Comparative demography of sympatric populations of Lacerta vivipara and Lacerta agilis.

A mark-recapture study was carried out in sympatric populations of Lacerta agilis and Lacerta vivipara in the Netherlands from 1976 to 1982. In most years the age structure of both populations was pyramidal. For both species life expectation of females was higher and on average they did live longer. Hence the sex ratio for adults deviated significantly from 1.0 in favour of females. Maximum age for Lacerta vivipara was 8 years (female) and for Lacerta agilis 12 years (male). The density of both species fluctuated around 100/ha. The biomass of Lacerta agilis was twice that of Lacerta vivipara. In Lacerta vivipara the 3rd and 4th calendar year class supplied 78% of total net reproduction; in Lacerta agilis the 4th, 5th, and 6th calendar year classes supplied 68%. In both populations the population replacement rate was 2. Population turnover time was 4.83 years for Lacerta agilis and 2.81 for Lacerta vivipara. The life history strategy of the Lacerta vivipara population is compared with six other European Lacertavivipara populations.