Dalkey islands: Volunteers helping to 'tern' things around

The tern season on the Dalkey islands is wrapping up, and what a few months it has been! The small, but tenacious Arctic Tern colony (29 pairs), have succeeded in raising 20 chicks, including 7 on Dalkey Island itself, the first ever fledglings from the island! This is an amazing result, and one which all at BirdWatch Ireland and our funders, the EU Life Project and Dún Laoghaire – Rathdown County Council, are absolutely thrilled about, (see here in the Irish Times for more info).

Arctic Tern nest with some interesting decorations!
Photo by: Tara Adcock

Arctic Tern chick still at the fluffy stage
Photo by: Tara Adcock

First ever Arctic Tern fledgling on record from Dalkey Island itself!

Video by: Tara Adcock

On top of this, there were signs and sightings of Rock Pipit, Shelduck, Pied Wagtail and Oystercatcher chicks, along with many healthy and noisy Herring, Lesser Black – backed and Great Black – backed gull fledglings. 

Oystercatcher chick with wonderful camouflage
Photo by: Tara Adcock

Colour ringed Great Black - backed Gull chick
Photo by: Graham Prole

But today, as we wrap up, it is the volunteers and members of the community who helped and participated to an extraordinary degree over the course of the project, that I would like to ‘tern’ our attention to.

Last winter, BirdWatch Ireland with guidance from Karen Varnham of the RSPB, began working on removing Brown Rats (Rattus norvegicus), from the islands. Brown rats are an invasive species and have a devastating impact on seabird colonies when present, (see here and here for more info). Rat control is definitely one of the least glamourous tasks anyone could take on! Between handling bait stations and searching for signs of rat in the field, it calls for a strong stomach (and a lot of hand sanitiser!). 

Monitoring block with rat teeth marks beside a bait station
Photo by: Tara Adcock

Who would have thought that we could find anyone enthusiastic enough to join us in the middle of an Irish winter to help carry out such work? And yet, along came Chris Johnson and Shelly Biswell. Over the course of the three and a bit months, they were instrumental to the success of the baiting project, and their indefatigable cheerfulness was a god send!

Chris Johnson in action checking bait stations
Photo by: Tara Adcock

Shelly Biswell with her partner, Ken, out beautifying Dalkey Town
Photo by: Ken Biswell

As tern numbers on the island began to grow, we were delighted to welcome three new volunteers to the project. Tom Murphy, Sandra Jordan and James Tallon braved thistles, nettles and dive - bombing Arctic Terns as we censused nests and chick numbers on the islands. From the get-go, all three proved exceptionally able at spotting the well camouflaged chicks and were unbelievably enthusiastic even when under fire from angry tern parents!

From left to right: Tom Murphy, Sandra Jordan and James Tallon just before heading across to the islands
Photo by: Tara Adcock

Rockabill Nest Census Results 2019

One of the most important numbers for any breeding seabird colony is the number of nests present that year. As the season gets closer to an end we have now complied our final nest numbers. As mentioned in previous blogs, we had an initial nest census on the 7^th to the 10^th of June and then a second on the 16^th to he 18^th of June where additional nests were added into our tallies. 

For this season, we have had:

·         69 breeding pairs of Black Guillemot.

·         167 breeding pairs of Black-Legged Kittiwakes.

·         18 Arctic Tern pairs, with 35 eggs.

·         1,833 Common Tern pairs, with 4,560 eggs.

·         1,564 Roseate Tern pairs, with 698 nesting in boxes, and 866 with open nests, and 2,807 eggs laid on the island as of the 18^th of June.

Eggs laid after the 18^th of June date are not counted towards the total as many of them would be relays of failed nests and do not represent an additional breeding pair.

