Marsh Warbler - 2009 - first for Pembrokeshire

I was walking down South Valley, Skomer, about 10ish this morning (2nd November) when a Blackcap flew up followed by a second bird that I thought was going to be a Garden Warbler, but it was an acro!

I watched it off & on, more off than on, for an hour or so & got quite a few not massively helpful photos & was leaning towards it being a Marsh Warbler.

Looking at the photos on the computer & doing some reading up I'm still not 100% sure, partly because it's been suggested any very late acro isn't going to be a Marsh Warbler and partly because I'm not sure if the photos undisputably show the wing formula.

The vast majority of Marsh Warblers have the 2nd primary longer than the 4th - in the photos of this bird primary 2 looks about the same, possibly longer in one photo, possibly shorter in another depending on the angle - there is one photo of the closed wing slightly from underneath that possibly shows the 2nd primary clearly longer than the 4th, if the dark mark is the tip of the 2nd primary! So not sure on that.

If you draw a line across from where the emargination ends on the 3rd primary of a Marsh Warbler it should line up with tip of about the 7th primary, on Reed Warbler it should fall level with about the 10th primary - all the photos seem to show it being about the 7th or 8th primary depending on what angle you draw the line at. Bit happier about this feature.

Bill looks stout in most of the photos, more pointy in a couple - leaning towards Marsh on this. Obvious pale tips to the primaries? - apparently not a brilliant feature in the autumn, this bird has got pale tips but I'm not convinced anything above and beyond a Reed Warbler. The claws look very pro-Marsh to me, fairly plain, lacking obvious contrast between the dark upperside and yellowish underside.

I've seen quite a few 'interesting' looking autumn acros on the east coast that just looked and sounded like Reed Warblers to me but this bird never looked like a Reed Warbler & it was making a low 'chuck' call which isn't a call I would associate with a Reed Warbler.

Dave Boyle

The only previous claims were on Skomer on 23rd Sept 1993 and on Skokholm 21-22nd September 1995.  Both were NOT ACCEPTED by the Welsh Records Panel. The above is therefore the first record for the county.

Seabird research - 2012 Skomer

Sheffield University News Release - 26 June 2012

Scientist spends 40 years studying island’s seabirds

See Video here

A bird expert at the University of Sheffield has spent 40 years studying seabirds on an island off the UK in one of the longest running investigations of its kind.

Professor Tim Birkhead, of the University’s Department of Animal and Plant Sciences, first visited Skomer Island - situated off the cost of west Wales - in 1972 and since then he has returned every summer, gaining invaluable information about guillemots.

He will visit the island again on June 21 2012 for 10 days, marking his 40th breeding season studying the guillemots, conducting an annual census and ringing the birds to see how old they are when they start to breed and how long they live.

Professor Birkhead said: “It has been an invaluable investigation, for example it is clear that climate change has had a huge effect on the guillemots as they now breed two weeks earlier than they did in the 1970s. We also know a huge amount more about guillemot biology than we did 40 years ago, and we can use changes in guillemot numbers to tell us what is happening in the seas surrounding the island.

“Long term studies like this are few and far between but remain vital for understanding changes taking place in the environment. It’s been a constant challenge both to secure funding and to carry out the work itself as the birds breed on the sea battered cliffs of a remote island.”

Home to about half a million seabirds, including the guillemots, razorbills and puffins, uninhabited Skomer Island is a natural nature reserve, specially protected and a site of scientific importance.

Technological advances throughout the four decades have enabled Professor Birkhead to gain even more information about the birds.

He added: “Using new tracking technologies, like GPS and geolocators, we now have a very complete picture of where guillemots go to forage. During the breeding season they forage within about 60 km of Skomer in the south Irish Sea, but in winter they travel huge distances moving between the Bay of Biscay and the far north of Scotland.

“We also know from guillemots research elsewhere around the UK coast that Skomer is extremely fortunate to be enjoying an increasing population. At other colonies the lack of fish has caused massive breeding failures, reduced survival and decreasing populations.”

During the early stages of the pioneering study, Professor Birkhead came up with innovative ways to overcome the many technical challenges he faced. In 1972 no one knew how to conduct a census of guillemots as it had never been tried before.

The second task was to determine how many chicks were produced each year and whether it was enough.

