The Eurasian otter (Lutra lutra) has been described as piscivorous in Romania, but our recent studies suggested that the otter may be better defined as an opportunistic predator, with its feeding behaviour being dependent on the availability of prey. Otter is recognised as one of the top predators in freshwater systems, and thus has the potential to play an important role in the functioning of these ecosystems. Between December 2012 and September 2013, the diet of the otter, was identified by collecting and examining n 56 spraints (faeces) from 36 sites (different habitats, streams and rivers), from several river catchments throughout Putna Vrancea Natural Park in the Eastern Carpathians. In most of the spraints, fish was the main prey consumed, 31%, followed closely by amphibians with 24%, insects 21%, mammals 16% and other groups in a small amount: 3% gastropoda, 3% plantae and 2% reptilia. [ABSTRACT FROM AUTHOR]