Red-throated Diver - 1994

Winter visitor and passage migrant. Recorded in every month except June

Mathew (1894) classified the Red-throated Diver as "the commonest of the three divers that visit our bays and estuaries", and noted Fishguard Harbour and Milford Haven as being particularly good localities. Lockley et al. (1949) also considered it a common visitor, especially to Milford Haven but also "frequent at sea near coasts and islands". Lockley (1961) stated that the Red-throated Diver was more frequently seen than other species of diver. The diaries of Bertram Lloyd for 1925-1937 enable us to compare the statements above with the current situation and his record is consistent with modern findings, so it is probable that the status of the Red-throated Diver has not changed for at least the last 60 years or so. It remains the commonest of the diver species occurring in Pembrokeshire, but is no longer frequent in the Cleddau Estuary (the Milford Haven of Mathew and Lockley et al.) where now only one or two appear, sporadically and mostly at the seaward end.

Red-throated Divers can be found all around the outer coastline in winter. Usually only one to three birds are seen at each locality but they occasionally congregate at favoured tide-races or bays, especially following onshore gales, when up to 18 have been seen off Giltar, 20 in St Bride's Bay, 23 in the Amroth—Saundersfoot area and 40 off Strumble Head. However an exceptional gathering of 200 was at Amroth in late February and early March 1993. Singles at Llysyfran reservoir and Bicton and Hayston Hall farm irrigation reservoirs are the only records from inland waters.

There is a small northerly passage from March to May, when many are in transitional, occasionally in full, summer plumage. The autumn passage south, from September to December (exceptionally from July and August) is of greater volume. Birds in full summer plumage predominate until mid-October, indicating that most juveniles arrive later, though an adult was seen feeding two accompanying juveniles at the Gann on 27 September 1969.

White-billed Diver - 1999

Gavia adamsii

Vagrant

Breeding range is in high latitudes of the old USSR and parts of North America but distribution is not fully known. In the western Palearctic they winter along the coast of Norway with infrequent occurrences further south.

An adult was seen passing Strumble Head on the 27th September 1999.

Five observers were assembled in “The Lookout” building logging passing birds, mostly seabirds. The observers were:  Cliff Benson, Jack Donovan, Graham Rees, Andrew Sinclair and Ray Wilkinson. All were seated and equipped with binoculars and tripod mounted telescopes. They were sheltered from a force six south west wind, the sky was overcast but visibility was good.

As well as a variety of other birds, four separate Red-throated Divers had passed close inshore when Ray “called” another diver approaching, following the same line of flight. This one was larger with a slower wing beat than the Red-throated’s and when it came level with the observation point exhibited a large slightly yellow white bill which appeared curved upwards. All other visible features were noted and some sketches made, enabling a positive identification as a White – billed Diver and the assessment that it was an adult in transition between summer and winter plumage.

The record was duly accepted by the BBRC and to date remains the sole recorded occurrence for Pembrokeshire and the second for Wales.

Graham Rees

(Covers records up to and including 2008)

Great Northern Diver - ages

Gavia immer

Observers have seldom included an age assessment in their reports unless noting adults in summer plumage.  

Great Northern Divers have a prolonged post breeding moult period stretching from September to January, consequently birds in summer plumage have been recorded throughout autumn passage, occasionally as late as the end of December. Of a total of 646 birds closely scrutinised passing Strumble Head in autumn, between 1981 and 2008, 48% were in full or showed variable vestiges of summer plumage.

A few birds have been recorded in full summer plumage in the spring, from late April.

Graham Rees

(Covers records up to and including 2008)

Great Northern Diver - spring passage

Gavia immer

Spring passage has been relatively small, mostly recorded as departure dates from wintering areas, normally completed by late March to early April. Occasionally presumed migrants have briefly appeared at some of these same places in late April up to 22nd May and others have been noted at or passing headlands and the offshore islands from late March to 26th May. Later occurrences were: one in the Gann – Lindsway Bay region throughout May until at least the 21st June 1991 and two at Ceibwr on 22nd June 1997. 

Great Northern Diver - autumn passage

Gavia immer

The variation in county annual totals seems to have had more to do with variation in the number of passage migrants recorded than with the number of wintering birds. Autumn passage has been noted along the coast and at the offshore islands, being most consistently documented at Strumble Head annually between 1983 and 2006.

The earliest recorded there was on 28th July 1991. August records were all of single birds, on the 31st in 1985, 24th in 1986, 28th in 1989, 23rd in 1994, 28th in 1994 and 27th in 1995. Numbers built up in September, the main passage taking place from October to December:

Totals have been grouped into six day periods, except that the last readings for October and December have been adjusted from seven day totals. This has been done by dividing the seven day totals by seven, then multiplying by six.

