Abstract

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.

In: Amphibia-Reptilia

Abstract

During a field study in 1983-1984 in a 200 km 2 study area in the south of Evros province (Greece) the presence of 11 lizard species was established. For every species a distribution map within the area is supplied. In different parts of the area thc lizards formed different species combinations. Ophisops elegans appeared to vicariate in certain terrains with both Podarcis erhardii and P. taurica. By studying habitat selection and activity patterns of all species data on spatial and temporal niche segregation could be obtained. The activity patterns of all species were strongly influenced by exposition and altitude. In some species a strong altitude influence was also measured on growth and some other life history data. Some pairs of morphologically or ecologically related species are compared in more detail. Some species occurred in very high densities (Lacerta viridis up to 500, Ablepharus kitaibelii up to 1100 ind./ha). Tail loss frequencies of all species are given. For many birds of prey they formed an essential food source.

In: Amphibia-Reptilia

Abstract

Inundation effects on terrestrially hibernating Bufo bufo and B. calamita are reported. Mortality caused by experimental inundation of seminatural hibernation sites was high in B. calamita and very low in B. bufo. In a floodplain eight telemetrically monitored B. bufo withstood flooding during a period of 25-35 days without leaving their hibernation sites. After this period the emerging toads suffered mortality by floating down the river depending on the water level at the moment of emerging. The importance of floodsafe areas in floodplains is demonstrated.

In: Amphibia-Reptilia

Abstract

In the spring of 1984 an ecological investigation on the endemic salamanders Hydromantes genei flavus and Euproctus platycefihalus was carried out in eastern Sardinia. The investigation was focussed on natural population sizes and densities. The Sardinian cave salamander was found to occur in two clearly distinct habitats, viz. humid holm oak forests and limestone caves. The density found in the forests was 300/ha and 98 ± 7 individuals were found in one cave. The Sardinian brook salamander was found in a habitat not reported before, viz. a stagnant mountain lake. There the animals were rather robust, and a neotenic specimen was captured.

In: Amphibia-Reptilia

Abstract

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.

In: Amphibia-Reptilia

Abstract

In a one year study we collected ecological data of the northernmost population of P. muralis in Maastricht (50° 51' N. Lat. in the Netherlands). This population consisted of about 100 adult lizards. It was probably definitely divided in two subpopulations situated close to each other which were subdivided into 5 and 2 colonies respectively, between which there was no or hardly any exchange. Sex ratio did not significantly differ from 1.0. Compared with the wall lizards of more southern populations they were found to be rather small and to grow more slowly. The age structure of the population was out of balance on account of the small numbers of some younger year classes. Only good, i.e. warmer years are likely to enable a reasonable reproduction success. The total period of activity does not differ from that in more southern regions but the reproduction period is clearly retarded and the incubation period of eggs is distinctly longer. The frequent partial reproduction failure is probably compensated by a rather high longevity, which, however, renders the population very sensitive to each factor that increases mortality. The animals have home ranges of 15-25 m2 (no significant differences between sexes) and they have a considerable home range overlap. These home range sizes do not differ from those in more southern regions but the overlaps are much more frequent and therefore it can be concluded that there is a strong concentration on ecologically suitable and spatially very restricted spots. From a list of prey species based on faeces analysis P. muralis appears to be a non-selective feeder. On two adult specimens we found the acarine ectoparasite Ophionyssus lacertinus.

In: Amphibia-Reptilia