ONTOGENETIC AND SEASONAL CHANGES IN COLORATION OF THE BLUNT-NOSED LEOPARD LIZARD (GAMBELIA SILA)

Among crotaphytids, the blunt-nosed leopard lizard (Gambelia sila) is one of only 2 species known in which adults do not have permanent dichromatic patterns, but both males and females display bright breeding colors. Males in most populations develop a salmon color over most of their head and body, whereas females develop rusty red blotches laterally along the head and trunk. Also unusual is the yellow color exhibited by juveniles. Between 1992 and 1994, we captured adult and juvenile G. sila on the Elkhorn Plain, San Luis Obispo County, California, and scored individuals for their coloration. juvenile G. sila developed a yellow color on the undersides of their hind limbs and tail that was apparent when they were about 55 mm snout-vent length (SVL) and was prominent until about 85 to 90 mm SVL. Both males and females developed breeding colors between 85 and 95 mm SVL. Breeding colors of adults developed soon after they emerged each year in April or early May, and most adults retained breeding colors until they ended activity in July or August, although coloration fluctuated within a season for some individuals. Individual differences in the amount of coloration occurred with some large adults never developing fully bright breeding colors. Females produced multiple clutches in each year, and their breeding colors were not immediately apparent with their first clutch and sometimes faded, but did not disappear, between clutches.