A recently hatched Roseate Tern chick (left) and fully-grown Roseate Tern fledgling (right). (L. Gill, photos taken under NPWS license)

A recently hatched Common Tern chick (left) and fully-grown Common Tern fledgling (right). (L. Gill, photos taken under NPWS license)

A recently hatched Arctic Tern chick (left) and fully-grown Arctic Tern fledgling (right). (L. Gill, photos taken under NPWS license)

A Black Guillemot chick only a couple of days old (left) and fully-grown and ready to fledge (right). (E. Tiernan & B. Burke, photos taken under NPWS license)

A Kittiwake chick only a couple of days old (left) and Kittiwake having recently fledged (right). (L. Gill & B. Burke, photos taken under NPWS license)

Ringing Chicks & Catching Kittiwakes

Ringing Blitz

Boy have we been busy here on Rockabill. Lots of our chicks have become big so quickly. Most chicks that were the first to hatch have started flying around the island and some have even fledged right in front of us. During the provisional feeding studies, we saw the Roseate chicks come out of their nest boxes and test out their wings. Both Common and Roseate chicks could be seen hopping up onto rocks or nest boxes and flapping their wings to get a bit of lift. Of course, this means a lot more running around for the wardens. It has become a bit more difficult to collect our biometrics data when the birds can now fly away from us.

Common Tern fledgling stretching his wings. (Photo taken under NPWS license; E Tiernan)

Roseate Tern fledgling testing its wings with its parent watching on. (Photo taken under NPWS license; E Tiernan)

We have spotted fledglings flying around the island and practicing their plunge dives in the waters between the Rock and the Bill. It has been a treat to watch them take off, although we wardens are beginning to feel the onset of (literal) empty nest syndrome.

Now that they are getting big enough to fledge, we had to step up our ringing game. On the 1^st of July we were joined by Dr Stephen Newton and Brian Burke of BirdWatch and previous Rockabill wardens Caroline McKeon, Shane Somers and Irene Ní Shúilleabhán to help us carry out the 2019 Rockabill Ringing Blitz!

All hands on deck! Previous wardens Caroline and Shane join 2019’s wardens Lorna, Emma and Andrew to help find any tern chicks that need to be ringed. (Photo taken under NPWS license; B Burke)

Andrew and Lorna ring two Roseate chicks from the same nest while Emma records the ring numbers. (Photo taken under NPWS license; B Burke)

Roseate Tern chicks waiting to be ringed. (Photo taken under NPWS license; B Burke)

Emma tries to concentrate on recording the rings used without getting distracted (Photo taken under NPWS license; B Burke)

Roseate Tern 'BABE' (photo taken under NPWS license; L. Gill)

Every tern chick is ringed before it leaves Rockabill so we had a lot of work to do! Whilst we have been ringing all the chicks that have hatched in our study areas, this was a tiny portion of the rest of the population by comparison. We spent four days going around the island and catching as many birds as we could that were big enough to be ringed. Common and Arctic Tern chicks are ringed with the standard BTO rings while Roseate Terns are ringed with a specialised 4-digit code. In previous years this code has been made up of letters and numbers but this year our roseate rings do not have numbers. This has led to a lot of fun with naming certain chicks. To date we have gotten BABE, BABY, BALE, BAKE, BAND, BANK, BART, BARB, BEAN, BEAT, BETH, BERT and so much more.

In the coming weeks we will be carrying out follow up ringing sessions to ring any more chicks have yet to hatch.

After the ringing blitz we welcomed a new warden, Aude Boutet. Aude is a very skilled seabird ecologist from Clermont-Ferrand, France. Aude has spent the past few years working on various research projects around the world. She joins us after completing a stint researching the ecology of Common and Brunnich’s Guillemots with the British Antarctic Survey. We are very lucky to have her with us (more importantly we’re happy to have another person to talk to).

Aude enjoying watching the birds of Rockabill on the pier during low tide. (Photo taken under NPWS license; E Tiernan)

Geo locator attached to Kittiwake ring.
(Photo taken under NPWS license; E Tiernan)

Alongside monitoring our tern babies, we have also been keeping an eye on the breeding Kittiwakes and Black Guillemots. Earlier this month we recaptured and attached geo-locators to some of the adult Kittiwakes. These geo-locators will be removed next year when adults return to Rockabill and will provide valuable information on the movements of Kittiwakes between the breeding seasons. Twelve adults that were ringed on Rockabill as chicks were recaptured for this study. Of the twelve, most were between 4 and 10 years old and the oldest two were 14 and 17 years old.

