Herring Gull – WeBS 2020-21

Larus argentatus – GWYLAN Y PENWAIG – Breeding resident and winter visitor

Updates to the Wetland Bird Survey counts for this season.

Counting gulls for WeBS is optional, and has only been regularly included at Pembrokeshire sites since 1993. Gulls are still not counted on a few sites.

Note that totals for any month this season may be updated as more counts come in.

Annie Haycock (BBS & WeBS local organiser)

More about the Herring Gull in Pembrokeshire

Herring Gull – 2003-07 breeding

Larus argentatus – GWYLAN Y PENWAIG – Breeding resident and winter visitor

Comparison with previous atlas:

1984-882003-07
Breeding confirmed6369
Breeding probable35
Breeding possibleexcluded from totalexcluded from total
No of tetrads occupied66 (of 478)74 (of 490)
Percentage of tetrads13.8%15.1%

Only 40 years ago Herring Gulls could be found breeding in almost every cove and on every cliff around the Pembrokeshire coastline but in the early 2000s they are predominantly confined to the offshore islands. Unfortunately we know rather little about their historic numbers, perhaps because they appeared so common they were never counted.  Indeed the eggs were widely collected for human consumption at least up to the 1960’s.

Herring gulls feed along the coastline, in the fields and formerly at rubbish tips and around the docks. They will readily take any food offered to them.  Their ability to adapt to available food sources enabled them to increase in numbers dramatically, around 10% per year, between the 1950’s and the early 1970’s, when there was abundant waste available on rubbish tips and in the docks at Milford Haven.

The subsequent dramatic decline of c.80% in the early 1980’s was almost totally caused by a botulism outbreak which killed many hundreds of adult birds (Sutcliffe 1986).

It is clear from the map that Herring Gulls still breed all around the coastline of the county, but today mostly in small numbers and often on isolated offshore rocks.  The main concentrations are on the islands and in particular on Caldey, where numbers have recovered from a low of 675 pairs in 1998 to just over 2,000 in 2008, making it one of the largest colonies in the UK.  On the other islands the populations have not recovered: on Skomer and Skokholm it has been relatively stable at just under c. 450 to 600 pairs and 250 to 350 pairs respectively during the last decade.  The islands of Ramsey and the Bishops hold around 300 pairs and there are small colonies of 50 to 200 pairs on St Margaret’s and Grassholm Islands, Dinas Head and along the Castlemartin coastline. The whole county population in 2003-07 was probably in the order of 4,000 pairs, compared with the peak 1969 counts of 12,700.

Steve Sutcliffe

Rees G.H., Haycock R.J., Haycock A, Hodges J.E., Sutcliffe S.J., Jenks P, and Dobbins R. 2008, Atlas of Breeding Birds in Pembrokeshire 2003-07. Pembrokeshire Bird Group.

SUTCLIFFE. S.J.1986. Changes in the gull populations of south west Wales. Bird Study, 33: 91-97

More about the Herring Gull in Pembrokeshire

Herring Gull – 1994

Larus argentatus – GWYLAN Y PENWAIG – Breeding resident and winter visitor

Map produced by the West Wales Biodiversity Information Centre
1984-88
Breeding confirmed63
Breeding probable3
Breeding possibleexcluded from total
No of tetrads occupied66 (of 478)
Percentage of tetrads13.8%

Mathew (1894) commented on an increase in the number of breeding herring gulls in the wake of the sea birds preservation act of 1869.  Lockley et al (1949) traced a continued increase, despite large scale collection of gulls eggs; for example, about 3000 eggs were taken in one season at Skokholm, from a colony of 1000 pairs. 

Limitations were put upon the collection of eggs at Skokholm and Skomer and the harvesting of eggs generally declined throughout the county as social conditions changed.  Herring gulls accelerated their rate of increase, a process aided by the abundance of food at local refuse dumps.  In 1969 Operation Seafarer recorded 11740 pairs breeding in Pembrokeshire, including 1350 pairs on Skokholm and 2200 pairs at Skomer.  Most nest on the cliffs of the mainland and islands but roof nesting has been noted at Tenby and the Esso refinery at Herbrandston and suspected elsewhere.

