Agama agamaCommon Agama, Rainbow Lizard

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Geographic Range

Found in most of sub-Saharan Africa (Harris 1964).

Habitat

Rainbow lizards can occupy urban, suburban and wild areas that supply enough vegetation for reproduction and insects for food.

Physical Description

The agama lizard is characterized by its whitish underside, buff brown back limbs and tail with a slightly lighter stripe down the middle and six to seven dark patches to the side of this stripe. There is some sexual dimorphism. The subordinate males, females, and adolescents possess an olive green head. A blue body and yellow tail and head characterize the dominant male. A. agama has a large head separated from the body, a long tail, well-developed external ear openings and eyelids. This lizard also has acrodont, heterodont teeth. The lizard possesses both caniniform incisors for grasping and molariform cheekteeth for crushing. The maximum size for male lizards is twenty-five centimeters and female lizards is twenty centimeters (Harris 1964).

Reproduction

Females reach sexual maturity at age fourteen to eighteen months, males at two years. A. agama reproduces during the wet season although they are capable of reproducing nearly year round in areas of consistant rainfall(Porter et al. 1983). The male will approach the female from behind and head bob to her. If she accepts then she will arch her back with her tail and head raised. The male walks to her side and grasps her neck and puts his leg on the female's back, the pair swivel 90 degrees in order to bring their cloacas together and thrusts his tail onto her cloaca inserting his right or left hemipenes (depending on side location). This mating ritual usually lasts one to two minutes when the female will scurry away and the male also after several minutes (Harris 1964).

The female lays her eggs in a hole she digs with her snout and claws. The hole is five centimeters deep and is found in sandy, wet, damp soil that is exposed to sunlight nearly all day and covered by herbage or grasses. The eggs are usually laid in clutches ranging from five to seven ellipsoidal eggs. A. agama is a thermoregulated embryo species resulting in all males at twenty-nine degrees Celsius and all females at twenty-six to twenty-seven degrees Celsius (Crews et al. 1983). The eggs will hatch within eight to ten weeks. Hatchlings will be between 3.7 and 3.8 centimeters snoutvent plus their 7.5-centimeter tail. They will almost immediately start eating rocks, sand, plants, and insects. The adolescent will remain solitary for the first two months and by four months live in a gregarious group with a dominant male (cock), several females and some subordinate adolescent males (sub-males). The dominant male has mating distinction within his territory. If a sub-male or intruder tries to mate with his females then there is a challenge or fight. To gain territory males must establish a new territory with no cocks or dispose of the current cock (Harris 1964).

Behavior

The agama is mostly a docile lizard except for a cock who defends his territory. There are several identifiable behaviors in this species (head nod, head bob, challenge display, threat display, fighting, and basking). The head nod is when A. agama repeatedly raises and lowers his head, usually seen at the end of movements, possibly to show cock position of individuals. Head bobbing, also known as push-ups, is the raising and lowering of the head and chest. This is done in an alert posture, it also occurs in the reproductive behavior of the cock. Shown to females when in reproductive colors, one to two begins courtship. The challenge display is shown by the cock to intruding males or sub-males showing reproductive color. This is only seen in territory situations. The threat display is the rapid up and down movement of the head with the gular sac fully extended. The whole body raises and lowers.

During fighting males display different colors, usually a dark brown head and a pale blue-grey gular pouch is displayed to show intention (Harris 1964). Fighting is a series of bluffs, threats and combat. The challenge occurs when a sub-male or intruding male of reproduction color comes into a territory. The resident cock will challenge from a display post showing the gular pouch while head bobbing. The intruder will react by retreating or staying and displaying. If the intruder stays then the cock will charge to within two feet and will change colors and threaten again, he will then rush within six inches and will side hop with mouth open. The males will then reverse directions and strike each other with their tails.

Basking occurs mainly in the morning between ten and noon, when A. agama has a darker dorsal coloration than later in the day. The cock will have the best most elevated site with the sub-males having the next best followed by the females (Harris 1964).

Food Habits

Agama agama are primarily insectivores, however A. agama have been known to eat small mammals, small reptiles, and vegetation such as flowers, grasses, and fruits. Their diet consists of mainly ants, grasshoppers, beetles, and termites (Harris 1964). A. agama is a sit and wait predator (Crews et al., 1983). Hunting by vision, it sits in vegetation, under a rock outcropping, or in the shade and waits until an insect or small mammal walks by and then will chase the prey. They catch their prey by using a tongue with a tip covered by mucous glands; this aids the lizard in holding onto small prey such as ants and termites.

Conservation Status

Contributors

Ryan Hilgris (author), Michigan State University, James Harding (editor), Michigan State University.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

desert or dunes

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.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

References

Crews, D., Gustafson, J.E., Tokarz, R.R.. 1983. Physcobiology of Parthnogenesis. Pp. 205-232 in R Huey, E Pianka, T Schoener, eds. Lizard Ecology. Studies of a Model Organism.. Cambridge, Mass. and London, England: Harvard University Press.

Harris, V. 1964. The Life of the Rainbow Lizard. London, England: Hutchinson Tropical Monographs.

Porter, W., C. Tracy. 1983. Biophysical Analysis of Energetics, Time-Space Utilization, and Distributional Limits. Pp. 55-83 in R Huey, E Pianka, T Schoener, eds. Lizard Ecology. Studies of a Model Organism.. Cambridge, Mass. and London, England: Harvard University Press.

Regal, P. 1983. The Adaptive Zone Behavior of Lizards. Pp. 105-118 in R Huey, E Pianka, T Schoener, eds. Lizard Ecology. Studies of a Model Organism. Cambridge, Mass. and London, England: Harvard University Press.

Simon, C. 1983. A Review of Lizard Chemoreception.. Pp. 119-133 in R Huey, E Pianka, T Schoener, eds. Lizard Ecology. Studies in a Model Organism.. Cambridge, Mass. and London, England: Harvard University Press.

Stamps, J. 1983. Sexual Selection, Sexual Dimorphism, and Territoriality. Pp. 169-204 in R Huey, E Pianka, T Schoener, eds. Lizard Ecology. Studies in a Model Organism.. Cambridge, Mass. and London, England: Harvard University Press.