While seabird monitoring at Sumburgh Head, Shetland on 18 June 2008, I noticed a particularly bulky Northern Fulmar Fulmarus glacialis (hereafter ‘Fulmar’) on the sea, feeding on a dead Atlantic Puffin Fratercula arctica (hereafter ‘Puffin’). What caught my attention was the apparent size of the Fulmar, appearing almost twice normal! While tugging at the Puffin, it held its wings constantly half arched in a very intimidating posture, unlike anything I have seen before. The reason for this soon became evident when a nearby Great Skua Stercorarius skua flew in to try and steal the corpse, though the skua was almost certainly the original killer of the Puffin.

Cramp, S. & Simmons, K. E. L. (eds.) 1977. The Birds of the Western Palearctic. Vol. I. Oxford University Press, Oxford.

Enquist, M., Plane, E. & Röed, J. 1985. Aggressive communication in Fulmars (Fulmarus glacialis) competing for food. v Animal Behaviour 33: 1007–1020. [Crossref]