In my view the Manx shearwater should be the official national bird of Wales! Over 50% of the world population of this species breeds here. With 316,000 pairs on Skomer and 62,000 pairs on Skokholm, Pembrokeshire alone accounts for most of that. Without doing any research I'll stick my neck out and say Manxies are the single most important bird species in Wales in terms of percentage of the world population breeding here. If I find out otherwise I'll update you! And happy to be proved wrong by anyone keen to take up the challenge!
Following rat eradication in 2000 by Wildlife Management International our Manx shearwater population exploded from 850 pairs (1998) to 4,796 pairs (2016). In order to monitor this nocturnal burrow nesting seabird we installed a series of artificial nest boxes used successfully on similar species in New Zealand.
Following several years of inspection by non breeding birds, our first two pairs laid eggs and reared young in 2016. Last year we had 7 incubating pairs of which 5 successfully fledged young while this year we had 5 incubating pairs of which 4 currently have young. The original 2 pairs from 2016 have returned to the same nest box each year and have hatched chicks for their third year in succession.
Having an easily accessible population allows us to carry out tracking work using GPS and geolocators to monitor where are birds are feeding and where they spend the winter. It also allows us to carry out more simple studies too such as productivity i.e. how successful birds are at raising young. Not an easy task for a species that is so tricky to monitor. Keeping track of weekly weight changes gives us an idea of how successful the adults are at finding food. At a time when seabirds worldwide are suffering population declines due to food shortages this is a useful monitoring tool. It allows us to compare growth weights and fledging weights year on year and, thanks to the long running projects on our neighbouring islands of Skomer and Skokholm, comparisons can be made dating back well into the last century.
It is always a huge privilege to work on this species, especially here on Ramsey where, prior to rat eradication, the scenes below would simply not have happened. Here is a little taster of our most recent weekly weigh in session
Nest box 17 - less than 2 weeks old and has put on an astonishing 115g in a week (127% increase!) - one of the pair is the same as last year but the partner is a new bird i.e. first time breeding together (both adults are out at sea by day foraging, returning at night to feed the chick)
The last one to hatch, nest box 45 - sometime in the last week, probably only in last few days given egg shell present. Adults can brood up to 7 days old but none of our birds have been present with the new chick for more than a few days. First weigh in was 53g
Box 15 and box 23 (the pioneering pairs who have bred each year since 2015) are leading the way. Typical of more experienced pairs (although you would hardly call them experts in a species that can live 50+ years) they laid earlier than novice pairs. Both hatched around 4th July and the chick from box 23 now weighs 398g; at 22 days old he/she is heavier than some adult birds. They will all need to continue this impressive early weight gain to stand any chance of returning to Ramsey to breed in future years. If they can hit a peak of 550-600g they will be doing well. The adults will abandon them from late August onwards and they will slowly whittle down their fat reserves and hopefully fledge around the 460g mark (studies on Skokholm in the 1970's showed this is to be the 'cut off weight' for fledglings being able to survive the arduous migration feat to Argentina)
It's astonishing to think the chicks in the photos above, in around 6 weeks from now, will be winging their way to the coast of Argentina, a journey that, for the quickest, can be done in 2 weeks! Even more amazing to think that in a few years time we might see them back on Ramsey, within 200m of the burrow they fledged from, looking for a nest site of their own. This is exactly what we found when we lifted the lid on box 52 last week.......
EY27530 was ringed in this very study plot as a fledgling on 7/9/12 weighing a healthy 532g. It was paired up with another non breeder who has been frequenting this box all season. Fingers crossed it is to both their liking and they produce an egg next year. It was a special moment as I held the bird to read the ring I had put on in 2012 to contemplate this individual had flown 84,000 miles on 6 return journeys to south America in that time........
I would encourage anyone to add spending a night in a Manx shearwater colony to their 'bucket list'. You can't fail to be disappointed (unless you go during the full moon! Manxies like dark nights to come ashore safely so pick new moon phases). To experience the sound of tens of thousands of birds screaming in to their colony under a star filled sky is one of life's true joys. Our neighbouring islands of Skomer and Skokholm, both managed by the Wildlife Trust of South and West Wales offer just such opportunities. To see them at sea in the evenings as they gather to come ashore I can highly recommend Thousand Islands Expeditions operating out of St Davids - click on the links for more information and enjoy the experience of Wales unofficial national bird for yourself!
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