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Shiant Isles Bird Report 2008

We visited the Shiant Isles between 3 – 8 July 2008, enjoying mostly calm, sunny weather. We circled the islands by boat and counted all the Kittiwake nests on all three islands and the outlying Galtachean rocks. Two landings were made on Eilean Mhuire, the most inaccessible of the main islands. The time available for seabird work was limited, and Kittiwakes apart, the following notes are not as thorough or comprehensive as we would have liked.

Kittiwake

We counted well built nests only, with or without an attendant adult. Trace nests were ignored.

Eilean Mhuire: 525 nests were counted, with 441 of these (84%) confined to the east cliffs. Of 142 nests checked from the land on 5 July, 86 were empty and 56 had an apparently incubating adult. A further 85 had attending adults standing on the nest, but most, if not all of these were probably empty. On the west coast the colony at Bid na Faing had 43 empty nests and 16 with incubating adults. A small nearby colony had 8 attended nests, contents unknown. The south coast had a group of 6 nests, 4 of which held tight sitting adults. On the north coast there were 11 nests, most attended, but their contents unknown.

Eilean an Taighe: 4 empty nests were found, all on the south east coast of the Mianais peninsula.

Garbh Eilean: 6 nests were found, all at Tobhaichean Caola. Five were empty and unattended, one held an incubating adult.

Galta Mor: 2 unattended nests

Galta Beag: 12 nests, 6 with incubating adults and 6 unattended. The maximum group total (of 2 counts) was 549 nests, compared with 1849 nests found in 1999 (Seabird 2000) and the minimum count in 1986 of 1807 nests (Seabird Colony Register).

Kittiwake nests in 1986 1999 2008

Eilean Mhuire

1291 1798 525

Eilean an Taighe

57 0 4
Garbh Eilean 337 15 6
Galta Mor 77 36¹ 2
Galta Beag 45   12
Total 1807² 1849 549

¹Combined Galta total

²1807 min, 1920 max

The total population of 549 well built nests found over the whole island group is the lowest number since records began in 1970 (SCR). Of these, 138 (25%) were confirmed as empty, with no sign of eggs, small young or attending adults. There were only 79 nests (14%) with birds sitting tight, presumably incubating, so equivalent to the ‘apparently occupied nest’ counted in most surveys. If these samples are representative of the whole colony, then there were only 200 (36%) active nests in the islands, while the majority, 349 nests (63%), belonged to pairs that had either failed to lay or failed very early. No young were seen, and it is likely that hatching had not begun. If even recently hatched young were present, it is reasonable too suppose that some feeding by adults would have been seen, particularly on 5 July when 3 hours were spent checking nests on Eilean Mhuire. Whatever happened after our visit, breeding success in 2008 must have been very low.

Great Black-backed Gull

No counts were made on Garbh Eilean and our visit was too late to count nests, so we estimated breeding pairs based on adults apparently on territories. On Eilean Mhuire two counts suggested between 46 and 60 pairs. On 16 May 2004 S Murray (unpub) found 56 nests with eggs and 14 well built but empty nests. This, and earlier counts of AOT suggest breeding numbers are fairly stable (1986 47-60 AOT. 1995 85 AOT. SCR).

Between 8 and 12 AOT were estimated on Eilean an Taighe , many fewer than the 22-40 AOT on 16 May 2004 (S Murray). These totals should be treated cautiously. It was not the optimum time to be counting breeding gulls and the birds were very dispersed over the territories. More significant was the apparent lack of young gulls. Scottish Natural Heritage reported large numbers of recently hatched chicks on Eilean Mhuire on 17 June, whereas we found more dead than alive. Only 5 broods were seen, all about a month old, however no intensive search for broods was made and chicks could easily have been overlooked in the long grass and rushes in the centre of the island. On Eilean an Taighe no dead young were found, but only 3 broods were confirmed, all about 4-5 weeks old.

Shag

Nests were searched for along the west side of Mianais on Eilean an Taighe, nine were found compared to 46 in 1986 (SCR). There were 2 broods of two chicks, and one of one chick, all were about 10 days old. There was also a new hatched brood of 2 and two clutches of 3 eggs. Three unreachable nests had either eggs or very small young.

On Garbh Eilean a small part of the main boulderfield was checked, but only a single adult was flushed and no nest was found. Over the entire boulderfield few birds were seen standing around at any time, which would suggest a population crash rather than a major non breeding event. In 1986 and 1999 over 1000 and 246 nests respectively, were found among these boulders (SCR, Seabird 2000).

Guillemot

Two counts were made at Tobhaichean Caola on Garbh Eilean on 6 July. The average was 1289 birds, compared with 2853 in 1986 (SCR) and 2837 in 1999 (Seabird 2000), however these counts were made at the optimum time for this species. In 2008 no chicks were seen, neither were adults seen carrying fish. A small number appeared to be incubating, but most birds were very unsettled and the ledges sparsely populated. On St Kilda at the same time, the species had not begun to fledge and chicks were very obvious on the breeding ledges (S Money pers com), while on Canna numbers were low and breeding success poor. (R Swann pers com). It seems likely that breeding success on the Shiants in 2008 was also poor.

Puffin

Food loads were assessed at a dense grass slope colony on Garbh Eilean, and several hundred burrow entrances checked for dropped fish. The only fish seen being carried were small 0 group sandeels (one found was 30 mm long) but one dropped rockling (30 mm) was also collected. Loads appeared to be small. Breeding success was unknown, but no hungry chicks were heard calling from underground, and a high proportion of burrows were clearly in use.

Summary

This was too short a visit to get more than an indication of what is happening to the Shiants seabirds, but clearly the Kittiwake population was reduced, and with a 70% loss of breeding birds in a decade the outlook for them here is bleak. Great Black-backed Gull numbers appeared to be fairly stable, but they seem to have produced very few fledged young this season. Question marks also hang over Shags, and a thorough count of nests at their largest colony on Garbh Eilean is long overdue. Guillemots have likely had a very poor breeding season, with possibly some decline in overall numbers. Puffins seem to be unaffected but their breeding success is unknown. Razorbills were still present in hugely impressive numbers, especially on Garbh Eilean, but again nothing is known about breeding success. The Shiant Isles hold one of the main concentrations of seabirds in the Minch and the status of all the species breeding here is in urgent need of re-assessment.

S Murray & J A Love

 

Abbreviations Used:

AOT: Apparently Occupied Territory

SCR: Seabird Colony Register