Tuesday, 12 August 2014

Manx Shearwaters - Wales Part Two

One of the aims of our Welsh holiday was to watch the evening spectacle of the mass return of Manx Shearwaters to their breeding burrows. The end of July and beginning of August isn’t the best time to see breeding seabirds, but Manx Shearwaters take a long time to develop and are still in the nest towards the end of August.

The more I read about these remarkable birds, the more I’m amazed by their extraordinary life.

Defra figures for 2011 suggest a UK population approaching 300,000; 79% of the world population. Half of the UK birds nest off the Pembrokeshire coast, especially at Skomer, Skokholm and Middleholm. However, as is often the case, there’s disagreement amongst experts about census methods, with one count of Skomer alone suggesting a population of 300,000.

The oldest recorded Manx was ringed as an adult, aged at least 5 years, on Copeland Island, Northern Island in July 1953. It was re trapped in July 2003, aged at least 55 years. Estimates suggest that this bird will have travelled up to at least 5 million miles in its lifetime.

Over the years there have been many arguments between lumpers and splitters about the number of distinct species or sub species of Shearwater, particularly those that are around the same size as the Manx.

We paid two visits to Strumble Head, one of the best places to see the evening spectacle from land.

One the first visit we started to observe at 20:40 and continued until 21:30. At the peak of the flypast I chose a stream of birds that were closest to the land and counted for three periods of ten seconds and found that about fifty birds were passing every ten seconds. This gives an hourly passage of 18,000 for just that one stream. There were at least two other streams further out.

Between our Strumble Head visits we viewed from the coast near Ramsey Island, but this was not as good a viewpoint. However it showed that the Manx started to appear around 16:30, albeit in two’s and three’s. So the evening passage lasts for several hours.

On our second visit to Strumble, as the passage built up at around 18:30, my beloved sat with a watch and I peered through my binoculars counting the passage over several one minute periods, again choosing a stream nearest to land.. The numbers recorded for each minute built as follows:

18:43 – 29 a minute         19:14 – 41 a minute         19:38 – 55 a minute         19:42 – 59 a minute
19:57 – 126 aminute        20:01 – 261 a minute.

My beloved often likens me to The Count from Sesame Street. Perhaps I am a bit of an anorak, but I feel that encounters such as those that we enjoyed at Strumble Head are what real bird watching is about.

Our counting didn’t lead us to conclude anything about the total number of Manx that pass Strumble Head each night, other than it’s a huge number.

We did see other seabirds - Gannets, Cormorants, Shags, Kittiwakes, Common Guillemots, Fulmars and Black Headed, Great Black Backed, Lesser BB and Herring Gulls. There were also a few Common Scoters and it was interesting not to see Eiders, which would have been prominent had we been watching in Northumberland.

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