Investigation into the Dietary Habits of the Eurasian Otter (Lutra lutra) in the County of Essex

Monitoring throughout the county of Essex has shown annual widening of otter distribution. There is, however, room for expansion and some areas remain un-colonised. This paper reports a snapshot study of spraints collected from within the areas of known distribution, providing additional insight on a growing population. Prey remains were identified to family level and data used to calculate trophic breadths over the range of stream orders. Investigative comparisons were used to detect changes in diet with stream order. Further consideration was given to the importance of crayfish predation (e.g. the signal crayfish Pacifastacus leniusculus).Within the sample (n= 54) from four stream orders (Strahler 2-5), fish occurred most frequently (67%). Other groups included; invertebrates 20%, birds 7% and mammals 6%. Crayfish comprised 4% of the sample. There were no significant differences between Trophic Niche Breadth and stream order (H*=2.73, P>0.05), a finding strengthened by subsequent statistical analysis of the data. Dietary composition was consistent within the range and period studied. Extended research could determine seasonal variation and the extent to which available prey assemblage limits distribution against wider environmental and biological variables.