The diet of otters (Lutra lutra L.) in Danish freshwater habitats: comparisons of prey fish populations

摘要: Otter spraints from five Danish freshwater localities were analysed. In all fish was the main prey (76–99% of estimated bulk), especially in winter. Depending on locality, mainly consisted cyprinids (Cyprinidae), percids (Percidae) or salmonids (Salmonidae). Seasonal variations found diet corresponding to availability prey. Non-fish categories, such as frogs, birds, mammals and invertebrates, most frequently taken spring summer, but only frogs made an important contribution (0–21%). The results analysing 978 otter compared with populations by electrofishing. It concluded that species composition generally reflected foraging area, however, exception a negative preference for trout (Salmo sp.) sticklebacks (Gasterosteidae) some study areas. Otters took available sizes tendency selecting individuals between 9–21 cm, though preferred size eels 18–36 cm. A principal component analysis showed variation associated differences communities free-flowing rivers lake outflows.