Otter monitoring between 2000 and 2004 in the Drava region (Hungary)

Abstract

The monitoring of the strictly protected Eurasian otter (Lutra lutra) started during the winter of 2000, in the Danube-Drava National Park, along the Drava River (between Őrtilos and Bares). The relative density of otters was surveyed by spraint counts along a standard route (line transect survey). The highest otter spraint density was measured at Bélavár (on Drava and backwater), and relatively high values were also found on ponds where the human disturbance was low. On the Dráva River, the mean relative density was moderate, which may be associated with the high fluctuations of water levels and the steep riverside. Otter density was lower on gravel-pit lakes and backwaters with intensive angling, as well as on watercourses and streams in connection with the Dráva River. From 2002 the monitoring was completed by genetic analysis (using nine DNA markers) from freshly collected spraints. The results of the diet composition examined by spraint analysis are also summarized. It can be concluded on the basis of the above findings that the otters' population sensitively reflects the changes of the habitats, preservation of the riverside vegetation and that of the landscape.