The timing and pattern of moult of flight feathers of European Storm-petrel Hydrobates pelagicus in Atlantic and Mediterranean breeding areas

Aims: We describe the pattern and timing of moult in European Storm-petrels Hydrobates pelagicus.Location: Benidorm Island (eastern Spain, Mediterranean Iberian coast) and Vizcaya (northern Spain, Atlantic Iberian coast).Methods: Birds were caught with mist-nests set in breeding colonies and the state of flight feathers was scored. Primary, secondary and tail moult scores and the degree of moult asymmetry and an index of raggedness were calculated.Results: Moult in the primaries was ascendant, whereas in the secondaries it progressed from three different loci, and was irregular in the tail. During the breeding season, the level of raggedness was higher in the primaries than in the secondaries or the tail, but primary moult was significantly more symmetrical than in any of the other feather tracts. Primary moult started on average in late June in Benidorm, and in late July in Vizcaya. Secondary and tail moult in Benidorm started on average a month after onset of primary moult.Conclusions: Average onset of primary moult differed among areas, being earlier in southern than in northern areas. These different patterns of moult among areas are probably due to differences in breeding phenology.

Beatriz Arroyo, Eduardo Minguez, Luis Palomares & Jesus Pinilla, Ardeola 51(2), 2004, 365-373