Guest Blog by Tara Adcock, BirdWatch Ireland

It’s been an exciting few weeks on the Dalkey Islands, with the first Tern eggs discovered on the 22nd of May, followed by the first Tern chick of the season on the 13th of June

​The colony is split between three islands; Maiden Rock which has the only Common Tern pair nesting on the islands this season, Lamb Island, and Dalkey Island, which is by far the largest of the three islands.
 
Thus far, we have 14 chicks (all Arctic Terns), and 16 nests with eggs. The chicks are now getting big enough that we have been able to carry out the first ringing visit to the colony.
 
Both Lamb Island and Maiden Rock are restricted from access to members of the public during the breeding season to protect ground nesting birds. We also ask that on Dalkey Island, visitors are mindful of breeding birds, keep all dogs on leads and do not get too close to the sub - colonies. A good rule of thumb is, if the birds are acting agitated, you're probably a little too close. :)  

This year is the first time over the course of the project that Tern chicks have survived long enough on Dalkey Island to be ringed. In fact, these are the first Tern chicks to ever be ringed on Dalkey Island itself!

​This is an amazing result which is due in large part to the tenacity of their parents, which are quite literally not afraid to knock some heads in the line of duty!

​The rings which these Terns have been fitted with will feed into a wider understanding of how long these birds live, the rate of survival for this species, and their migration routes. Not bad for a tiny piece of bling! 

Colour ringing has revealed previously unknown facts about the lives of many species of birds, including Common and Arctic Terns. For instance, we know from recoveries of ringed Common Terns which bred in the UK and Ireland, that these birds overwinter in the western portion of Africa, as far south as Namibia (retrieved from BirdWatch Ireland’s Dublin Bay Birds Project).

Resightings of ringed Arctic Terns and at sea surveys also provided the first indications that these birds migrate to Antarctica where they overwinter before returning north, some as far as the Arctic Circle, to breed. Geolocators have proven these theories correct in recent years, and also revealed that these birds fly a circuitous route along the coastlines of South America and Africa, using prevailing winds to help them along.
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Arctic Terns, weighing less than 125 grams or a quarter of a bag of sugar, migrate the equivalent of three to nearly four round trips to the moon in their lifetime! (Barrett 2016; RSPB 2018).  All going well, the Common and Arctic Tern chicks on the Dalkey Islands will begin their journeys to Africa or Antarctica respectively, at the end of the season.

A successful Tern breeding season on the Dalkey Islands is vital to the long – term success of the colony. The last couple of years have seen successive poor breeding seasons for these species on the Dalkey Islands due to predation, which has led to a reduction in the number of returning Common and Arctic Terns to the nesting grounds.
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Terns are colonial breeders, which means that they typically prefer to nest in groups. This provides better defence against potential predators, as the more birds mobbing an intruder, the less likely it is to snatch eggs or chicks, and it is also less likely that a pairs brood will be predated. Therefore, the smaller the colony, the more vulnerable it is to predation.

​Both Common and Arctic Terns are Amber listed species according to the Birds of Conservation Concern in Ireland. This means that although they are not considered on the verge of extinction in Ireland, they are vulnerable. By contrast, the Roseate Tern, a cousin of the Common and Arctic Tern, is considered Europe’s most endangered seabird. The Roseate Tern is less feisty than its more aggressive cousins, and as such prefers to nest among large colonies of Common and Arctic Terns upon whom it depends to help drive away intruders. 

The Dalkey Tern Conservation Project is part of the larger EU LIFE Roseate Tern Recovery Project. One of the aims of this project is to reintroduce the Roseate Tern to the Dalkey Islands, where as recently as 2004 eleven pairs bred. The reason it is considered critical to re-establish a Roseate Tern colony on these islands is because one colony in Ireland, Rockabill Island off the coast of north Co. Dublin, supports over 50% of Europe’s breeding Roseate Tern population. ​

The history of the Rockabill Roseate Tern colony is fascinating, with numbers growing from just 152 pairs in 1989 to over 1,600 pairs last year, thanks to intensive and ongoing management by BirdWatch Ireland. However, this high proportion of Europe’s breeding Roseate Tern population on one island is akin to having all of your eggs in one basket. A number of poor breeding seasons on Rockabill Island could have long term consequences for the European population of this species.

​Therefore, diversifying the availability of suitable breeding habitat is crucial to the long - term success of the Roseate Tern.