Great Northern Diver - winter

Gavia immer

In winter they have been found in the offshore waters all around the coast from Cemaes Head to Amroth, including Fishguard harbour.

Most sightings have been of single birds or sometimes two together, with occasionally up to seven in areas such as St Bride’s bay, Fishguard Harbour and the Strumble Head tide races. The unusual gathering of 43 at Strumble Head on 6th January 1991 was probably due to birds seeking a lee shore during a period of prolonged SW gales.

Great Northern Divers have regularly been seen within the Milford Haven / Cleddau Estuary waterway during the winter months, January to April and October to December. The average number recorded between the years 1983 and 2003 was five, the maxima in a year being 10 in 2002 and 12 in 1999, which probably included some migrants in transit.

Most records were from the area between Dale and Hakin, including the Gann, Angle Bay and the Pembroke River. Singles have been seen further upstream at Castle Pill, Llanstadwell, Neyland, Lawrenny, Cresswell and Carew Rivers, including the tidal Carew Mill Pond, Garron Pill, Beggars’s Reach,  Llangwm and Landshipping to Hook Reach area.

The only fresh water occurrences on record are of one at Bosherston 9th – 13th November 1986, two at Llys y fran Reservoir 16th January 1986, with singles there in 1983, 1984, 1985, 1999, 2001, 2002 and 2006.

Great Northern Diver - status

 Gavia immer

Winter visitor and passage migrant.

The Great Northern Diver breeds across the sub Arctic region of the Americas, Greenland and Iceland and on rare occasions has bred in Scotland and as far east as Svalbard.  Those that winter in the east Atlantic do so as far south as the Bay of Biscay and Iberia.

As with many other species, it is difficult to assess the Great Northern’s status in Pembrokeshire in the past. The accounts of previous authorities have been largely anecdotal and prone to expressions like “sometimes numerous” and “frequently seen”.

Dickenson and Howells (1962) must have felt sufficiently able to interpret the past to state “From the numbers recorded in the last decade it is possible that a decrease has taken place since the 1930’s.” The decade they referred to was 1952 to 1961, when an average of three per annum was recorded, the maximum in any year being nine in 1959.

The average recorded per annum remained at three until 1982, the maximum in a year being six in 1972. By 1983 an increasing number of observers were putting the results of their observations into the communal record and from then until 2006 the average number recorded reached 61 per annum, with the most in a year being 119 in 1999:

There was a marked increase in the number of active observers during the 1980’s and 1990’s, they possessed ever improving optical aids and most had the discipline to contribute their observations to the communal record. These are likely to be the factors that explain the upsurge in records, rather than there being an increase in the number of Great Northern Divers visiting Pembrokeshire.

References

DICKENSON. H and HOWELLS. R. J. 1962. Divers in Wales, Nature in Wales 8.

DONOVAN. J and REES. G. 1994. Birds of Pembrokeshire, Dyfed Wildlife Trust.

LLOYD. B. 1929-1939 Diaries, National Museum of Wales.

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

MATHEW. M. 1894. The birds of Pembrokeshire and its islands, R. H. Porter.

Black-throated Diver - passage

Gavia arctica

Donovan and Rees (1994) pointed out that the Black-throated Diver was a passage migrant as well as a winter visitor to Pembrokeshire. Passage has involved occasional birds flying southwards along the coastline and passing the offshore islands, mostly between September and December, although singles were recorded passing Strumble Head on 20th August 1997 and 21st August 1999 and one was at Lydstep Haven on 30th August 1988.

The number of migrants recorded has been small, with an average of nine per annum between 1983 and 2003, the most in any year being 29 in 1999. Passage has been well documented at Strumble Head, where the total between the years 1983 and 2006 is tabulated by month :

Sep - 8

Oct - 45

Nov - 85

Dec - 31

Most Black–throated Divers have departed the county by the end of March but there are 11 April records and four for May, the latest being one at Broad Haven (North) on the 25th in 1961, perhaps indicating birds passing through.

The Black–throated Diver has not been recorded in Pembrokeshire in June and July.

Graham Rees

(Covers records up to and including those for 2006)

Black-throated Diver - Winter

Gavia arctica

Winter visitor and passage migrant

The Black –throated Diver has an Arctic breeding distribution, stretching from Siberia to Iceland extending as far south as Scotland. Those occurring on the eastern side of the Atlantic migrate to winter as far south as the Bay of Biscay and north-west Spain. Gavia arctica pacifica from North America and N E Siberia is currently considered as a separate species.

Previous commentators have assessed the Black – throated Diver in Pembrokeshire as a scarce winter visitor. 