Herring Gulls began to decrease in the lat 1970s, coinciding with the introduction of black plastic bags for refuse collection.  In warm conditions these bags make good incubators for the bacterium Clostridium botulinum which is thought to have poisoned the gulls feeding on the rubbish tips.  By the time the Seabird register survey of 1985-87 was conducted the breeding population had shrunk to 4062 pairs, with 613 pairs at Skomer, and 321 at Skokholm.  Changes in rubbish tip operations are coming into force which will make harmful food less accessible to gulls, and this may reverse the decline.

Herring gulls are not confined to scavenging on rubbish tips, but feed widely across the fields of the county, where earthworms form an important part of their diet.  They also feed around the rocky shores and the estuaries and pick up fish offal at Milford Docks, though fewer catches are landed there than in the past.

Although generally regarded as sedentary, many of our herring gulls disperse from the breeding grounds in the winter, certainly as far as the upper Bristol Channel.  Juveniles can venture further, with recoveries from North Wales, Ireland, France, Holland and Poland, as well as of an Irish-bred bird visiting Pembrokeshire.

Small numbers of Scandinavian birds of the subspecies argentatus were detected in the winters of 1985 to 1987, with records occurring between 11 December and 22 February.

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

More about the Herring Gull in Pembrokeshire

Herring x Lesser Black-backed Gull hybrids

Harris, M.P. 1970. Abnormal migration and hybridization of Larus argentatus and L. fuscus after interspecies fostering experiments. Ibis 112: 488-498.

Summary

Between 1962 and 1966 eggs of Larus argentatus and L. fuscus were interchanged andalmost 900 young were reared by the wrong species. Many of these cross-fostered young were later recovered or retrapped on and away from the colonies.

The British population of argentatus is sedentary and ringed birds are not recovered outside Britain, whereas fuscus normally migrates. Many cross-fostered argentatus migrated to France, Spain and Portugal, areas where fuscus is common, but they did not migrate as far as the control fuscus. It is possible that these cross-fostered argentatus had followed their foster parents when these migrated, but this is unlikely as the cross-fostered fuscus also migrated although their foster parents would have remained in Britain.

Despite wide ecological and behavioural overlaps, interbreeding between L. argentatus and L.fuscus is exceedingly rare. However, as a result of cross-fostering experiments, 31 and 40 mixed pairs were found on Skokholm in 1968 and 1969 respectively. Although some of the birds involved were unringed it is probable that all the adults in mixed pairs had been cross-fostered. Other cross-fostered birds were found mated with their own species and it appears that the sex of the imprinted birds was important. Female gulls will usually only mate with males of their own species, or in the case of the cross-fostered birds, with males of their foster species. Males will mate with either species.

Evidence is given that suggests that the colour of the mantle and wings is important in species recognition at long range, and the colour of eye-ring and join of the mandibles for recognition at short range. The role of voice is uncertain but general behaviour is probably unimportant.

The original paper can be purchased here 

 A later paper is downloadable here Dr M. P. Harris, C. Morley & G. H. Green (1978): Hybridization of Herring and Lesser Black-backed Gulls in Britain, Bird Study, 25:3, 161-16

More about the Lesser B-B Gull in Pembrokeshire

Herring Gull – 1980s winter

Larus argentatus – GWYLAN Y PENWAIG – Breeding resident and winter visitor

The BTO winter atlas showed that Herring Gulls were present in most 10km squares 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 400 birds.

All squares were used for feeding purposes but the largest concentrations were at coastal roost sites 

Graham Rees 

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 Herring Gull in Pembrokeshire

Herring Gull – 1949

Larus argentatus argentatus

This species had already increased considerably by 1894, and was then a common resident, and seems to have continued to increase steadily.  There are colonies of varying size all along coastal cliffs and on the islands (eg 300 pairs Newport Head, 300 pairs Skokholm, 650 pairs Skomer – all in 1946)

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

More about the Herring Gull in Pembrokeshire

Herring Gull – 1894

Larus argentatus – A common resident.

