Dalkey Island Tern Project
South Dublin members at Coliemore Harbour for Dalkey Tern Watch 2013 (picture: Ronan Browne)
The South Dublin Branch have been taking an active interest in the small colony of terns that breed on rocks off Dalkey Island since the summer of 1995. The original initiative came from BirdWatch Ireland HQ when it was hoped that Roseate Terns might be encouraged to breed among the Common and Arctic Terns that nest on the outcrop of rock known as the Maiden's Rock (aka Corrig).
Maidens Rock with Howth in the background - May 2005
(picture: Michael Ryan)
Branch volunteers took nest boxes out and for the first few years they also took out a mobile generator and drills to bolt the nest boxes to the rock. Initially, funding was made available for three years by InterReg for a warden to monitor progress. Since then branch members have taken on the task. Although generally safe from human disturbance and predators the birds on Maiden's Rock do have to contend with the threat of summer storms, especially from the north-east. Sadly, on a number of occasions the breeding colony has been wiped out by high winds and waves. One consequence of these storms was that some of the birds, predominately Arctic Terns, moved across to Lamb Island, the large outcrop joined to Dalkey Island until it is cut off at high tide.
Setting out nest boxes on the Maidens Rock (pictures: Michael Ryan)
In other years usually one or two pairs of birds have attempted to nest there with mixed results, safe from the seas but in danger from rats and the goats that have been on the island for many years. No malice is intended by the goats but they cause great consternation among the birds when they wander among the nests feeding off the sparse vegetation and possibly crushing eggs or chicks.
The birds colonising this area prompted a new plan from Head Office to fence off some of Lamb Island, put out tape lures and decoy birds and hopefully attract Roseate Terns to nest in the enclosed area. Dun Laoghaire-Rathdown Parks Department offered help and labour to construct the fenced area. Branch members made the nest boxes and Tom Kealy made decoy terns from decoy Magpies, which he modified to resemble terns.
Ringing Terns on the Maidens Rock (pictures: Brian Gormley)
All the hard work paid off in 2003 when five nest boxes were occupied by Roseate Terns who fledged six chicks. After the loss of Roseate Tern eggs to 'collectors' at Our Lady's Island Lake in that same year, it was decided to keep the news under wraps until after the birds had departed.
Terns in Ireland
There are five species of tern breeding in Ireland with another ten occurring as vagrants or on passage. They all look like a small slender gull, but with long pointed wings. Their distinct forked tail has given them the name 'Sea Swallow'. They hover and dive to catch small fish and sand eels.
Terns arrive on our shores in April - May and depart around September. Most species spend the winter along the west coast of Africa, although the Arctic tern is known to travel as far as Antarctica.
Tern nest boxes (pictures: Tom Kealy (left) Michael Ryan (right))
Terns at Dalkey
This tern breeds around our coast and on some inland lakes. Around 20-25 pairs nest every year on Maiden's Rock laying 2-3 eggs each. Several of the nest boxes put out for the Roseate Terns are used by Common Terns. The eggs take about 3 weeks to hatch and another 3-4 weeks until the chicks can fly.
This tern is less widespread in Ireland than the Common Tern, but a few pairs breed amongst the Dalkey colony. Slightly smaller and more delicate than Common Tern, they are the ultimate long-distance traveler, covering over 10,000 miles on their migration journeys each year.
Roseate Terns at Dalkey, June 2010 (picture: Michael Ryan)
In late summer several hundred Roseate Terns can be seen roosting each evening on Maiden's Rock. These are mostly birds that have bred on Rockabill, gathering before their migration to Africa. It is hoped that in time some of these will return to breed at Dalkey, increasing their foothold in Ireland. The nest boxes that can be seen on the Maiden's Rock and in the enclosure on Lamb Island have been placed there to provide shelter should they attempt to breed at this site.
Roseate Terns are a globally threatened species. Ireland boasts the largest colonies in Europe with over 550 pairs nesting at Rockabill, off Skerries in north Co. Dublin and up to 120 pairs at Our Lady's Island Lake in Co. Wexford.
Roseate Terns need help to increase their numbers. They prefer to nest under cover or in vegetation and they readily use man-made nest boxes. They happily breed among colonies of other tern species where they gain protection from predators.
For the 2013 summary please click HERE.
Terns nested on Maiden's Rock and Lamb Island. The storm in early June caused the loss of two active Roseate Tern nests, both in nestboxes that had been secured firmly to the rock. Subsequently, an Arctic Tern colony numbering at least 20 pairs hatched young on Lamb Island.
One pair of Roseates and 25 Common and Arctic Tern nests were noted.
In May nest boxes and gravel were brought across to Maiden's Rock. The Terns will pick up the gravel and shape it into a nest, which will help prevent the eggs being washed away by waves or heavy rain. Sadly due to a north-easterly storm in early June all the birds that were nesting, including a pair of Roseate Terns, left and did not return! In addition, Arctic Terns that had nested on the adjacent Lamb Island also left, possibly disturbed by goats or humans. A bird that had been ringed on Maiden's Rock was found in Dublin Port, where there is a very successful artificial tern breeding platform so there is a chance that the Dalkey birds moved elsewhere to breed.
More next boxes and gravel were taken out but as the weeks of May passed there were no birds to use them! Then, more storms occurred and the nest boxes were damaged and it did not look too good for nesting. However on the 1st June there were over 30 terns sitting on Maidenís Rock, many mating, some looking like they were already nesting and in the middle of them a glorious Roseate Tern standing outside one of the surviving nest boxes. Not just standing beside it, but going in and sitting, evidently planning on laying eggs there. By Bank Holiday Monday the pair of Roseate Terns were in the box and the rest of the rock was buzzing with activity. Some were mating and some sitting, presumably on eggs. Once they arrived they hadn't wasted any time but they didn't have it easy with the weather. Nevertheless, 2008 was a success with two Roseate Tern chicks fledged and an Arctic Tern successfully nested in one of the nest boxes, usually something that only Roseate Terns will do.
The project began late, before ending abruptly and disastrously. The birds hadn't nested by their usual time in May and there was concern about the abundance of Sand Eels. Over thirty five nest boxes, a few hundredweight of gravel and four decoy terns shipped from the USA sat unused on the rock. By mid-June some Common Terns began to nest, however within a week there were strong north-easterly winds and rough seas, which washed over the rock destroying nests and decoy terns. Sadly, 2007 was the first year since the project began that no terns nested on the Maiden's Rock. The only small consolation was that tern numbers in Dublin Port and on Rockabill were up.
The Maiden's Rock terns had a mixed breeding season in 2006. Overall, the numbers of terns breeding were slightly down on 2005 and only one pair of Roseate Tern bred raising two chicks. There were about 50 Common and Arctic Tern nests and they raised about 30 chicks. This was down on last year probably due to poor weather just as chicks were hatching. Unlike previous years when storms destroyed the nests, this year's damage was caused by heavy rain which saturated and washed away the eggs. Had it held off just a few weeks the newly hatched chicks could have sheltered in the nest boxes.
The last of the nest boxes were brought out on the 15th May, bringing the total number of boxes to 54. The boxes are numbered and can be read from land. Later some slabs to hold down the boxes and gravel (courtesy of Mackey's Garden Centre) to spread around the boxes to entice nesting were added. Thanks to funding from DLRCC and the Heritage Council, Eugene Archer will act as warden during the breeding season. By the end of the season two pairs of Roseate Terns hatched two chicks each and the colony included 79 Common and Arctic Tern nests, mainly of the former.