Cormorant – 2015 WeBS

Phalococorax carbo – MULFRANBreeding resident

Maximum winter counts from all sites counted for the Wetland Bird Survey in Pembrokeshire.  Data after 2000 includes the Teifi Estuary.

Main wintering sites for this species are the Cleddau Estuary, Bosherston Lakes, and Llys-y-fran Reservoir. However, large numbers can occur elsewhere, for example 50-60 in Fishguard Harbour in early 2015.

Annie Haycock, Pembrokeshire WeBS coordinator

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Cormorant – 2003-07 breeding

Phalocrocorax carbo – MULFRANBreeding resident

Comparison with previous atlas:

1984-882003-07
Breeding confirmed1313
Breeding probable12
Breeding possibleexcluded from totalexcluded from total
No of tetrads occupied14 (of 478)15 (of 490)
Percentage of tetrads2.9%3.1%

The largest colony of Cormorants is on St Margaret’s Island and this is one of the best studied in the UK, with almost continuous census data for 50 years and over 5,000 chicks ringed since the mid 1960’s.  There are  smaller colonies on Thorne Island (it relocated from Sheep Island in the early 1990’s), on the Mew Stone, Skomer, at times on Stack Rocks off Little Haven, on the Green Scar at Solva, around Dinas Island and at Cemaes Head.  Occasionally pairs might nest at scattered mainland sites.  There are many coastal drying out sites (including jetties etc in the Milford Haven Waterway) where sometimes good numbers of birds can be seen.

The Cormorant population fluctuates from year to year, as probably in poor springs some birds fail to breed. Overall counts show there was a tendency to a decrease during the 1990’s but a modest increase again in the early 2000’s.  The total population in the county in 1984-88 survey was around 300 pairs and a census following the Sea Empress oil spill (1996) found 360 pairs, with 180 of these on St Margaret’s Island.  The population during the most recent years appears to have been stable and may have increased slightly.

The highest county population was almost certainly in the early 1970’s, when around 450 – 500 pairs probably bred, 330 of them on St Margaret’s, but the reasons for the subsequent decrease are poorly understood.  Breeding success varies from year to year but there are few years of substantial failure. Ringing has shown that considerable numbers are shot on rivers or killed in coastal fishing nets during the winter period. It seems likely that this is a major cause of population changes.

Steve Sutcliffe

More about the Cormorant in Pembrokeshire

Cormorant – 1994

Phalocrocorax carbo – MULFRANBreeding resident

Map produced by the West Wales Biodiversity Information Centre
1984-88
Breeding confirmed13
Breeding probable1
Breeding possibleexcluded from total
No of tetrads occupied14 (of 478)
Percentage of tetrads2.9%

Mathew (1894) noted Cormorant colonies at Ramsey, Skomer, Lydstep Head and Pointz Castle, Lockley et al. (1949) adding St Margaret’s Island, St Bride’s Stacks, Pwll Deri and Newport Head.

In 1969, during Operation Seafarer, 378-388 pairs were found breeding, while the Seabird Register of 1985-1987 found 362 pairs, so the population has remained fairly stable despite variation in the sizes of individual colonies. Cormorants are seen throughout the year with the colonies usually occupied from February to September, ranging from single pairs breeding on cliff sites to the largest colony in Wales at St Margaret’s Island, which held 322 nests in 1973, but 230 pairs in most years since. Mathew (1894) recorded nesting in trees at Slebech.

Ringing at St Margaret’s Island has shown that some birds remain in Pembrokeshire waters through­out the year but others, mainly immatures, move up the Bristol Channel during the winter, or along the length of the English Channel and into the Bay of Biscay as far as the Iberian peninsula. Some pass inland to the Thames Valley, a few reach Ireland and North Wales and one has been recovered in Holland. Additionally, each autumn strings of up to 20 birds are seen passing down through the southern Irish Sea and St George’s Channel from the north, and Irish‑bred birds have been noted at St Margaret’s Island.

Cormorants fish extensively in the shallow bays around the Pembrokeshire coast, penetrate all the estuaries and rivers and regularly frequent the larger inland waters such as Llysyfran reservoir, besides visiting quite small pools on an opportunistic basis. Winter roosts of up to 47 birds include several breeding sites but they also roost elsewhere, notably in trees at Llysyfran reservoir, Slebech and Fernhill.

Donovan J.W. & Rees G.H, 1994, Birds of Pembrokeshire

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Cormorant – 1980s winter

Phalococorax carbo – MULFRANBreeding resident

The BTO winter atlas showed that Cormorants were present in most coastal and estuarine 10km squares and on some inland waters during the winters of 1981-82, 1982-82 and 1983-84.

The darker the colour, the higher the relative total count for each 10km square.  The darkest blue represents over 25 birds.

Data collected by volunteers for the BTO. Lack, P. 1986 Atlas of wintering birds in Britain and Ireland. T & A.D. Poyser.

More about the Cormorant in Pembrokeshire

Cormorant – 1949

Phalacrocorax carbo carbo

Common resident.  Found on inland waters, autumn to spring.  Mathew gives the following breeding stations: Ramsey, Skomer, Lydstep Head (20-30 pairs), at Pointz Castle (where they drove out Herons), and in trees at Slebech. 

These still exist but the colonies fluctuate (eg the colony on the Mewstone, Skomer was apparently deserted in 1898 and in 1947).  Other colonies: St Margaret’s Island, St Bride’s Stacks, Pwll Deri and Newport Head.

