Puffinus mauretanicus – Aderyn-Drycin Môr y Canoldir – Regular visitor. Not recorded in February and March
This bird was not recorded by Mathew (1894) or Lockley et al. (1949), but one was collected in Pembrokeshire in September 1900 and is in a museum at Harvard, USA (per W.R.P. Bourne). It was next noted at the Smalls in July 1955, and in the 1960s and 1970s it became apparent that the species was a regular visitor in small numbers, up to five at a time, during the months July to October. Most observations came from Skokholm where the principal watching effort was concentrated at the time.
Regular and frequent watching from Strumble Head during the 1980s has shown that the Mediterranean Shearwater occurs in greater numbers than was previously thought, with a daily maximum of 26 on 8 October 1987, and that they appear as early as late June (with one record in April and in May) and a few stay on into the following January. These late birds are only seen inshore during onshore gales suggesting that in calmer weather they would be feeding out of sight of land. Some confirmation of this was obtained when regular observations at the Smalls in 1983 and 1984 provided December and January sightings.