Tuesday, 11 January 2011

Seabird Summary 2010

At last I have had time to draw together the results of all our hard work last summer monitoring the seabird population at St Abbs. Here is a summary:

Fulmar (picture left) A whole colony count of 175 Apparently Occupied Sites (AOS = a site with a bird sitting tightly on a reasonably horizontal area judged large enough to hold an egg). This is a decrease of 10% on last year (194 AOS) but similar to this and all the counts since 2004, but these counts are all below the 26-year mean (270 AOS).

Shag (picture right) A whole colony count of 157 Apparently Occupied Nests (AON = a well built nest capable of holding eggs with at least one bird in attendance). This is an increase of 14% on last year (138 AON) but similar to this and to all the counts since 2005, but these are all below the 26-year mean (256 AON). Although breeding success was not as good as last year it was exactly on the 21-year mean of 1.19 young fledged per active nest.

Herring Gull (picture left) A whole colony count of 296 AON was an increase of 64% on last year (180 AON). Some of this increase could be due to the count being carried out very early in the season, but the count was not dissimilar to those carried out over the last few years and is below the 26-year mean of 362 AON.

Kittiwake (picture right) A whole colony count of 4,744 AON was an increase of 3% on last year (4,616 AON) but less than half the 26-year mean of 11,102 AON. Although the breeding population has decreased by nearly three-quarters since 1989, the counts for the last couple of years are about the same as those from the 1950s. The breeding success of 0.48 young fledged per active nest is down on last year but a significant increase on the previous 3 years. However, still below the 24-year mean of 0.62.

Guillemot (picture left) Whole colony counts not carried out annually due to the large numbers involved, however a series of counts are made at fixed monitoring plots during the first three weeks of June and a figure for the sum of the plot means is calculated and compared with previous years. This year showed a decrease of 24% on last year but was similar to the two previous years but below the 26-year average.

Razorbill (picture right) Similar to guillemots whole colony counts not carried out annually, but counts made at fixed monitoring plots. A similar decrease to the guillemots, with numbers being 23% down on last year and below the 26-year average.

Puffin (picture left) The maximum number of birds ashore on an evening in late June are counted, this year there were just 9 which was slightly less than the last year (11) but in the same sort of region as the last 3 years.
So, all in all not really a very remarkable year, except that all the species are follwing a general downward trend from the glory years seen in the late 1980s and early 90s.

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