Sceloporus occidentalis, like most lizards, mate and then the female lays a clutch or group of eggs in a pit during the spring and summer or mating season. The mating season ranges from March to June, but more specifically the courtship and copulation take place during these months (Nafis, 2013). Goldberg’s study discovered that spermiogenesis starts in February for lowland lizards and ovulated eggs were seen in early April; however, the mountain lizards trail these dates by six weeks (Goldberg, 1974). This possibly could be because of temperature differences between the two ranges, and this shortening the breeding cycle at high elevations. These two processes are required for both male and female lizards before either one is ready to produce offspring.                

Used with permissionDuring mating, a male defends his roughly defined territory of up to twenty five feet radius (Nafis, 2013). He defends it by posturing and by physical combat with other males (Morey, 1988). The Western Fence Lizard male requires a perch site to observe mates, rival males or to display (Morey, 1988).  He will ventrally flatten his body to display the bright colors and will also perform “pushups,” or rapid up and down movements in order to attract mates or display territorial defense (Fitch, 1938).  This allows the male to show off to the females from his high perch, and to inform other males what is his. The defense of the territory becomes less and less vigorous as the summer goes on. Female Sceloporus occidentalis however, will not allow the males to mate with her until she is ready, meaning that the eggs are ovulated and she thinks the timing is right (Fitch, 1938). During copulation the male becomes brilliantly blue, blue patches appear on all of his dorsal scales (Fitch, 1938). After this the male’s job is finished and the rest is up to the female.                

Goldberg has done extensive studying on the reproduction of populations of lowland and mountain lizards, and has discovered that the Western Fence Lizard female is able to lay one to three clutches in the low lands and one to two in the mountains (Goldberg, 1974). The female lizards will mate several times over the mating season and will produce several clutches of eggs. After the female and male have mated, normally the female will lay the eggs two to four weeks after copulation (Nafis, 2013). The clutch sizes range from three to seventeen eggs, and there are slightly larger clutches laid in the mountains. The females lay their eggs in pits that they have dug in damp soil that is well aerated (Morey, 1988). They will lay clutches from May to July, because of the several mating between the males and females (Nafis, 2013). The eggs need approximately ten weeks for development of young before they start to appear in early July in the lowlands and in mid-August in the mountains. The hatchlings measure 24-26 millimeters from the snout to vent once they emerge from the pit that they were laid in. The new young Western Fence Lizard will be able to mate next spring, this completing the full cycle of reproduction.

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