In 1972 when Professor Birkhead began his studies the guillemot population breeding on Skomer was just 2,000 individuals, yet pictures of the island thirty years earlier showed that there were around 100,000 guillemots then. In 2011 numbers were up to 20,000 individuals.
 

Guillemots on the island

By marking birds individually with colour rings Professor Birkhead was able to measure their breeding success, see how old they are when they first start to breed and see how long the birds live.

Adult guillemots have an annual survival rate of 95 per cent and equivalent of an average life span of 25 years. On average about 80 per cent of guillemot pairs successfully rear a chick to fledging, and of these around half survive to breeding age, which is seven years old. This high survival of immature birds more than off-sets the natural mortality of the adult birds, so the population has increased.

Professor Tim Birkhead

Seabird mortality & oil spills - 2005 research

News release from Sheffield University - 25 October 2005

Oil spills and climate change double the mortality rate of British seabirds

New research from the University of Sheffield has shown that major oil spills and a changing climate have had a far greater impact on populations of British sea birds than was previously thought.

A team led by Professor Tim Birkhead from the Department of Animal and Plant Sciences at the University of Sheffield, has shown for the first time that major oil spills double the mortality rate of adult guillemots in Britain, even though the pollution occurs hundred of miles from the birds' breeding grounds. The research, which is to be published in the November issue of Ecology Letters also shows a direct link between a warmer climate in the North Atlantic and a higher mortality rate among British guillemots.

Professor Birkhead's long-term guillemot study has been carried out on Skomer Island, Wales, since 1972. The length of the ongoing study has allowed the research team to study the effects of a number of serious winter oil spills on the guillemot population. Their findings show that highly publicised oil spills in southern Europe, such as the Prestige oil tanker disaster off the coast of Galicia, Spain, in November 2002, have far-reaching consequences on seabirds breeding far from the scene of the initial pollution.

The study has also found that consistently high values of the North Atlantic Oscillation (NAO) index (an annual measure of a large scale climatic phenomenon affecting winds, temperature and rainfall) for the past 30 years, has had a negative effect on the guillemot population of Skomer Island.

Professor Tim Birkhead of the University of Sheffield said: "Prior to our investigation of the guillemot population of Skomer Island, the impact of oil pollution on seabird mortality rates at a particular colony was difficult to quantify as oil spills usually occur in wintering areas where birds from many different colonies may be distributed over a wide area. However, our long-term monitoring of individually marked birds on Skomer Island has enabled us to see a direct correlation between major oil pollution events and a twofold increase in winter mortality rates of common guillemots.

"Our research has also shown that the NAO index has had a significant effect on the guillemot population. The consistently high values of this climatic phenomenon for the past 30 years may be due to human-induced global climate change. If this is the case, it would mean that seabirds are vulnerable to human activities on two counts: oil pollution from tanker spills and changes to the ecosystem as measured by the NAO index and caused by global climate change from man's burning of fossil fuels."

Puffin - 2011 reserach - migration strategy

Individual Atlantic puffins 'scout out' their own migration routes rather than relying on genetic 'programming' or learning routes from a parent, a new study suggests.

The evidence comes from research by a team from Oxford University and Microsoft Research Cambridge which used BAS geolocater tags to track the migration movements of 18 birds: with 8 of these birds being tracked for two consecutive years.

The study found that the birds followed a wide range of different migration routes (suggesting their movements were not genetically predetermined) but that they were not merely random as the same bird followed a similar route each year. Because young puffins leave colonies at night, alone, long before their parents, the idea that they might learn a route directly from others also seems extremely unlikely.

'We think it's likely that, before they start breeding, young puffins explore the resources the ocean has to offer and come up with their own individual, often radically different, migration routes,' said Professor Tim Guilford of Oxford University's Department of Zoology, who co-led the study. 'This tendency to explore may enable them to develop a route which exploits all the best food sources in a particular area wherever these might happen to be.'

The team believe this kind of 'scouting' for good migration routes could also be used by many other species of birds, especially seabirds -- which can choose to stop and feed anywhere on the ocean during their migration.

The full article can be found here

Guilford T, Freeman R, Boyle D, Dean B, Kirk H, et al. (2011) A Dispersive Migration in the Atlantic Puffin and Its Implications for Migratory Navigation. PLoS ONE 6(7): e21336. doi:10.1371/journal.pone.0021336

Manx Shearwater - 1894

Species account from M Mathew, 1894, "The Birds of Pembrokeshire and its islands"

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