Bunch grass lizard, Sceloporus scalaris, population dynamics at La Michilia Biosphere Reserve, Mexico

We studied the population dynamics of Sceloporus scalaris from 1979 to 1982 using mark-recapture methods. The estimated population density was 50 adul ts per hectare. The sex ratio was approximately 1:1, with females slightly predominating at older ages. Based on morphological data, four well-differe ntiated age classes were established - juveniles, sub-adults, adults <1 yr and adults >1 yr. The mean clutch size was 8.8 eggs per female, but varied widely (5 to 12) in relation to female body size. The estimated number of h atchlings in 10 hectares was 2245 and embryo mortality was 13.89%. After ha tching, the average mortality was higher than 76% for all ages and both sex es. The population life table indicates a Slobodkin Type IV survivorship cu rve, with a net reproductive rate of 1.059. The average generation time for this population was 1.2 years.