Wednesday, 16 September 2015

Roseate Terns on Rockabill, 2015. (Good news!!!)

We've told you all about how our breeding Black Guillemots, Kittiwakes, Oystercatchers, Arctic Terns and Common Terns did on Rockabill during the 2015 breeding season - now it's time for the pièce de résistance - how did our Roseate Terns get on? 

Roseate Tern on Rockabill. (picture taken under NPWS license)

Rockabill Island is synonymous with Roseate Terns in this part of the world. This football pitch-sized island in the Irish Sea has held Europe's largest Roseate Tern colony for quite a while, and so the future of this species in Europe is highly dependant on their fortunes on this rocky outcrop of county Dublin. In 1989 Rockabill had 180 pairs of Roseate Terns, and through a lot of hard work over the years by Birdwatch Ireland and with help from the NPWS (and RSPB in the past too), the Rockabill population reached a peak of almost 1250 pairs last year. Thats what you call successful conservation! But that was last year, what about this year....?



Breeding Pairs:
To have reached 1250 pairs last year was fantastic! The last few years numbers have hovered roughly around the 1200 mark, and we began to wonder if that was as many as Rockabill could hold, so if we got 1250 pairs again we would have been delighted. Imagine our surprise when we found 1388 Roseate Tern nests this June! That a jump of 140 pairs in a year and further cements Rockabills position as Europes most important colony. But thats not all folks......



Roseate Terns quarrel outside a nestbox on Rockabill. (picture taken under NPWS license)



The other two Roseate Tern colonies in north-west Europe are NPWS-managed Ladys Island in Wexford, and RSPB-managed Coquet Island off the Northumerland coast in England. Not only did Rockabill have a record-breaking year, but so did Ladys Island and so did Coquet! Ladys Island reached 215 pairs this year, their first time clearing the 200-mark. Not only that, but Coquet reached over 100 pairs for the first time, finishing on 111 pairs. So thats fantastic news for Roseate Terns in Britain and Ireland this year. Congratulations to everyone who has put in so much hard work over the years to get us to this point - to Dr. Steve Newton and all of the former Rockabill wardens and volunteers, to Dave Daly and Tony Murray and past wardens at Ladys Island, and to Paul Morrison and everyone on the RSPB team at Coquet Island. Fingers crossed we can push on a bit more next year!

 

Eggs:

The average number of eggs laid on Rockabill this year was a bit lower than usual, though not worryingly so. This could be down to low food availability early in the summer (all that wind and rain might have made fishing hard!), or it could be down to the age-structure of the population changing a bit as younger pairs tend to lay fewer eggs. 


Roseate Tern egg 'pipping' (picture taken under NPWS license)
Roseate Tern chick on day of hatching. (picture taken under NPWS license)

Chicks and Productivity:

Roseate Tern productivity was quite low last year, averaging less than 1 chick fledging per nest. Things were back to normal this year however, with around 1.1 chicks fleding per nest. It's productivity around this level that has allowed the Rockabill population to go from strength to strength over the last 26 years, so hopefully this bodes well for the future. Chick growth was much better than last year, indicating that a lack of food was the problem last year. While last year was a bad year, this year will help balance things out a bit, and it goes to show the importance of long-term conservation projects. One good or bad year won't make or break a project or a species - if you keep at it over time the rewards will come.

The guys at Ladys Island report having a good year, and productivity at Coquet wasn't too bad either, so it's pretty good news all around, and hopefully the future will continue to be bright for this fantastic, elegant species in the coming years!

Roseate Tern fledglings. (picture taken under NPWS license)

Roseate Tern adults and fledlgings. (picture taken under NPWS license)

Nestboxes:

Many of you have been kind enough to donate to Birdwatch Ireland's Seabird Appeal this year (see link here). One of the things we'll be using your donations for is to help pay for materials to build more Roseate Tern nestboxes. This year nearly 90% of our Roseate Tern nestboxes were occupied, the highest occupation rate we've had! Not only that, but on average the pairs in nestboxes laid more eggs and fledged 25% more chicks than the pairs not using nestboxes. Nestboxes have been truly vital to the conservation of Roseate Terns not just on Rockabill, but on all of the nearby colonies too. As the population grows, and older nestboxes get broken, its vital that we can get new nestboxes year-on-year to ensure this success continues. So a heartfelt thanks from the wardens, and the Roseate Terns, to everyone who donated! And to anyone who hasn't, there's still time..... (Click here)

Adult Roseate Tern coming out of its nestbox. (picture taken under NPWS license)

A sincere thanks too to Sean Pierce, Jim Boylan and the pupils of Balbriggan Community College for supplying us with a much-needed batch of nestboxes this year. They've been very good to us over the years, and this year supplied reached the 1000 nestbox landmark. Not only that, but this years were perhaps the most solid and well-decorated we've ever had! So a big thanks to them, and to Noel Harford, Eugene Macken and the Birdwatch Ireland Fingal branch for everything over the years! 

One of our study areas, with specifcally placed and numbered nestboxes.
Nestboxes provided by Balbriggan Community College in 2015.

Ringing:

We ringed over 1450 Roseate Tern chicks this year, though we know at least 5% of these didn't manage to fledge. A certain amount will be lost to perilous conditions on their migration to Africa, and over the next couple of years before they eventually return to Ireland and Britain to breed. This ringing programme continues to provide us with valuable data in the conservation of this species - telling us how old each bird is, where it was born/ringed, if it has previously been found breeding elsewhere etc. We look forward to the class of 2015 returning from around 2018 onwards! 

 
Adult Roseate Tern with special ring (right leg) and BTO ring (left leg). (picture taken under NPWS license)

Take a look at the graph below from the RSPB team at Coquet Island for some of the interesting information, and important from a conservation point of view,  we can get from a long-term ringing and resighting programme. In the early years, birds originally from Rockabill formed the majority of the Coquet population, but over time and with increasing numbers the proportion of Coquet-origin birds is increasing there and the population is starting to 'stand on its own' and self sustain.

 Thanks to RSPB Coquet Island for the graph. Follow their work @RSPBCoquet on twitter.




So thats it for our Roseate Terns this year. Most are now en route to Africa after what was a very successful year. After the bad news about our Arctics, and average enough performance of our Common Terns, its great to have plenty of good news about this rare, amber-listed species!
Mr. Noel Harford and Mr. Eugene Macken
Mr. Noel Harford and Mr. Eugene Macken














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