To do this, we need to either remove predators such as rats through baiting, or thwart potential predators such as gulls using a 1 metre by 1 metre grid pattern of canes in the Tern colonies. This reduces access to gulls to the nesting sites on the Dalkey islands. The three species of gulls present throughout the breeding season have wings spans of 1.25m and above, while the wing spans of the Terns are .75m and smaller. Therefore, the idea is that gulls passing overhead simply will not fit between the canes and therefore have less access to the Tern nesting site.
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To increase the number of Arctic and Common Terns nesting on the islands, we hope to use decoys (wooden or plastic figures which look like Terns), and audio of Common and Arctic Terns to attract these species to the islands next season. 

​Finally, we’ll be walking on eggshells (not literally!) over the coming weeks and keeping everything crossed for a successful year, but so far this season is looking good! However, we are not out of the woods yet as Tern chicks are extremely vulnerable to predation, weather events and disturbance from people and dogs. We’ve put out chick shelters, nest boxes, gravel and canes to give them the best chance possible and will continue to monitor and to the best of our ability protect the small but mighty Tern colony on the Dalkey Islands. 

If you want to find out more about the Dalkey Island Tern Conservation Project, feel free to drop by the Tern Watch Events on Tuesday nights from 5-8 pm at Coliemore Harbour this July. The Dalkey Tern Warden and members of the South Dublin BirdWatch Ireland branch will be on hand to show you the Tern colony, the surrounding wildlife and answer any questions you may have. Telescopes and binoculars are available to use!
 
In addition, morning Tern Watch Events will be held at Coliemore Harbour from 11 – 1pm on the on the 14th and 28th of July. Following these, guided walks will be held on Dalkey Island at 2:30 and 4:15 pm, meeting at the pier on the island. For more information see the BirdWatch Ireland Facebook page and website. Thanks to everyone who has come along, I've enjoyed meeting you all, and seeing returning faces at the events! 
 
And finally, a massive thanks to Ken, Johnny and David Cunningham who have ferried us back and forth free of charge during both this and last year's nesting season. This is an incredibly generous act, and one which is greatly appreciated! If you have a chance to take the boat across to Dalkey Island with Ken and his brothers, I'd highly recommend it! 
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Barrett R. (2016). Upwind or downwind: the spring arrival of Arctic Terns at Troms, North Norway. Ringing and Migration, 35, 23-29.
 
Rauzon M.J. (2007). Island restoration: exploring the past, anticipating the future. Marine Ornithology, 35, 97–107.

RSPB (2018). Everything you need to know about Arctic Terns. Royal Society for the Protection of Birds, 1st May. Available at:
ttps://community.rspb.org.uk/ourwork/b/natureshomemagazine/posts/everything-you-need-to-know-about-arctic-terns. (Accessed 27th June 2019).

Terns breeding around the Irish Sea do not know borders and jumping across the water seems to be no issue at all. We know from GPS tagging of Arctic terns at the Skerries that some individuals venture out to shores of Ireland and Sandwich terns can move from Anglesey to Cumbria during a single season. A prospect of the roseate tern expansion from Rockabill has become increasingly likely too. It makes sense therefore that we look beyond individual colonies and share knowledge and experience amongst colony managers to strengthen management and monitoring practices and ensure maximum protection on all sites. 

An idea for the Irish Sea Tern Network is not new and the vibrant Facebook group is currently filling the space confirming that the concept for such a network is valid and deeply desired. However, in the times of screen detoxing and well-known benefits of meeting people face to face, a group of practitioners from Northern and the Republic of Ireland met in April to discuss a possibility of a more tangible liaison. I offered that the Roseate Tern LIFE Project would host the first meeting and that the programme will be impossible to turn down. 
 
While the detailed programme is not quite there, the idea is to meet on Anglesey, 17-18 October 2019 and run a mix of presentations and thematic workshops on management, monitoring and research plus to set objectives and actions for the network (if there is a consensus to form one). Please feel free to propose the topics you would like to discuss, and we will try to bring relevant experts. 
 
The LIFE project will cover the venue, lunch, dinner and tea/ coffee, but I am afraid the accommodation and transport can only be covered for speakers. We can however make an exemption for long-term volunteers and wardens who are not currently associated with any organisation.
 
I appreciate that the above might not be quite yet impossible to turn down, but please note the date and watch the space. Also, please share this message with anybody who might be interested in attending. 
 