Dr Stephen Newton, Aude and Andrew sailing to The Bill.
(Photo taken under NPWS license; E Tiernan)

After these geo locators were attached, it was time to start ringing the Kittiwake and Black Guillemot chicks. This took us another 4 days! The Kittiwakes and the Black Guillemots nest on both The Rock and The Bill, so that meant a couple of short boat trips.

As well as several nest boxes around the island, Black Guillemots have been nesting in small gaps in the walls, under boulders and in old, disused pipes and drains. Any small spaces they can find really!

Photo (left) Aude checks for Black Guillemot chicks in all sorts of spaces including under boulders and in the shed. (Photo taken under NPWS license; E Tiernan)

Photo (left): Emma holding a Black Guillemot chick that has just been ringed, and (right) Andrew measuring the wing of a Black Guillemot chick - note the black feathers on the white wing patch, compared to the all-white wing patch of the breeding adults. (ringing and photos under NPWS license)

The Kittiwake colonies on the other hand required some rock climbing.

 Kittiwake colonies on (top) The Rock and (bottom) The Bill 

(Photos taken under NPWS license; E Tiernan)

The climb was worth it in the end. The Kittiwake chicks may be the fluffiest chicks we have on the island.

Photo: Clutch of two Kittiwake chicks in nest. The older chick is just starting to develop its primary flight feathers (Photos taken under NPWS license; top - LA McManus; left - Gill)

Photo: Kittiwake adult and chick on a nesting ledge (Photo taken under NPWS license; L Gill)

With all that has been happening, it is hard to believe that out time on Rockabill will be coming to an end soon. As more and more nests start emptying, we now have some time to enjoy some of Rockabill’s other nature. In the recent sunny weather, we have spotted Buff-tailed bumblebees, Painted Lady and Green-veined White butterflies in the gardens.  We have also been joined by Rockabill’s resident Grey Seal family when the tide is out.

Seal family basking in the sunshine on the rocks of the Bill at low tide (Photo taken under NPWS license; E Tiernan)

That’s all the news from The Rock for now.

Emma

Common Tern flying through sunset (Photo taken under NPWS license; E Tiernan)

Blog 5 - Arctic Terns & Black Guillemots

Since our last update, we have now completed the second nest check! During this we found Arctic Tern chicks, which have hatched over the previous weeks. Some of these have a more grey-coloured down compared to Common Tern chicks. We also found hatched Black Guillemot chicks inside their nests.

Adult Arctic Tern. (Photo taken under NPWS license; A McManus)

Grey-morph Arctic Tern chick. (Photo taken under NPWS license; A. McManus)

Can you spot the Black Guillemot chick sitting in its nest hole? (photo taken under NPWS license)

 Day to day, we have been busy conducting nest checks, ringing and taking biometric data on the chicks. We take measurements of the wing length and body weight of the chicks every day to obtain growth rates, which can be compared with previous years.

Common Tern chick being weighed for our chick biometrics study. (photo taken under NPWS license; A. McManus)

Rockablog 4 – A “Tern” of Events

Life on the island has been busy of late. On Thursday the 6^th of June we had a visit from the conservation team at the EU LIFE project. They came out for a few hours to see the island and were fortunate that the same morning, we had our first Common Tern chicks hatch on the island.

Common Tern chicks in their nest . Photo taken by Lorna Gill under NPWS licence.

Following the EULIFE visit, with the help of Anita Donaghy, we conducted the first nest census, where we take a record of every breeding birds nest on the island which includes Common Terns, Arctic Terns, Roseate Terns, Black-legged Kittiwakes and Black Guillemots. We will conduct a second nest check in about a week’s time to insure no nests are missed or if any are laid in the interim. As of our first count we have 1,446 Roseate Tern pairs breeding on the island.

Emma Tiernan and Andrew McManus, both with a Common Tern resting on their heads as they conduct a nest census. Image taken by Lorna Gill under NPWS licence.

We began recording egg length and width. When the chicks hatch, we ring them, which allows us to ID them as they begin running around. We then began to record chick weight and wing length daily within our study areas so that we can measure their growth. This data allows for comparisons between years.

Nest marked with a peg for the Nest Census with a Common Tern chick and two eggs. Photo taken by Lorna Gill under NPWS licence.

During the nest census we took a trip over to the Bill. This allowed us to get a different view of the Rock than we are used to. Black Guillemot nests were found and recorded. This year no Arctic Tern nests were found on the Bill.

