RSPB Bird Reports

ORKNEY SEABIRDS REPORT
Summary 2009

Red-throated Diver

2009 was a good year for this species.  On Hoy, Jim & Stuart Williams located 62 aos that reared 56 chicks giving a productivity of 0.90.  The improvement in occupancy on this island means that the number of pairs there is approaching previous levels after the downturn in the early 2000s and the proportion of b/2s continues to increase. On Rousay, six pairs reared eight young giving a productivity of 1.33 while on West Mainland RSPB Reserves, 18 pairs reared 17 chicks, a productivity of 0.94.  Overall productivity from all monitored sites was therefore 0.94.

Fulmar 

Monitoring by JNCC of plots in five Mainland colonies indicated that the declines noted between 2000 and 2006 have levelled off.  Changes between 2006 and 2009 varied between +13% and –9% but none were significant.  At the three sites monitored for breeding success, however, productivity was rather poor at just 0.36 (n = 727).

At the famous colony on Eynhallow, monitored by Aberdeen University since the mid 1950s, there were 89 aos on 1st June plus five other recently failed sites.  This was the highest occupancy rate since 2003.  However, productivity was low at just 0.24, some predation of large chicks by Hooded Crows being suspected.

On the North Hill RSPB reserve on Papa Westray, there were 132 aos (only 75 in 2008) and 66 young were reared, a productivity of 0.50 while on Rousay 66 aos in monitoring plots on the west coast produced 52 fledged chicks, productivity 0.79.

On Hoy, productivity was especially poor, 86 aos at the Old Man producing only 25 chicks (0.17) and 82 aos at the Bay of Creekland rearing only 15 young (0.18).

North Ronaldsay and Swona, however, had good seasons for this species although exact productivity figures could not be calculated.

There was thus a very mixed picture for Fulmars from around Orkney with no apparent easy explanation for this variation.

Gannet

The long-standing colony on Sule Stack was not counted but the two new colonies established in 2003 go from strength to strength.

On nearby Sule Skerry, there were 1000 aon, the Sule Skerry Ringing Group ringing over 300 chicks and colour-ringing 100 adults.  14 of the adults handled had already been ringed on Sule Stack in 2003 and 2007, confirming the origins of birds in the colony.  At Noup Head, Westray, the colony increased to 499 aon and at least 166 chicks reached near-fledging.

Cormorant

On Boray Holm, 90 aon were counted and the colony had an apparently productive season.

The Hen of Gairsay colony was deserted this year, the birds perhaps having moved to Boray Holm or, perhaps more likely, to Little Linga, where 60 adults were counted from the ferry on 1st July.  It is the first time that this island is known to have been used by this species.  On the Little Green Holm there were 39 aon and it seemed to be a very late season there, 32 of 39 nests still having eggs or naked chicks on 2nd August.

Shag

On Sule Skerry, 200 chicks were ringed, a marked improvement on 2007 when only four pairs were present.  This was, however, still well down on the 800-1200 chicks ringed in the late ‘80s/early ‘90s.  Elsewhere, the only good productivity data came from Papa Westray where five aon produced 11 young, 2.2 young per pair.  Anecdotally, other sites such as Shapinsay, South Walls, Muckle Skerry and Swona all had good numbers of young.

Arctic Skua

This species had a much more successful season than of late but there were few really good productivity data.  The North Hill of Papa Westray held 66 aot (only 40 in 2008) and produced 30 chicks to fledging, productivity 0.45.  Seven monitored aot on Hoy produced 11 chicks, productivity 1.57.  Fledged or almost-fledged chicks were seen in almost all known breeding areas and anecdotal evidence suggested at least a moderately good breeding season throughout the isles, albeit from a much reduced base.

Great Skua

The most closely monitored (sub) colony is at Stourdale on Hoy.  Chris Booth located 50 aot, only 44 having been found in 2008.  However, breeding success was poor, only 12 aot remaining occupied by 20th July and only six single chicks being located, there being no sign of young in the other six territories.  Even if all these chicks fledged, the maximum productivity could only be 0.12.

Elsewhere on Hoy, Andrew Upton monitored 32 aot in the Shell Hill and Mill Burn area; 17 chicks fledged, a productivity of 0.53.  On Papay, there were 28 aot (20 in 2008) and they fledged 30 young, a productivity of 1.07.

It is unclear what is happening to our Bonxie population as it is some time since the colony on Hoy, with over 2000 pairs the second largest in Britain after Foula, has been censussed.  There is a pressing need for such a count to be undertaken.