The Herring Gull may be seen on our coasts all the year, and nests in great numbers upon the various islands, and also on many of the cliffs on the coasts. Since the Sea Birds’ Preservation Act this Gull has greatly increased in numbers, and on Skomer Island devours so many of the young rabbits, as to occasion serious loss, as we were informed by Mr. Vaughan Davies, the tenant. One of the sights of St. David’s is the number of Herring Gulls that may always be seen in the fields surrounding that romantic little cathedral city. In the spring our fields at Stone Hall were visited by flocks of Herring Gulls, and, at all times of the year, in rough weather, numbers of the birds forsaking the shores would be seen searching the fields for food far inland.

We have received from Mr. C. Jefferys, of Tenby, a very pretty photograph of a Herring Gull’s nest, taken in situ, with the three speckled eggs clearly visible. The nest is a large, untidy structure of grass.

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

More about the Herring Gull in Pembrokeshire

Herring Gull

Larus argentatus – GWYLAN Y PENWAIG – Breeding resident and winter visitor

Herring Gull – WeBS 2020-21

Larus argentatus – GWYLAN Y PENWAIG – Breeding resident and winter visitor Updates to the Wetland Bird Survey counts for this season. Counting gulls for WeBS is optional, and has only been regularly included at Pembrokeshire sites since 1993. Gulls are still not counted on a few sites. Note that totals for any month this […]

Herring Gull – 2003-07 breeding

Larus argentatus – GWYLAN Y PENWAIG – Breeding resident and winter visitor Comparison with previous atlas: 1984-88 2003-07 Breeding confirmed 63 69 Breeding probable 3 5 Breeding possible excluded from total excluded from total No of tetrads occupied 66 (of 478) 74 (of 490) Percentage of tetrads 13.8% 15.1% Only 40 years ago Herring Gulls […]

Herring Gull – 1994

Larus argentatus – GWYLAN Y PENWAIG – Breeding resident and winter visitor 1984-88 Breeding confirmed 63 Breeding probable 3 Breeding possible excluded from total No of tetrads occupied 66 (of 478) Percentage of tetrads 13.8% Mathew (1894) commented on an increase in the number of breeding herring gulls in the wake of the sea birds […]

Herring x Lesser Black-backed Gull hybrids

Harris, M.P. 1970. Abnormal migration and hybridization of Larus argentatus and L. fuscus after interspecies fostering experiments. Ibis 112: 488-498. Summary Between 1962 and 1966 eggs of Larus argentatus and L. fuscus were interchanged andalmost 900 young were reared by the wrong species. Many of these cross-fostered young were later recovered or retrapped on and away from the colonies. […]

Herring Gull – 1980s winter

Larus argentatus – GWYLAN Y PENWAIG – Breeding resident and winter visitor The BTO winter atlas showed that Herring Gulls were present in most 10km squares 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 400 birds. All squares […]

Herring Gull – 1949

Larus argentatus argentatus This species had already increased considerably by 1894, and was then a common resident, and seems to have continued to increase steadily.  There are colonies of varying size all along coastal cliffs and on the islands (eg 300 pairs Newport Head, 300 pairs Skokholm, 650 pairs Skomer – all in 1946) R.M.Lockley, […]

Herring Gull – 1894

Larus argentatus – A common resident. The Herring Gull may be seen on our coasts all the year, and nests in great numbers upon the various islands, and also on many of the cliffs on the coasts. Since the Sea Birds’ Preservation Act this Gull has greatly increased in numbers, and on Skomer Island devours so many of the young rabbits, as […]

Herring Gull

Larus argentatus – GWYLAN Y PENWAIG – Breeding resident and winter visitor