Dynamics of Lacerta saxicola population (Reptilia, Sauria) spatial structure in broad-leaved forests of the Navagir Ridge

摘要

The lizard Lacerta saxicola inhabits all oak forests on valley slopes in the investigated area. It occurs permanently in beam-beech forests on valley bottoms only in gaps forming as a result of falling trees. The lizard population in the gaps amounted to about 8 percent of the total one in the forests. The population density in gaps is several times as high as on slopes. The gap populations are stable closed settlements of territorial adults. The juveniles are forced out of the gaps to valley slopes. The abundance of food and shelters pn valley bottoms is much higher than on its slopes. In forests, the conditions for lizards are unfavorable due to lower temperature. They can bask only in gaps. The lizards from slopes visit periodically valley bottoms, but in gaps they do not leave their settlements. In hot periods lizards migrate from slopes to valley bottoms. This situation is repeated every year, In the period of mass miggration in gaps lizard populations remain closed and permanent by their composition. Settled males from gaps mate with local settled females as well as with those from slopes coming to gaps. Males from slopes have then opportunity to mate only with females from the same biotope.