Friday, 6 September 2013

How did the Isle of May seabirds do in 2013?

Mark Newell organises the seabird research on the island for the Centre for Ecology and Hydrology and tells us how the 2013 season went::
"Well, after four months spent out on the Isle of May studying the breeding seabirds, I have now had time back on the mainland to analyse the data and find out just how well the birds performed this breeding season.  Researchers at the Centre for Ecology & Hydrology have been following the breeding seabirds on the island for over 40 years, collecting some remarkable data on the diet, survival and breeding success of six key species.

So how did the year shape up?  Well as has been previously mentioned in the blog ,2013 was a very late season with some species commencing egg laying later than they have ever done before.  A late start often means that the birds do badly and produce fewer chicks,  so we feared the worst.  We also knew that the birds had had a difficult winter and early spring. Poor weather  had taken a heavy toll on the birds with large numbers of puffins and shags found dead along the East coast. We thought that birds that survived the difficult winter would return to the island in poor condition and perhaps not produce many chicks. Our colour ringed studies of shags (birds have unique colour rings on their legs that can be read with a telescope to see whether or not birds survive and return to the island) showed that less than half the birds that had bred in 2012 returned in 2013. We have only had a higher death rate than this on two previous years in the entire 40 year study.  However, on a positive note, those shags which did survive and return to breed had an above average breeding season. 

As you may have seen on the news, over 3,500 puffins washed up dead on the east coast in March, so we started the season with some trepidation. We count all the burrows on the island to assess the puffin population every five years and luckily a count was due this year.  Somewhat surprisingly this count revealed that the population was little changed from five years ago and the return rate of individually colour ringed birds coming back to the island was more-or-less normal. So what does this mean? Well, it’s difficult to say for sure, but perhaps the distressing winter wreck of puffins observed this year may occur more often than we thought but this one was just unusual in that the birds appeared to have died inshore so that the corpses washed up on the coast. Or it could be that the population had increased since the count five years ago and that the deaths over winter just reduced the population back to its level five years ago.  Despite the late season the breeding success of the puffins was about average.

Razorbills were the biggest losers in 2013 with a below average return rate and the lowest breeding success on record following on from two poor seasons with less than half of the birds breeding managed to produce a chick.  Although guillemot breeding success was the lowest since 2008 it was only a little below average while their return rate was also normal.

The all island count of nesting kittiwakes had revealed a large drop in numbers from last year.  However, the colour ringed population revealed to us that the return rate was average.  So it looks like the birds survived the winter in good numbers but that many decided not to breed due to the poor weather delaying the start of breeding.

Fulmars were the biggest success of 2013. This species breeds later than the other seabirds on the island, not fledging their chicks until late in the summer. Fulmars returned to breed at their normal time and had their most productive season since 2002.

So, in conclusion despite the feeling of doom and gloom at the onset of the season, for most species it was a fair breeding season considering the late start.   Now for the winter fieldwork to commence...where do the shags spend the winter?  But that is a story for another day."


  1. An interesting result given all the factors involved. Hopefully Razorbills did better somewhere else.

  2. What superb news, great commentary and a lot of hard work many thanks for your update.

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