2nd International Workshop on Conservation Biology

Is population of Moor frog (Rana arvalis) under severe decline in Mura river basin in Slovenia?

Not scheduled

UP FAMNIT, Koper, Slovenia

Speaker

Mrs Maja Cipot (Centre for Cartography of Fauna and Flora)

Description

Distribution of Rana arvalis in Slovenia is well known (Poboljšaj s sod. 2008, Stanković & Cipot 2014). Since it is a charismatic species in Slovenia, there are known many observations by enthusiast and only in few occasions data are result of systematic research. As a result population conservation status and population size and trends are in majority unknown. The only systematic survey targeted for Rana arvalis was made in 2011 on Ljubljansko Barje (Cipot 2011; Stanković & Cipot 2014) and in spring 2013 and 2014 on a large part of Mura river Basin (presented here). We performed a complete screening of Natura 2000 site Mura from Gornja Radgona to Vučja vas. An insight of population size and density in this area was obtained by egg mass counting, counting of blue adult males. Data are also available for some other major spawning sites of the species in Mura basin (from years 2013-2014, 2011 and 2008 respectively). Numbers gathered during our study were surprisingly low. There are only few known localities with high number of breeding animals in the Mura river basin: oxbows Zaton (Petanjci), Bunčani, Muriša (Lendava), Csiko Legelo (Lendava) and Nagy Parlag (Lendava), forest Polanski log (Velika Polana) and forest Črni log (Lendava). We noticed a severe decline of populations in the area in the last decade. The results of egg mass counts in Polanski log between years 2011-2014 showed that in 2014 only one tenth of numbers of 2011 were counted. A similar trend of decline is observed from 2008 to 2013 from Zaton oxbow. Exact causes for the decline are not known, but several natural and anthropogenic factors such as pollution, habitat disappearance and degradation are in place. Potential causes for the decline are the drainage of the oxbows due to lowering of the ground water level, afforestation of oxbow banks and shading of breeding sites and large forest clear cuts. Whether numbers gathered in last few years are a sign of population decline which is heading toward local extinction, we don’t know. Certainly an action is needed.