In winter they have been recorded in offshore waters all around the outer coast, once as far out as The Smalls, on 22nd January 1982. Because they can be difficult to detect and identify in the often choppy sea, they may be under recorded. Donovan and Rees (1994) suggested that perhaps a dozen were spread around the coastline each winter. The records for 1983 – 2003 show an average of six to seven detected each year, however nine were noted in four different years and 10 in 1997.

They have been noted within the Milford Haven / Cleddau Estuary waterway 14 times in eight different years, all single birds apart from two at Neyland on 28th December 1963.

Most were noted around Dale and the Gann but also once each at Angle Bay and Pembroke Dock, as far up the estuary as Landshipping on 31st December 1963 and at Lawrenny on 1st January 1997 which had reached Landshipping by February.

One which collided with the Cleddau Bridge during a storm in the late winter of 1996, was rescued by the Texaco Bird Hospital, rehabilitated and released at Lawrenny just before the end of the year. This bird probably accounts for the records at Lawrenny and Landshipping in January and February 1997 noted above.

The only record away from salt water was of two at Llys y fran Reservoir on 22nd February 1986.

An oiled bird was on the Teifi at Cilgerran on 19th & 20th March 1995 and two oiled birds were recovered during the Sea Empress oil spill of 1996.

Total birds on record : 1982 – 2006

References

DICKENSON. H and HOWELLS. R. J. 1962. Divers in Wales, Nature in Wales 8.

DONOVAN. J and REES. G. 1994. Birds of Pembrokeshire, Dyfed Wildlife Trust.

LLOYD. B. 1929-1939 Diaries, National Museum of Wales.

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

MATHEW. M. 1894. The birds of Pembrokeshire and its islands, R. H. Porter.

Great Northern Diver - 1894

Species account from M Mathew, 1894, The Birds of Pembrokeshire and its islands

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Black-throated Diver - 1894

Species account from M Mathew, 1894, The Birds of Pembrokeshire and its islands

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Red-throated Diver - 2005 status

Gavia stellata

Winter visitor and passage migrant.

The Red–throated Diver has a circumpolar Arctic breeding distribution, the nearest nesting to Pembrokeshire being in Scotland. Those on the eastern side of the Atlantic winter southwards to the Bay of Biscay, sometimes entering the Mediterranean.

Mathew (1894) and Lockley et al (1949) considered the Red-throated Diver to be a common winter visitor. The former gave no actual counts and the latter noted only a group of 20 off the west coast and 15 off Giltar Point.

Bertram Lloyd (1939) recorded all the Red–throated Divers seen during his intermittent visits to the county during the period 1929 – 37.  The places he saw them coincided with localities where they were noted in the 1980’s and 1990’s, as did the numbers involved. This led Donovan and Rees (1994) to think that perhaps this diver’s status had not changed in the previous 60 years or so.

Dickenson and Howells (1962) commented that almost every winter small numbers of Red–throated Divers had been seen off both the west and south coasts of Pembrokeshire, from mid October to the end of April. That they had been recorded within Milford Haven and Fishguard Harbour and that R. M. Lockley had told them that he recorded them frequently on his winter journeys from Skokholm to the mainland between 1927 and 1940. They went on to note that from the numbers recorded in the last decade it is possible that a decrease had taken place since the 1930’s.

The average number recorded in the 1930’s was 10 per annum which included 43 noted in 1930. The average recorded from 1952 to 1961, the period covered by the Dickenson and Howells review, was only 5 per annum, the most in any year being 10 in 1961.

The average on record for the years 1963 to 1982 was 6 per annum, the maximum in any year being 23 in 1973. How much credence can be put into these statistics being representative of the true picture is brought into question, when considering that in the period 1983 to 2002 an average of 225 per annum were put on record, the largest total in a year being 394 in 2001.

There was a marked increase in the number of active observers during the 1980’s and 1990’s, they possessed ever improving optical aids and most had the discipline to contribute their observations to the communal record. These are likely to be the factors that explain the upsurge in records, rather than there being an increase in the number of Red–throated Divers visiting Pembrokeshire.

TOTALS RECORDED 1983 – 2005

These totals have been calculated by summing the maximum for each locality in each season and the number seen visibly migrating. They do not attempt to assess any possible turnover in numbers at specific sites and the migrant totals would have been influenced by the amount of time spent watching from headlands and islands. It is likely therefore that the totals represent the minimum presence in local waters.

References

DICKENSON. H and HOWELLS. R. J. 1962. Divers in Wales, Nature in Wales 8.

DONOVAN. J and REES. G. 1994. Birds of Pembrokeshire, Dyfed Wildlife Trust.

LLOYD. B. 1929-1939 Diaries, National Museum of Wales.

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

MATHEW. M. 1894. The birds of Pembrokeshire and its islands, R. H. Porter