Subspecies status of Common Eiders Somateria mollissima in Shetland based on morphology and DNA

Capsule Morphometrics, plumage and mitochondrial DNA of Common Eiders Somateria mollissima in Shetland indicate that these birds should be classified as subspecies faeroeensis. Aims To test whether molecular data support the suggestion based on measurements that Common Eiders in Shetland belong to the subspecies faeroeensis. Methods DNA extracted from Common Eiders found dead in Shetland was amplified and a section of the mitochondrial genome was sequenced to compare with data from birds previously sampled from Iceland, Faroes, east England and continental Europe. Results Shetland Common Eiders are closely similar to birds from the Faroe Islands classified as subspecies faeroeensis, and somewhat distinct from the nominate mollissima to which all Scottish eiders have been conventionally assigned. Eiders from southern Iceland have haplotypes more similar to faeroeensis despite differing in plumage and being assigned on plumage to a different subspecies borealis. Conclusion Molecular data indicate a need to revise the classification of common eider subspecies, with birds from Shetland considered as subspecies faeroeensis.