Seabird numbers and breeding success in Britain and Ireland, 2005
R.A. Mavor, M. Parsons, M. Heubeck and S. Schmitt
This annual report presents the monitoring results of the Seabird Monitoring Programme in 2005 and compares these findings with previous years. The aims of the report are to draw attention to notable changes in seabird numbers or breeding success (which may merit direct conservation action or further research), to provide feedback to those who collected the data, and to place the findings for individual colonies or regions in a wider context.



Some findings of particular note in 2005 are summarised below:
Red-throated diver breeding success was close to, or above, average at the majority of sites monitored, although all nests on Coll failed due to bad weather.Seabird numbers and breeding success in Britain and Ireland 2005
Northern fulmar numbers were stable in most regions between 2004 and 2005, although there was a large increase in NE Scotland and a large decrease in NE Ireland. Productivity was similar to 2004, despite complete failure at two colonies, and thus below the long-term UK mean.
Surveys of both gannetries in the Channel Islands – Ortac and Les Etacs – found 2,547 and 4,862 AOS, respectively. Since 1999 numbers increased by 41% on Les Etacs but remained stable on Ortac.  The UK and Ireland gannet population has increased by 13% to 262,066 AOS since 1994-95.
In response to a late winter/early spring wreck great cormorant and European shag numbers decreased in many eastern regions and, for shag, also in NW Scotland.  Productivity of shags in Shetland and N and SE Scotland was particularly low, possibly due to birds failing to attain adequate breeding condition.
After 12 years of decline, the number of Arctic skua territories increased, although numbers remain low.  There was a marked increase in Shetland, where the number of great skua territories also increased, but both species decreased in Orkney. Skuas were more productive than in 2004, despite a scarcity of sandeels.
Mediterranean gulls numbered at least 224 pairs.  Breeding success was high, at 1.26 chicks fledged per pair.
Black-headed and mew gulls increased in most regions.  Some large mixed colonies of lesser black-backed and herring gull have declined substantially in recent years. At most gull colonies breeding success was low to moderate in 2005.  Once again, mink depressed the productivity of four gull species in NW and SW Scotland.
Breeding success of black-legged kittiwake was higher than in 2004, but still well below average for the UK and Ireland. Apparently low food availability early in the season resulted in late nest building at several colonies but conditions improved, allowing many birds to breed successfully.  However, low success in NW Scotland and complete failure in N Scotland was attributed to low food availability there.
Sandwich tern numbers were stable between 2004 and 2005. Birds were generally successful, with the exception of those nesting in Scotland.
Overall roseate tern numbers were stable between 2004 and 2005. Notable increases were recorded on Coquet Island and at Lady’s Island Lake. Productivity was high at the majority of colonies.
Common tern numbers increased slightly, with large increases in NE and SE Ireland, but a substantial decrease occurred in NE Scotland. Colonies adjacent to the Irish Sea were the most productive.  Food availability problems probably depressed productivity in west and north Scotland and England, with predation also a factor at some English colonies.  The number of Arctic terns in Shetland and Orkney recovered from the declines in 2004, with increases noted in most other regions. Breeding success was higher than in 2004, although only marginally so in the Northern Isles, probably due to low food availability.  Colonies in NE England and Wales were very productive.
Little tern numbers increased substantially in SE Ireland, where the most successful colony was situated. Elsewhere, breeding success in England and Wales was low, due to localised food availability problems, tidal inundation and predation, but productivity in Scotland was higher than in the previous five years.
Common guillemot and razorbill numbers in sample plots increased (or at least remained stable) in northern and eastern regions and in Wales, with decreases in NW and SW Scotland.  Whole-colony counts were broadly in line with these changes but, in addition, notable decreases occurred in NW England (razorbill only) and NE Ireland. For both species, breeding success was higher than in 2004 but still markedly below the long-term mean.  Colonies in the north of Britain were generally less successful than others.
Black guillemot numbers in Shetland and Orkney were stable between 2004 and 2005.  However, numbers have halved in Orkney since 1986, although there has been no net change in Shetland over this period.
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ISBN 978 1 86107 585 7
ISSN 0963 8083
Please cite as: R.A. Mavor, M. Parsons, M. Heubeck and S. Schmitt, (2006), Seabird numbers and breeding success in Britain and Ireland, 2005, ISBN 978 1 86107 585 7, ISSN 0963 8083