Distribution and population size of the European pond turtle Emys orbicularis in Ljubljansko barje, Slovenia

The exact understanding of distribution and natural history is the necessary prerequisite for conservation of the endangered European pond turtle. In this study we examined the distribution and population size of pond turtles in Ljubljansko barje, a bog of European importance (Natura 2000 site, intended to be included into the Convention on Wetlands, the 'Ramsar list'). For doing so, we used different capture and observation methods. Four hundred kilometres of drainage ditches were investigated by foot, fish traps were set at 507 localities, and 171 pond turtles were captured and measured. We conclude that pond turtles are distributed all over Ljubljansko barje, but concentrated in just 18 km(2) (areas of Gmajnice and Draga pri Igu) out of the 170 km(2) total size of Ljubljansko barje. In these two areas reproduction was confirmed. The relative density for Gmajnice was calculated to 16 turtles per square kilometre, which is lower than in Draga pri Igu, with a minimum of 57 turtles per square kilometre. The main threats for the survival of pond turtles are habitat loss, nest destruction by agriculture, an increase of floods during the past 100 years, inappropriate cleaning out of drainage ditches, and the presence of invasive non-native turtles. To make conservation efforts for the European pond turtle more effective in Ljubljansko barje, we recommend using wire meshes for protecting nests and shifting the cleaning out of ditches to the active period of pond turtles.