Presumed or confirmed Common Eider Somateria mollissima x Mallard Anas platyrhynchos hybrids have been observed on a number of occasions, including in Scotland, Iceland, Denmark, North America and, most recently, Italy (Zenatello et al. 2023). A male presumed Common Eider x Mallard hybrid was found with Common Eiders in the harbour at Seahouses, Northumberland, in May 2023 (plates 256–258). It had a number of similar plumage traits to the bird shown in Zenatello et al. (2023), though the head patterning was subtly different, with, for example, the Northumberland bird having an entirely dark chin and throat.