Thank you, 
 
Daniel Piec
Roseate Tern LIFE Project Manager
daniel.piec@rspb.org.uk
07748658990

Special thanks to Tara Adcock from BirdWatch Ireland for this update on the Dalkey Islands Tern Project 
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With the arrival of the Terns to the Dalkey Islands, it’s been all hands - on deck getting the breeding sites ready for the upcoming nesting season. So far, we have counted 15 Terns (both Common and Arctic) on Maiden Rock and 5 Arctic Terns on Lamb Island. No eggs have been laid yet, although there’s plenty of courtship activity taking place with males arriving regularly with sandeels and sprat to their eager mates. While Roseate Terns have not yet made their presence known, we’re hoping that nest boxes on Maiden Rock and Lamb Island might entice a few pairs to lay down roots on the islands. Roseate Terns have bred on Maiden Rock as recently as 2016, so we’ll be keeping our eyes peeled over the coming season!

Oystercatchers, like the Terns, have also been busy, with two nests, (containing 3 eggs each), found on Lamb Island, and a courting pair spotted on Maiden Rock. 

On Tuesday, the 14th of May, Steve Newton, the Dalkey Island Tern Conservation Project Manager, and I, set out for the islands. Our first stop was Dalkey Island, where we unloaded our gear before nipping across to Lamb Island as the tide fell, (some of us more nimbly than others, with Steve thoroughly putting me to shame!). 

Our task for the day – creating a grid of alternating canes each approximately one metre apart on Lamb Island to try to deter Gulls from landing in the Tern colony and predating chicks and eggs. 

The idea behind this simple method is that at one metre distances, the canes are placed too close together for Lesser Black – backed Gulls (wingspan 135-150cm), Herring Gulls (wingspan 130-150cm) and Great Black – backed Gulls (wingspan 150-170cm) to land between, while still allowing space for the smaller Arctic, Common and Roseate Terns to fly into the colony. This was tried in 2016 on the Inner Farne and Brownsman Islands off the northeast coast of the UK with good success (Boothby et al., 2019). Fingers crossed it will help the Lamb Island subcolony over the upcoming season!

With a good proportion of the canes in place, it was time to head back to the mainland for the first Tuesday evening Tern Watch Event of the season. Johnny the boatman and his able navigator, Bowzer, were on hand to safely ferry us back across the Dalkey Sound.

​We were incredibly lucky with the weather for our first nature watching event and hopefully it’s a good omen for the upcoming season! 

In total, we spotted 17 bird and two mammalian species. The Terns were joined by diving Gannets further out to sea, and Razorbills and Manx Shearwaters on their way to and from their breeding grounds (telescopes, provided by BirdWatch Ireland, were a definite necessity for this spectacle!).
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Closer to shore, a Black Guillemot pair, which are nesting in the wall of the harbour, bobbed on the sea before taking flight, their white wing patches startling against the jet black of their bodies. Cormorants basked, wings outstretched to dry, on the rocks between Maiden Rock and Lamb Island among roosting Gulls and Terns. Grey seals, ever curious, peeked above the water at passing boats, while rabbits were a common sight bounding across Lamb Island. 

​Finally, although not of the avian or mammalian persuasion, we were treated to the spectacle of this beautiful ship passing through the Dalkey Sound toward the end of the evening.

​All in all, it was a really pleasant night and it was great to see some familiar faces from last years season popping down again to check out the Terns!

Public goodwill and understanding are integral to the success of the project. The Dalkey Islands, being on the edge of an urban hub, are ideally located for showcasing the beauty and ecology of birds along with mammals such as seals and harbour porpoises, as well as introducing people to the importance of projects such as the EU Life Roseate Tern Recovery Project.
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To this end, Tern Watch Events will continue to be held every Tuesday evening from 5 – 8pm at Coliemore Harbour, Dalkey until the 30th of July. In addition, beginning June 2nd, morning Tern Watch Events will be held every second Sunday at Colimore Harbour from 11am – 1pm, followed by three one hour Guided Walks on Dalkey Island from 2:30 – 5:30pm. A massive thank you to everyone who came down to the first Tern Watch Event of the season, and I look forward to many more inspiring morning and evenings over the coming months!

References: Boothby, C., Redfern, C., & Schroeder, J. (2019). An evaluation of canes as a management technique to reduce predation by gulls of ground nesting seabirds. International Journal of Avian Science, 161, 453-458.