Great Black-backed Gull (Larus marinus)

(last update: July 12, 2015)

Great Black-backed Gull 2cy February

Ireland - GBBG Larus marinus on island Ireland's Eye, near Dublin.

From the north, looking over Irelands Eye and Howth harbour.

(© Copyright Eric Dempsey - Dublin Birding)
Ireland's Eye is a small island lying just north of Howth. In summer it is home to large numbers of breeding seabirds including Irelands newest Gannet colony. The only access to Ireland’s Eye is by a regular small boat service that runs during the summer months from the west pier in Howth Harbour. The landing point is on the north side of the island, close to the Martello Tower. From here follow the narrow, path that runs along the north end of the island from which there are several excellent vantage points that give good view over the cliffs. The area at the back of the Martello Tower is the best area to see Puffin in summer. Care should be taken to avoid walking on eggs and chicks as this path leads through a colony of Great Black-backed and Herring Gulls. At the highest point of the island is a sea stack just offshore that holds breeding auks and Gannets. From here a path continues south and eventually leads to the beach on the west side of the island. This then brings you back to the Martello Tower. Ringed Plovers and Oystercatchers nest on the beach so care should be taken to avoid nests when walking the beach.

It is always worth asking the boatman to bring the boat around the island on the return journey. This provides excellent views of the breeding seabird cliffs and the Gannet colony. It should be noted that the paths on Ireland’s Eye are frequently overgrown by bracken in summer and that in wet weather, the cliff paths can be quite unsafe.

View on harbour of Howth, prime spot for reading blue rings at less 1 km distance.

Birds found on Ireland’s Eye

Seabirds found here in summer include Fulmar, Cormorant, Shag, Gannet, Lesser Black-backed Gull, Herring Gull, Great Black-backed Gull, Kittiwake, Guillemot, Razorbill, Black Guillemot and Puffin. Sedge Warblers and  Whitethroats also breed on the island while offshore Sandwich, Common and  Arctic Terns are found. Manx Shearwaters are often found in large numbers in late summer on the sea behind the island. Oystercatcher and Ringed Plover breed on the beaches. In winter Greylag Geese are occasionally found here.

Great Black-backed Gulls

Chris Honan would be grateful if birders would look out for gulls wearing blue rings. Great Black-backed, Lesser Black-backed and Herring Gulls were ringed on Ireland’s Eye during the summer months of 2009 and 2010 as part of a continuing study. 

The birds have blue rings with white codes on their left legs and BTO metal rings on the right.  Reports can be sent directly to gulls@eircom.net.

Great Black-backed Gull (Larus marinus) 1VA 1CY-2CY, November 2013 & January 2014, Dublin, Ireland. Picture: Graham Prole.	Great Black-backed Gull (Larus marinus) 1VU 1CY, November 30 2013, Dun Laoghaire West Pier, Ireland. Picture: Graham Prole.
Great Black-backed Gull (Larus marinus) 1VV 2CY, January 18 2014, Sandycove, Ireland. Picture: Graham Prole.	Great Black-backed Gull (Larus marinus) 3EP 1CY, November 04 2013, Howth, Ireland. Picture: Graham Prole.
Great Black-backed Gull (Larus marinus) 1RK 3CY, November 17 2013, Bullock Harbour, Ireland. Picture: Graham Prole.	Great Black-backed Gull (Larus marinus) 1LC 3CY, November 02 2013, Bullock Harbour, Ireland. Picture: Graham Prole.
Great Black-backed Gull (Larus marinus) 1AS 5CY, January 02 2014, Howth, Dublin, Ireland. Picture: Graham Prole.	Great Black-backed Gull (Larus marinus) 2CN 6CY, January 02 2014, Howth, Dublin, Ireland. Picture: Graham Prole.

SITE SYNOPSIS - SITE NAME: IRELAND'S EYE SPA - SITE CODE: 004117

Ireland’s Eye is an uninhabited island located about 1.5 km north of Howth in Co. Dublin. The island has an area of c.24 ha above the high tide mark. The underlying geology is Cambrian greywhackes and quartzites. These rocks form impressive near-vertical cliffs, reaching 69 m, along the northern and eastern sides of the island, with scattered exposures elsewhere on the island and especially in the high northern half. A tall stack, which is completely cut off from the main island at mid to high tide, occurs at the eastern side of the cliffs. A sandy beach, backed by low sand hills, occurs at Carrigeen Bay on the western shore, while a shingle beach extends from Carrigeen to Thulla Rocks. Elsewhere the island is covered by glacial drift. A low-lying, sparsely vegetated islet, known as Thulla, occurs a little to the south of the island, and an extensive area of bedrock shore (heavily covered by brown seaweeds) is exposed at low tide between Thulla and the main island. There are no watercourses or springs on the island, though two small rainwater ponds form during winter in the north-west and north-east sectors. A substantial area of the sea to the north and east of the island, where seabirds socialise and feed, is included in the site.

