1987) report that the home range size of Ameiva exsul is based on size and sex of the lizard. Average male home range size was 376.8 square meters, and female home range was on average 173.7 square meters based on a data set from 13 males and females. Home range size may be similar in Ameiva ameiva. (Lewis and Saliva, 1987; Simmons, et al., 2005)

Femoral glands located on the ventral underside of the hind legs of Ameiva ameiva play a role in establishing territory size. Femoral glands also play a role in various sexual behaviors. These femoral glands produce semiochemicals which influence inter- and intra-specific communication. Although these semiochemicals are not well understood in Ameiva ameiva, they affect defense of territory and self, predation, territorial markings, and parental care. (Imparato, et al., 2007; Imparato, et al., 2007)

Giant ameivas are active foragers. Their diet varies regionally and seasonally and consists mainly of insects. The most common animals found in their diet are grasshoppers, butterflies, beetles, roaches, larvae, spiders, and termites. They have also been known to eat other species of lizards. What they eat is proportional to their snout-vent length; as they grow their prey becomes larger. (Magnusson, 1987; Boyden, 1976; Magnusson, 1987)

Predators of giant ameivas consist of a wide variety of birds and snakes. Unlike other species of lizards found throughout South America, they do not sit and wait for their prey. Their main method of avoiding predation is escape and their body shape is designed for rapid speed, allowing them to avoid predators in the open areas where they forage. Common predators of Ameiva ameiva include green snakes (Philodryas nattereri), roadside hawks (Buteo magnirostris), American kestrels (Falco sparverius), Guira cuckoos (Guira guira), chalk-browed mockingbirds (Mimus satturninus) and coral snakes (Micrurus frontalis). Giant ameivas are poorly adapted to introduced predators, such as mongooses (Herpestes javanicus) and house cats (Felis catus). (Colli, 1991; Maffei, et al., 2009; Shepard, 2007)

Giant ameivas are hosts for a wide variety of microorganisms. Common parasites include Plasmodium tropidury, Lainsonia, Hemolivia petit, Choleoeimeria carinii, Acroeimeria pintoi, and Isospora ameiva. Often these invasive parasites will damage organs such as the gall bladder, liver, kidneys, lungs,and spleen. Parasites also have been found in saliva and feces of this lizard. Many of the parasites found in the feces originate in the gut. Additionally, parasites invade epithelial cells. (Kaplan, 1995; Lainson and Paperna, 1999; Lainson, et al., 2003)

Although these species can carry disease and can be aggressive, people keep them as pets. Furthermore, giant ameivas tend to prefer cleared environments such as crop fields. Because their diet consists mainly of arthropods, they can help to keep pest populations under control. (Everard, et al., 1979; Kaplan, 1995; Sartorius, et al., 1999)

Giant ameivas are known carriers of the bacteria Salmonella, including strains that can infect humans. In Grenada, according to Everard et al. (1979), half of all specimens collected carried Salmonella. In Panama, giant ameivas had the highest percentage occurrence of Salmonella of all 447 specimens examined (Kournay, 1981). (Everard, et al., 1979; Kourany and Telford, 1981)

Currently giant ameivas are not considered threatened. There are no efforts at this time to actively conserve this species.