Distribution of the Colour Phases of the Fulmar (Fulmarus glacialis)

Abstract

CHARACTER gradients1 in animals are receiving so much attention that additional raw material, particularly of a quantitative kind, is urgently required. The ornithologists, who by reason of their numbers have already made a good start with the distribution of the ‘bridled’ form of the guillemot (Uria aalge)2,3, might now well extend their observations to the fulmar (Fulmarus g. glacialis). Unlike the guillemot, the fulmar does not exhibit a simple ‘dimorph-ratio cline’, but shows a polymorphic one (first discussed by Eagle Clarke4), which seems, from the limited evidence available, to be of a rather complicated nature. The accompanying distribution map, compiled from twenty-six literature sources, gives a general indication of the situation.