The drift soils support a plant community of Bracken (Pteridium aquilinum) and various grasses, especially Red Fescue (Festuca rubra), along with Bluebells (Hyacintoides non-scripta), Common Dog-violet (Viola riviniana) and Pennywort (Umbilicus rupestris). The localised Spring Squill (Scilla verna) is a feature of the flora. The cliff maritime flora includes Rock Spurrey (Spergularia rupicola), Sea Stork’s-bill (Erodium maritimum), Rock Samphire (Crithmum maritimum), Golden Samphire (Inula crithmoides) and Sea Lavender (Limonium binervosum). The small area of shingle vegetation supports two Red Data Book plant species, Sea Kale (Crambe maritima) and Henbane (Hyoseyamus niger). The seabird populations exercise a strong influence on the vegetation over much of the island and in places only those plants which can survive liberal spraying with guano manage to survive. Hogweed (Heracleum sphondylium), Nettles (Urtica dioica) and Slender Thistle (Carduus tenuiflorus) are common in such areas.

Ireland’s Eye has important populations of breeding seabirds. In 1999 the following were counted: Fulmar 70 pairs; Gannet 142 pairs, Cormorant 306 pairs; Shag 32 pairs, Lesser Black-backed Gull 1 pair; Herring Gull c.250 pairs; Great Black-backed Gull c.100 pairs; Kittiwake 941 pairs; Guillemot 2,191 individuals; Razorbill 522 individuals. In 2001 the following were counted: Gannet 202 pairs; Cormorant 438 pairs; Shag 39 pairs; Great Black-backed Gull 110 pairs; Kittiwake 1024 pairs; Guillemot 2948 individuals; Razorbill 686+ individuals. Puffin was formerly common, but nowadays not more than 20 individuals occur. Black Guillemot also breeds, with 15 individuals recorded in 1998. Manx Shearwater has bred in the past. The Gannet, Cormorant, Herring Gull, Great Black-backed Gull, Kittiwake, Guillemot and Razorbill populations are of national importance. When the Cormorant population is considered as part of a larger grouping with the colonies on nearby Lambay and St. Patrick’s Island, this population is of international importance. The Gannet colony is of particular note as it is one of five in the country and the only one on the east coast. It is also notable that it has only been established as recently as the late 1980s.

Several pairs each of Shelduck, Oystercatcher and Ringed Plover breed, while the island is a traditional site for Peregrine Falcon, a species listed on Annex I of the EU Birds Directive. In winter small numbers of Greylag and Pale-bellied Brent Geese graze on the island and it is used as a roost site by gulls and some waders.
Ireland’s Eye is now one of the best monitored sites in the country, with the breeding seabirds having been systematically censused using standard methods almost annually since 1990 (and also in 1986). Prior to that, census data are available for 1969/70 from the Operation Seafarer project. The present status of most of the breeding seabirds on Ireland’s Eye appears favourable. The principal direct threat to the nesting birds is potential disturbance from visitors to the island. While the present level of disturbance does not appear to be having adverse impacts on the majority of the breeding birds (most of which are on relatively inaccessible cliffs), regulation and management of visitors to the island may be necessary in the future. Brown rats are long established on the island but their recent status is not well known. It is likely, however, that the presence of rats may be a factor in keeping the Puffin population at a low level.

This relatively small island is of high ornithological importance, with seven seabird species having populations of national importance. The regular presence of a breeding pair of Peregrine Falcon is also of note.
27.02.2002

Tables:

below: graph corresponding to data from table 1. n=31. Distribution of replaced scapulars in February 2cy GBBG, separated into Upper Scapulars, Lower scapulars and for Total scapular region. Classification in 6 classes, running from 0% (no 2nd gen scaps) to 100% (all scaps in a region have been replaced).

The group of birds which score 100% 2nd gen scapulars gradually grow; remember however that 1st cycle birds, especially in March-April, grown fresh upper scapulars again, most probably 3rd gen feathers (feather condition was not scored by us). Figures in the graph may be read reverse, the presence of juvenile feathers decrease over time.

below: Great Black-backed Gull JA804 illustrates differences in colour and pattern between old juvenile 1st generation scapulars and fresh buffish 2nd generation feathers. Bird ringed as pullus on June 12 2012 at Salvøy, Karmøy, Rogaland, Norway (59°17'54"N 005°12'27"E). Picture: Jean-Michel Sauvage, September 28 2012, Boulogne-sur-Mer, NW France.

below: Distribution of replaced scapulars for "Total scapular region" for months August in hatch year until commencement of first complete moult in April. Classification in 6 classes, running from 0% (no 2nd gen scaps) to 100% (all scaps, including long rear scaps, have been replaced). Only ringed birds, n=238.

Great Black-backed Gull (Larus marinus) 1st cycle (2CY), February 24 2016, IJmuiden, the Netherlands. Still juvenile plumage.