Non-intrusive monitoring of otters (Lutra lutra) using infrared technology

摘要: Remote, non-intrusive monitoring of elusive mammals remains problematic, particularly in running waters. The utility using submerged infrared counters for non-intrusively the activity Eurasian otters Lutra lutra was assessed three tributaries River Dee (Beltie, Cattie, Feardar; Scotland) during 2003–2004. Otters passing through were strongly nocturnal and displayed a bimodal diel pattern. Seasonal indices varied fourfold between peaked salmonid breeding season. median time elapsing consecutive night visits 2.02 0.79 days did not differ tributaries. head–body length adult estimated at 75.0 1.1 cm, whereas upstream swimming speed calculated 0.97 0.01 m s 1 . Minimum census estimates revealed least two adults Beltie, juveniles with one juvenile Feardar. Our study indicates that, under suitable conditions, technology can be used effectively to examine free-ranging waters, offering some advantages over previous, more intrusive techniques that relied on collection spraints, use radioisotopes or tracking marked individuals.