No abstract

1983. The lizards Lacerta agilis and L. vivipara as hosts to larvae and nymphs of the tick Ixodes ricinus. -Holarct. Ecol. 6: 32^0.In this paper we provide quantitative information on the occurrence of larvae and nymphs of the tick Ixodes ricinus in populations of the lizards Lacerta agilis and /.. vivipara. Levels of infestation were rather low, at least when compared with those of small mammals and sheep. Hence we suppose that lizards feed only a minor fraction of the total tick population. Differences in tick loads among lizard subpopulations are probably attributable to difference in body size and mobility among the host groups. Ticks exhibit a markedly clumped distribution on the lizards. This distribution pattern fits with the negative binomial distribution. The overdispersed distribution of tick larvae in the field and aspects of the lizards' behaviour are considered as factors which contribute to the observed infestation patterns.Tick larvae were active throughout summer, with peak levels occurring during June-July. Nymphs were most numerous during May-June but almost absent during the summer months. Almost always ticks were attached near the lizards' forelimbs. Possible mortality resulting from tick infestation does not contribute significantly to the overall lizard mortality. Hence, these ectoparasites seem to have but a minor impact on the lizard populations.

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.

This article shows what method is suitable for an accurate determination of the annual rhythmics of lizard species. Such a determination can be reached with the help of, amongst others, mating scars, presence of deep skin folds and the structure of the navel scars in juveniles. This method was applied in a five year intensive poulation study on Lacerta vivipara and Lacerta agilis agilis in the south-east of the Netherlands. The data on rhythmics obtained thus are discussed.

Displacements over distances of 70-150 m were carried out with 48 L. agilis and 34 L. vivipara in order to determine their ability to return to their original home range. Return rates for 70 m displacements averaged 81.5 % for L. agilis and 50 % for L. vivipara; for 100 m displacements these figures were 66.7 % and 28.6 % respectively; 150 m displacements never resulted in homing. Most returns occurred within a few days. Probably both species are familiar with a far greater area than is suggested by their home range size.