Nest-site fidelity of the European pond turtle Emys orbicularis (LINNAEUS, 1758) (Testudines: Emydidae) in western Poland

摘要

59 nests of the European pond turtle Emys orbicularis (L.) were marked in the valley of the Ilanka river (Ziemia Lubuska, western Poland) in the years 1999-2006. 54 nests built by 16 marked females were located in a relatively small area. The remainsof 5 other nests, belonging to unknown females and damaged by predators were found in 3 localities in the vicinity of the main study area. 3 out of all marked females laid eggs once, the remaining 13 females 2-7 times. Cases when females laid eggs at least two times were taken into account i.e. 51 nests. Females laid eggs on steep, sunny mid-forest clearings with areas of 375 m~2- 1170 m~2 and situated at a distance of 69-83 m (aver. 77 m) from water bodies. Apart from the nesting grounds studied, 5 disturbed nests mentioned above were located at a distance of 150-270 m from water bodies. The distance between nests was 0.75-53.9 m (aver. 8.8 m). Most females consistently, each year opted for the same nesting sites (nests) as previous years. Successional vegetation growth and overshadowing of the clearings led to the use of locations in nearby areas. Once overshadowing was eliminated, females returned to locations in which they had been observed previously.