Sooty Shearwater – 2006

Puffinus griseus – ADERYN –DRYCIN DU – Regular autumn passage migrant. Has not been recorded in February, June or November.

The Sooty Shearwater breeds in New Zealand and its sub Antarctic islands, south west South America, the Falkland Islands, the South Atlantic islands and Australia. They spend winter in temperate sea areas in the North Pacific and North Atlantic. In the Atlantic they travel off the eastern seaboard of the Americas to the Newfoundland area, returning south off the western seaboard of Europe.

The Sooty Shearwater was first recorded in Pembrokeshire on the 9th September 1931 when R. M. Lockley saw one from a boat between Skokholm and Grassholm. Then Lockley et al (1949) stated “Seen fairly regularly during the early part of September off Skokholm.” 

A total of 41 were recorded between 1957 and 1978, most being logged at Skokholm but some were also noted off Skomer, South Bishop, from boats visiting Grassholm and the Smalls, from the Fishguard to Rosslare ferry and off Strumble Head.

They continued to be recorded on occasions at these places and also off St David’s Head, Ramsey, St Govan’s Head, from the Pembroke to Rosslare ferry, off the Swansea to Cork ferry and from small vessels visiting the Celtic Deep area. One to five birds per day were involved apart from 20 at the Celtic Deep on the 15th September 2002. However, much larger numbers were logged with greater regularity at Strumble Head between 1980 and 2006.

Overall annual pattern 1980-2006 at Strumble Head

(Expressed as the mean number of birds per six day periods. Values were adjusted for the seven day periods at the end of Aug and Oct by dividing their totals by seven and multiplying by six before calculating the mean.)

Passage has been recorded from the 3rd July to the 19th November, peaking in August and September but some sightings have been made outside this period. They were single birds at the Smalls on 22nd March 1984, at Whitesands Bay on the 28th December 2000, at Strumble Head on the 2nd January 1988, 3rd May 1982, 23rd December 1983 and 27th December 2006.

Analysis

The number of Sooty Shearwaters seen has been dependent on the nature of the weather systems occurring during the peak passage time, August to September. A trickle of small numbers were recorded during light to moderate winds, larger numbers in more turbulent weather.

During the 1980’s Atlantic depressions moving south-west to north-east with their centres passing over Northern Ireland and Scotland were prevalent. Locally these produced south-west gales which veered north-west before moderating when the system progressed further to the north-east.

The south-west component is thought to have displaced shearwaters from the Western Approaches into the Irish Sea. They were able to make their way back southwards when the wind wore around to the north-west, many of them passing close in to the north Pembrokeshire shore in the process. The largest counts of Sooty Shearwaters at Strumble Head were made during these conditions, i.e. 237 on the 1st September 1985 and 397 on the 3rd September 1983.

The depressions that occurred in August and September between 1990 and 2006 tracked further south with their centres over Pembrokeshire or further to the south. These systems did not produce the south-west going north-west winds locally, indeed they often produced easterly winds which did not prove favourable for placing Sooty Shearwaters in Pembrokeshire waters.

They did occasionally produce strong north winds blowing through the North Channel and down the Irish Sea, which pushed some Sooty Shearwaters close to the north Pembrokeshire shores but in lesser numbers than during the 1980’s. Counts between 11 and 35 were made on peak days, the maximum being 42 on the 14th September 2004.

Breakdown of Strumble Head totals

1980 – 891736
1990 – 99645
2000 – 06474

Graham Rees (County bird recorder 1981 to 2007)

LOCKLEY. R. M, INGRAM. C. S. and SALMON. H. M.1949. The birds of Pembrokeshire, West Wales Field Society.

More about the Sooty Shearwater in Pembrokeshire