Otters at Malham Tarn by Emily Alderton

Malham Tarn is home to an array of rare and protected animals, with the arrival of the Eurasian otter (Lutra lutra), in recent years adding to the diversity of the site.  I am currently conducting a study of the seasonal diet composition of this recovering predator, which has been poorly researched in still freshwaters.  This work will provide a better understanding of how otters use more isolated waters like Malham Tarn, and what impacts their return may have on the fish, crayfish and bird populations at this site.

The diet of the otters is being assessed through analysis of their spraint (faeces), which has been collected monthly since December 2011.  Fish and amphibian bones, and bird feathers, all pass through the digestive system relatively intact, and can be identified.  The prey species appearing most frequently in the otters’ diet seem to be bullhead, followed by small trout and amphibians.  There is evidence that some birds are being taken, but this is quite uncommon and may be from scavenging.

From personal observation and sightings by visitors and staff at the field centre, it seems that only two otters are presently living and hunting on the tarn.  These otters can often be observed on still evenings, about an hour before nightfall, fishing in the shallow waters between the bird hide and the inflow stream.