Rockabill is a bird island with a lighthouse on it. The larger of its two granite rocks, about six kilometres (four miles) east of Skerries, holds the biggest roseate tern colony in Europe: around 1,200 pairs in a good year, roughly 80% of the whole northwest European population. You can’t land. The terns have the run of the place through the breeding season, and the only way to see it is from a boat.
The rock and its name
There are two islets, split by a channel about 20 m wide. The larger, ‘The Rock’, carries the lighthouse; the smaller is ‘The Bill’. The Irish name is Carraig Dábhiolla, ‘Two-bill Rock’. An alternative form sometimes seen, Carraig Dhá Bheola or ‘Two Lips Rock’, is probably just a corruption of it. Walls and old outbuildings on The Rock have trapped enough soil over the years for tree mallow to take hold, and that cover is a good part of why the birds do so well here.
Building the light
Drogheda’s Harbour Commissioners first asked for a light on Rockabill in 1837, arguing that the ships using the port would happily pay a toll for it. The board took its time. The work was sanctioned in 1853 and given to the Burgess brothers, who raised a 32 m cylindrical tower from Mourne granite and Milverton limestone between 1855 and 1860. The whole job came to £13,248 15s 3d, and the light was first lit on 1 July 1860.
The station changed with the times. The original coal-gas lamp gave way to paraffin, then to electricity in 1980 and solar power in August 2006. A fog signal, set up around 1917–18, sounded until it was switched off for good in April 2006. The light was automated in 1989 – Irish Lights records the changeover as 1 April – which ended the era of resident keepers.
The terns
Since 1989 the rock has been managed for its birds by BirdWatch Ireland, and it is a Special Protection Area under the EU Birds Directive. The roseate tern is the reason: numbers have climbed to around 1,200 pairs, about 80% of the northwest European population, nesting alongside thousands of common terns and smaller numbers of Arctic terns and black guillemots. Wardens manage the habitat, put out nest boxes and keep predators off the eggs. Grey seals haul out on the rocks between the islets, most often early in the morning.
Seeing it
Landing is off-limits during the tern breeding season, so the way to see Rockabill is from the water. Skerries Sea Tours runs 75-minute trips out to the rock from late April to early October, €35 a head, with commentary on the lighthouse and the birdlife along the way. Sailings are weather-dependent. The Irish Sea turns quickly, and trips are called off in strong wind or poor visibility, so confirm your departure with the operator on the day.
If a boat isn’t on the cards, the lighthouse is a clear landmark from the shore at Balbriggan, Skerries, Loughshinny and Rush. Skerries itself is on the northern commuter rail line from Dublin, a short walk from the harbour where the tours leave. For photographs, a long lens (200 mm or more) lets you frame the terns without crowding them, and the black band on the white tower reads best in early light.
The numbers
| Detail | Information |
|---|---|
| Coordinates | 53°35.811′ N, 06°00.297′ W |
| Tower height | 32 m |
| Focal height | 45 m above sea level |
| Light character | Fl WR 12s |
| Range | White 18 nm / Red 14 nm (Irish Lights) |
| Automated | 1989 |
| Tour operator | Skerries Sea Tours |
| Tour duration | 75 minutes |
| Adult fare | €35 |
| Season | Late April – early October |
Irish Lights gives the range as 18 nautical miles (white) and 14 (red); some sources quote the reduced post-2006 figures of 17 and 13 after the switch to solar. The lighthouse is owned by the Commissioners of Irish Lights and is not open to the public.
June and July are the peak, when the terns are in full plumage and feeding chicks and the air over the rock is loud with them. Book those weeks early, as seats go quickly for weekends and school holidays.