The feeding ecology of the otter on three Northumbrian watersheds

Abstract

The diet of the otter on three Northumbrian rivers was assessed using spraint analysis. A total of 167 spraints were collected between March and June 1980, 80 from the North Tyne, 32 from the Blyth, and 55 from the Wansbeck-Font. Spraints were analysed using keys, photographs and reference collections, and where possible back calculations of fish size were attempted. Results showed that fish formed the majority of the prey intake, mammal and bird occurrence were rare. The North Tyne showing the greatest variety in prey species taken. Eel were found to be the major fish prey taken on the North Tyne and Blyth, and bullhead on the Wansbeck-Font. In general, similar size prey species were taken on the three watersheds, and seasonal data suggests a reduction in crayfish, amphibia, Cyprinidae, trout, and perch in the summer compared to the
spring diet. The results show no evidence of competition for food between mink and otter on the North Tyne.