R.M.Lockley, G.C.S.Ingram, H.M.Salmon, 1949, The Birds of Pembrokeshire, The West Wales Field Society

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Cormorant – 1894

Phalacrocorax carbo – A common resident.

There are nesting stations at various places on the coast, on Ramsey and Skomer Islands, &c. There are some twenty to thirty pair of Cormorants about Lydstep Head, near Tenby, as Mr. C. Jefferys informs us; a colony nests on trees at Slebech ; and some Herons that nested at Poyntz Castle on St. Bride’s Bay, were driven from their nests upon the cliffs by Cormorants, who took possession of them for themselves. The nesting places of the Cormorants emit an abominable stench from putrid fish remains, and are not delightful to linger near.

In the summer-time, when the streams are low and clear, numerous Cormorants come inland, and work great havoc among the trout; and we always regarded it as an evil omen when we saw one or two of them heading up our valley. It is almost impossible to approach these poachers, as there is generally a sentinel perched on some tree by the river-side, while one or two others are working the adjoining pools. When fishing we would occasionally come upon a Cormorant so gorged with trout as to be unable to fly. One day we ran back for a gun to do execution on the caitiff, but just as we were approaching within range he uttered an unearthly cry, and vomiting his spoils, made off heavily on wing.

Cormorants are often entangled and caught in fishing nets, and the birds of the year, with their white breasts, are considered by the fishermen to belong to another species, and have been sent to us as great rarities. A Cormorant, a short time since, was picked up dead, near Tenby, with an oyster clinging to and closing its mandibles. The bird was stuffed with the oyster, and is now at Bath. We have received the following particulars of this strange occurrence from Mr. C. Jefferys, of Tenby : — 

CORMORANT CAUGHT BY AN OYSTER.  “On August 22nd, 1892, the sea being somewhat rough for that time of year, the man in charge of the bathing-machines on the North Sands, Tenby, saw some 300 to 400 yards from shore, something dark which kept appearing and disappearing between the waves. Being unable to make out what it really was, and at first thinking it might be one of the bathers in danger, he took a boat and went out. Before reaching the object he saw it was a large bird, that appeared to be using every effort to rise from the water, and yet was unable to do so, its head being held down by some unseen weight. With a little trouble he secured the bird, and brought it to shore alive. It proved to be an adult Cormorant, weighing between 7 1/2 and 7 3/4 lbs., and attached to its lower mandible was a large oyster; which was afterwards found to weigh between 9 and 10 oz.

When the bird was brought me it was dead, but the oyster was still attached. It held to about an inch of the lower mandible, which in the bird’s fearful struggles to get free had broken off short, the only attachment between it and the bird being the skin of the throat, which had twisted up like a piece of catgut. The Cormorant, when diving for food, must have seized the open oyster, which closed on the bill. The bird was buoyant enough to bring the oyster to the surface, but was unable to rise from the water, and must eventually have been drowned, as it could with difficulty keep its head above the surface. Mr. A. K. Cunninghame, of Bath, who was on the shore at the time, purchased the bird from the man who obtained it, and brought it to me to set up.”

Mathew M.A. 1894, Birds of Pembrokeshire and its Islands

More about the Cormorant in Pembrokeshire

Cormorant

Phalococorax carbo – MULFRANBreeding resident

Cormorant – 2015 WeBS

Phalococorax carbo – MULFRAN – Breeding resident Maximum winter counts from all sites counted for the Wetland Bird Survey in Pembrokeshire.  Data after 2000 includes the Teifi Estuary. Main wintering sites for this species are the Cleddau Estuary, Bosherston Lakes, and Llys-y-fran Reservoir. However, large numbers can occur elsewhere, for example 50-60 in Fishguard Harbour […]

Cormorant – 2003-07 breeding

Phalocrocorax carbo – MULFRAN – Breeding resident Comparison with previous atlas: 1984-88 2003-07 Breeding confirmed 13 13 Breeding probable 1 2 Breeding possible excluded from total excluded from total No of tetrads occupied 14 (of 478) 15 (of 490) Percentage of tetrads 2.9% 3.1% The largest colony of Cormorants is on St Margaret’s Island and […]

Cormorant – 1994

Phalocrocorax carbo – MULFRAN – Breeding resident 1984-88 Breeding confirmed 13 Breeding probable 1 Breeding possible excluded from total No of tetrads occupied 14 (of 478) Percentage of tetrads 2.9% Mathew (1894) noted Cormorant colonies at Ramsey, Skomer, Lydstep Head and Pointz Castle, Lockley et al. (1949) adding St Margaret’s Island, St Bride’s Stacks, Pwll Deri and […]

Cormorant – 1980s winter

Phalococorax carbo – MULFRAN – Breeding resident The BTO winter atlas showed that Cormorants were present in most coastal and estuarine 10km squares and on some inland waters during the winters of 1981-82, 1982-82 and 1983-84. The darker the colour, the higher the relative total count for each 10km square.  The darkest blue represents over 25 birds. […]

Cormorant – 1949

Species account from the Birds of Pembrokeshire, 1949, by Lockley, Ingram and Salmon.

Cormorant – 1894

Phalacrocorax carbo – A common resident. There are nesting stations at various places on the coast, on Ramsey and Skomer Islands, &c. There are some twenty to thirty pair of Cormorants about Lydstep Head, near Tenby, as Mr. C. Jefferys informs us; a colony nests on trees at Slebech ; and some Herons that nested at Poyntz Castle on St. […]