Demography and population dynamics of the lacertid lizard Podarcis bocageiin north-west Spain

The demography and life-history traits of a population of the lacertid liza rd Podarcis bocagei in north-west Spain were investigated. Most of the conc lusions presented are based on mark-recapture studies carried out over a 2- year period. Reproductive characteristics are similar to those reported for other temperate-climate lacertids. Clutch size, egg size and hatchling siz e (snout-vent length, SVL) are all positively correlated with the mother's SVL. Only large females lay more than one clutch per year. Growth rate is h ighest in young animals and declines gradually with age. In both sexes, sex ual maturity is reached between the ages of 1 and 2 years. Again in both se xes, the probability of survival was fairly constant over the lifespan. Con sidering the study period as a whole, there was no significant between-sex difference in survival probability. Among adults, the probability of surviv al was higher in winter than during other periods, but the differences were not statistically significant. The individuals of the study population are sedentary, making only short movements even when periods of up to 2 years are considered (the mean distance moved between marking and recapturing 18- 24 months later was 15.7 m, maximum 45.6 m). On average, immature individua ls move further than adults, and adult males move further than adult female s. Estimated population density (all individuals) dropped from 1574 ha(-1) during the winter of 1989/90 to 1327 ha(-1) during the winter of 1990/91. T he decline in population density over the study period was also reflected i n the estimated net replacement rate for the population (0.85, i.e. conside rably less than one), and is probably attributable to colonization of the s tudy site by plants (reducing suitability as a habitat for P. bocagei). Est imated mean generation time was 2.09 years.