View of 'The Rock' taken from 'The Bill'. Photo taken by Lorna Gill under NPWS license.

 

On Saturday the 8^th myself, Andrew, Emma and Stephen were on RTE Radio One’s program ‘Country Wide’ where we were interviewed by Suzanne Campbell. The show is now available to listen to on the RTE website.  

https://www.rte.ie/radio/radioplayer/html5/#/radio1/21566549

On the 9^th of June we found our first hatched Roseate Tern chicks.  

Roseate Tern chick and egg in nest. Photo taken by Lorna Gill under NPWS license.

That is all the updates we have for now - keep an eye out soon for a blog with the results from our nest census!

- Lorna and the Rockabill Team.

Dalkey Arctic and Common Tern Colony mid - season update

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

The first Arctic Tern chick of the 2019 season on the Dalkey Islands.
Photo by Tara Adcock taken under NPWS licence.

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 12 chicks (all Arctic Terns), and 18 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. :)  

The Dalkey Islands complex. Maiden Rock on the left, Dalkey Island on the right, and Lamb Island to the right of centre.

Photo by Karen Varnham.

Arctic Tern chick.

Photo by Tara Adcock. and taken under NPWS licence.

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! 

The first ever Arctic Tern chick ringed on Dalkey Island.

Photo by Tara Adcock under NPWS licence.

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!

Arctic Terns on Dalkey Island dive bombing Stephen Newton.

Photo by Tara Adcock taken under NPWS licence.

Over the winter we carried out rat baiting on both Dalkey and Lamb Island. Rats are a serious concern when present in a seabird colony. Seabirds have evolved to nest on islands and cliff faces as these sites were traditionally free of mammalian predators. As a result, these ground nesting birds have not evolved adequate defences against potential predators such as rats (Rauzon 2007).

At the end of the baiting project, it appeared that rats had been successfully cleared from Lamb Island but had not been completely removed from Dalkey Island. However, the ability of these Tern chicks to survive thus far on Dalkey Island suggests that the rat population is significantly reduced. Fingers crossed that these little guys will fledge and survive to come back to the Dalkey Islands to breed in five years’ time!

Arctic Tern chick

Photo by Tara Adcock taken under NPWS licence.

Chris Johnson of BirdWatch Ireland assisting with the 2018/19 rat baiting project on Dalkey Island.

Photo by Tara Adcock.

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!

First colour ring of the season on the Dalkey Islands.

Photo by Tara Adcock and taken under NPWS licence.

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. 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.

Arctic Tern chick.

Photo by Tara Adcock and taken under NPWS licence.

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 and also storm surges on Maiden Rock, which has led to a reduction in the number of returning Common and Arctic Terns to the nesting grounds. 

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.

Common Terns breeding on Rockabill Island.

Photo by Brian Burke and taken under NPWS licence.

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.

Roseate Tern on Rockabill Island. These birds, unlike Common and Arctic Terns, prefer to nest under shelters such as nest boxes.

Photo by Brian Burke and taken under NPWS licence.

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.

Rockabill Island.

Photo by Brian Burke.

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.

Roseate Tern on Rockabill Island.

Photo by Brian Burke and taken under NPWS licence.

To do this, we need to either remove predators such as rats through baiting, or thwart potential predators such as gulls using a 1 m by 1 m 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. See this blog about our work to reduce predation on the islands.

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. 

Liam Gaynor recording the  Arctic Tern nest he’s just found. Grid pattern of canes to exclude passing gulls in background.

Photo by Tara Adcock. 

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.

Terns off the Rockabill island shoreline.

Photo by Brian Burke and taken under NPWS licence.

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 30^th of June, and the 14^th and 28^th 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 really enjoyed meeting you all! 

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! 

Tern Watch Event.
Photo by Tara Adcock.

Tern Watch Event.
Photo by Tara Adcock.

Guided walks on Dalkey Island.
Photo by Des Burke-Kennedy.

 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, 1^st May. Available at: https://community.rspb.org.uk/ourwork/b/natureshomemagazine/posts/everything-you-need-to-know-about-arctic-terns. (Accessed 27^th June 2019).