Black-headed Gull

The colony at Mill Dam, Shapinsay, often the largest in Orkney, continued to decline with only 130 adults present and all nests eventually failing.  Elsewhere, however, the species did well with considerable numbers of young being fledged although there were few hard data.  On Egilsay, 34 pairs reared 33 chicks (0.97) per pair, the best year for some time at this site.  The largest colony this summer was at the delightfully named Mires of Whip on Sanday where 600 adults were counted but there was no productivity data.

Common Gull

This species experienced a good season with lots of young being reared in many colonies although detailed breeding success monitoring is not usually carried out on this species.

Success was not universal, however, with a colony of 160 adults at Stines Moss in the Stenness hills failing totally, perhaps as a result of predation by larger gulls species from a nearby colony.  Similarly, two colonies on Hoy fared badly with that at Whaness fledging only three chicks and that at Sandy Loch failing altogether.

Lesser Black-backed Gull

There was no productivity information for this species.

Herring Gull

The only productivity data came from Burray Ness where, on 16th June, Bob Adam located 54 nests and ringed 46 chicks.

Great Black-backed Gull

The once enormous colony at the Burn of Forse on Hoy, that used to have over 1000 pairs, held only about 40 adults in July.  Similarly, the Stourdale colony, once 600 pairs-strong, had only 16 aon.  These latter birds did, however, produce 10 chicks, productivity 0.63.

The biggest colony was on Copinsay where there were an estimated 250 pairs.  At the Mull Head, Deerness, there appeared to be little change from 2008 with 39 chicks being ringed on 24th June.

Kittiwake

The decline of this species continues almost unabated although this year at least some young were reared and, indeed, some colonies had reasonable success.

Monitored plots at five Mainland colonies showed the continuing downward trend that has been apparent since 1988 with declines since 2006 ranging from 31% to 86%.  Whole colony counts were also carried out at these sites and at Row Head, Costa Head, Mull Head and Gultak numbers fell in line with the plots.  However, at Marwick Head, the whole colony decline was only 7.6% compared to 31.3% on the plot.  These five colonies are now holding only 30% of the nests that they held in 1986 or 22% of those that they held in the peak year of 1991.

Breeding success at Mull Head was zero but at the other four sites varied from 0.57 to 0.66.  In total, 335 monitored nests produced 212 young, productivity 0.63.

On Papa Westray, only 10 pairs nested in the Fowl Craig monitoring plots and no young were reared.

On Rousay, a boat-based survey of the SSSI cliffs gave a total of 882 aon compared to the 4900 pairs counted in the 1990s.  12 monitoring plots have been followed on these cliffs and this year only one of the 12 was occupied; 11 nests there reared six chicks, productivity 0.55.  As recently as 2007, there were 73 aon that reared 35 chicks.

On Sule Skerry, a better year was experienced than on the last visit in 2007 but numbers ringed were 75% down on the heyday years.

Common Tern

The main colony on the old wooden pier at Lyness held up to 160 adults (11th June) and fledged a minimum of 14 chicks (15th July).

Arctic Tern

It was a much better year for this species but it was far from being a total success.

On North Ronaldsay, 373 pairs nested but the majority failed.  A late colony of 30-40 pairs at Nouster did, however, rear young.

On Papa Westray, 667 pairs on the North Hill Reserve reared 227 chicks (productivity 0.34), the first to fledge here since 2002.  Elsewhere on the island and the neighbouring Holm there were 992 adults but no breeding success figures could be obtained.

On neighbouring Westray, there were at least 1000 adults; no productivity data were obtained but young were certainly reared in some colonies.

On Sanday, the colony at the Start held up to 400 adults in two sub-colonies; at least 100 pairs nested and produced c.150 young.  However, a colony of at least 50 pairs found by Bill Badger at Overbister failed perhaps as a result of disturbance.

On Auskerry, there were two sub-colonies.  One in the north of the island comprised early-arriving birds and fledged ‘lots’ of chicks while the other, near the lighthouse, established itself much later but still fledged young.

On Egilsay, 48 pairs bred.  However, one colony was trampled by sheep at the egg stage and the other was heavily predated; only six chicks fledged.

On Gairsay, there were colonies of 460 and 220 adults with chicks fledging from both.

In the West Mainland, a colony at the traditional Yesnaby site held 80 adults but deserted, possibly as a result of disturbance from a motor-cross event.  It was thought that it was these birds that moved a short distance north to Hyval where there were 65 on 4th July.  However, this colony failed too.  The well-known and very viewable colony on the rock stacks at Skiba Geo, Birsay held 120 adults on 8th July by which time some young had already fledged; 72 fledglings and chicks were counted here on 16th July.

