Partial Albinism in Manx Shearwater

On 13th August 2008, I was observing a good movement of seabirds past Pendeen Watch, Cornwall. The wind was force 6+ west with occasional rain showers and mainly dark cloud covered skies. The majority of Manx Shearwaters Puffinus puffinus were passing along a similar line relatively close inshore. Due to the overcast skies, light conditions and sea colour were both conducive to studying the finer points of their plumage. Therefore a bird which passed at c11.30 showing a fairly large pure white patch in the centre of it’s right wing, almost reminiscent of Black Guillemot Cepphus grylle, was immediately obvious. Due to the bird only being observed for little over a minute, it is not clear exactly which feather tracts, or how many feathers were white. The white feathers appeared to mainly include greater coverts, although it may have included some secondaries. The lack of reports of partial albinistic Manx Shearwaters suggests such cases are rare, but it has been recorded on previous occasions in Manx Shearwater (Brit. Birds 83: 22-23) and in Balearic Shearwater Puffinus mauretanicus (Brit. Birds 83: 22; Brit. Birds 81: 235-236).