In the East Mainland, a colony at Stembister held 450 adults on 7th June but a visit at the beginning of July revealed only one fledged chick, the rest of the colony having apparently failed.  On nearby Copinsay, there was much smaller colony (62 aon) than in 2008 but this year at least some young are known to have fledged.

On Glims Holm, the main colony held 300 adults on 8th June and 26 chicks were ringed on 26th June but the colony was deserted by 10th July.  This colony was in a very open site and very vulnerable to predation.

On Burray, at the Hass, there were 500 adults on 18th June and some chicks were three-quarters grown; 103 chicks were ringed.  Fledged young were seen on 3rd July and many more were near fledging, a further 103 chicks being ringed.  On Hunda, there was a similarly productive picture with 350 adults on 18th June; 57 chicks were ringed on 28th June and a further 85 on 3rd July; many fledged and near-fledged chicks were seen.

On Flotta on 23rd June, there were colonies of 80, 150 and 120 adults with some chicks and lots of eggs.  Swona was visited by the Orkney Ringing Group on 5th July when 600 adults were present in three sub-colonies; 76 chicks were ringed and the colony was still ongoing on 31st July. On the Muckle Skerry, visited on the same day, there were 400 adults and 31 chicks were ringed.  On Hoy, a colony in the south of the island held 163 adults on 15th July and 40 fledged chicks were seen; other colonies on the island fledged small numbers of young while others failed.

Little Tern

Although up to 13 adults were present at the regular south isles site, only four pairs are believed to have bred and no young are thought to have been reared.

Guillemot

Numbers in the five JNCC monitored plots on the Mainland have been declining since 2000.  The 2006-2009 declines varied between 13% and 20% and were all statistically significant.  Numbers at all the colonies (except Mull Head) are now at their lowest since monitoring began.

However, breeding success was better this year than for some time.  At Marwick Head, 116 aon produced 46 young (productivity 0.45) and at Mull Head, 94 aon reared 48 young (0.51).  Interesting observations by Roddy Mavor indicated that Marwick was one-two weeks behind Mull in fledging even though chicks appeared to be at the same stage, this perhaps being the result of poorer feeding at the former site.

On Papa Westray, 281 aos were counted in the monitored plots and 152 chicks fledged, a productivity of 0.54. 

On Sule Skerry, breeding success was noted as being much better than in 2007, there being much less predation as the increased number of adults present gave more cohesion to the colony and greater protection from predators.  However, the numbers ringed were still only half the average July totals of the 1990s.

Razorbill

At the five monitored colonies on the Mainland, numbers fell in all plots.  Marwick had been declining since 2000, Row and Gultak since 2003 but at Costa and Mull Head, numbers had actually been increasing until this year.  The 2006-2009 declines varied from –5% to –34% but only at Costa (-34%) and at Gultak (-30%) were they significant.

On Papa Westray there were 59 aos in monitored lots from which 11 young fledged, a productivity of only 0.19.  Elsewhere, anecdotal evidence also suggested that breeding success had not been as good as for Guillemot.

Black Guillemot

The April count around North Ronaldsay gave a total of 549 birds.  Good breeding success was noted in the south-western part of the island but it was much poorer elsewhere.

A count around the North Hill, Papa Westray was undertaken on 13th May and revealed 234 adults compared to 205 in 2008.

Puffin

On Sule Skerry, possibly the biggest colony in Britain at present, there was no complete census but the impression was gained that there were perhaps fewer birds than in the mid-1990s.  Over 1000 fledging chicks were ringed and they appeared to be fully grown and well fed compared to the early fledging of chicks in poor condition that was noted in 2007.  More than 8000 adults were ringed and c.3000 recaptured.

Elsewhere, the species seemed to have a good season, and many more birds than usual were noted, for example, at the well-visited Castle o’ Burrian site on Westray and at Fowl Craig on Papa Westray.

Acknowledgements

A brief report such as this disguises the immense amount of effort that goes into collecting the data that are summarised here. Grateful thanks for all their efforts go to:

Bill Badger; Jez Blackburn and other members of Sule Skerry Ringing Group; Chris Booth; Mike Cockram; Bob Adam & Colin Corse (and other members of Orkney Ringing Group); Keith Fairclough; Tim Dean (and other staff of SNH); Lorna Dow, Paul Hollinrake, Alan Leitch, Andy Knight, Barry & Rebecca O’Dowd, Lee Shields, Caroline Thompson and Tim Wootton (all RSPB); Dennis Paice & Roddy Mavor (JNCC); Alison Duncan and other staff of North Ronaldsay Bird Observatory; Paul Thompson and students of Aberdeen University; Andrew Upton; Jim & Stuart Williams.

 

Eric Meek, RSPB Scotland Area Manager

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