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Vol. 18 No. 2 ISSNCIm...... Scottish Birds The Journal of the Scottish Ornithologists' Club Editor: Anne-Marie Smout Assisted by: Professor David Jenkins. Dr J B Nelson and Professor P J B Slater Business Editor: The Secretary. S.O.e.. 21 Regent Terrace. Edinburgh EH7 5BT. Scottish Birds, the official journal of the Scottish Ornithologists' Club. publishes original material relating to ornithology in Scotland. Papers and notes should be sent to The Editor. Scottish Birds. 21 Regent Terrace. Edinburgh EH7 5BT. One issue of Scottish Birds is published each year. in December. Scottish Birds is issued free to members of the Scottish Ornithologists' Club. who also receive the quarterly newsletter Scottish Bird News and the annual Scottish Bird Report. These are available to non-members at a subscription rate (1991) of £30. The Scottish Ornithologists' Club was formed in 1936 to encourage all aspects of ornithology in Scotland. It has local branches which meet in Aberdeen. Ayr. the Borders, Dumfries. Dundee. Edinburgh. Glasgow. Inverness. New Galloway. Orkney. St Andrews. Stirling. Stranraer and Thurso. each with its own programme of field meetings and winter lectures. The Waterston Library at the Club's headquarters at 21 Regent Terrace. Edinburgh EH7 5BT is one of the most comprehensive ornithological libraries in Scotland. and is available for reference during office hours (Monday to Friday. 9am to 5pm). A comprehensive stock of Scottish local bird reports is held at the headquarters and may be purchased by mail order. SOC annual membership subscription rates Adult ................................................................................................... £12.00 Junior (under 18. or student under 25) ......................................................... £5.00 Family (husband & wife. & children under 18) .............. .. ................. .... ........ £18.00 Life Individual ........................ £240.00 Family ... ...... ........ ................. £360.00 Pensioner Individual ................... £7 .00 Family .. ........... ....................... £10.00 Published by the Scottish Ornithologists' Club, 21 Regent Terrace, Edinburgh EH7 5BT. Printed by Alexander Ritchie & Son Ltd., 163 Bonnington Road. Edinburgh EH6 5RE. Scottish Birds (1991) 16: 53-56 53 Scottish Snow Bunting numbers in summer 1970-87 A. W ATSON AND R. SMITH More summering Snow Buntings were recorded in Scotland in 1970-87 than in previous decades. Birds are known to have reared young on eight hills in the Cairngorms and east Mounth, on 12 in Inverness-shire and Ross-shire, and two in Sutherland. Adult sightings were made on 9 other hills in the Cairngorms and east Mounth, and on 31 other hills west and north of the Cairnporms. C~ck numbers found on a regularly studied area In the Cairngorms fluctuated over the study period but were higher than previous counts there. Introduction reports, which we followed up by requesting The Snow Bunting Plectrophenax nivalis is further details from regional recorders and one of Britain's rarest regularly breeding original observers. Only our own birds (Sharrock 1976), and in the Scottish observations in the central Cairngorms were Highlands is at a southern margin of its made regularly, thus allowing comparisons largely arctic breeding distribution. between years. Elsewhere, records were Nethersole-Thompson (1966) summarized sporadic, and on many hills the bird's his own and most other Scottish summer presence was recorded in only one summer. records up to the early 19605, and later A few wintering birds stay on Scottish (1976) some notes by a number of other hills until early May (R.S., unpublished data observers. Thorn (1986) briefly mentioned from marked birds). We have therefore only some observations from all of Scotland. included observations of single adults or Milsom & Watson (1984) summarized their pairs after the middle of May as summering records from part of the central Cairngorms birds. Nearly all observations were in June­ in 1971-77, and A.W. studied a larger area August. there in 1970-86. In 1987, R.S., A.W. and To protect the birds we give no precise others increased the effort there, and R.S. locations. A "hill" is a separate, distinct began an intensive study with marked birds hill, not a subsidiary top or summit; above in 1988. This paper summarizes the 3000 ft (914 m), this means a "Munro" as frequency and distribution of breeding and in Donaldson (1984). Some hills, where an summering records for Scotland in 1970-87. adult or pair was seen in summer, had only It also considers the evidence for changes one known site each such as a corrie or part in numbers since previous work and during of a plateau. On other hills, Snow Buntings 1970-87 . were seen in two or more such sites per hill, often in the same year. In this sense, the Methods term "site" is in anyone summer effectively equivalent to a territory. The records came from: - a) our own observations, mostly in the Cairngorms and east Mounth, b) unpublished notes for all Results of Scotland, made by various observers and Summering birds were seen at 62 hills and given to A.W., and c) published annual bird 104 sites during 1970-87, and fledged young 54 A. Watson and R. Smith S8 16 (2) at 35% and 390/0 of these respectively (Table number of cocks (Fig. I). Cocks may have I). There were also many records of nests been in excess, but the far less conspicuous and of adults carrying food, but adding hens are easily overlooked unless these to Table 1 does not increase the figures observations are intensive. there. Many hills had only one or two recorded sites each, occupation of which Discussion was found only sporadically. This does not The figures of 62 hills and 104 sites where mean that occupation was sporadic, as we summering birds were found in 1970-87 are have no reports of 'nil observations' except much higher than the figures in previous for our own data from the Caimgorms estimates of Scottish breeding numbers (without these one cannot say whether a lack (Nethersole-Thompson 1966, Thorn 1986, of records for a site is due to observers going 6-21 pairs Nature Conservancy Council there and finding no birds, or to no 1989). If the maximum percentage observers going there). occupancy of sites (79%) in the intensive On the fairly intensively covered area area in the central Cairngorms (Fig. 1) is in the central Caimgorms, numbers extrapolated to all of Scotland, up to 82 sites fluctuated considerably from year to year would be occupied in peak years. However, (Fig. 1). When the number of cocks there hills with only one or two known sites may in 1971-87 was compared with year, there be marginal, with lower occupancy than the was no significant trend. Annual cock Cairngorms, so the figure of 82 is probably numbers seen in 1970-87 there exceeded an overestimate. On the other hand, this those recorded in 1929-66 in the whole effect would be counter-acted by birds being Caimgorms massif (Nethersole-Thompson on hills or parts of hills not visited by bird 1966). watchers whose reports on sightings came The number of hens seen in the central to us. The records are therefore far too Caimgorms in 1971-87 was far less than the incomplete to estimate breeding numbers TABLE 1. Number of hills and sites where adult Snow Buntings were recorded summering (feeding fledged young in summer), and maximum number of cocks recorded on any hill in anyone summer during 1970-87, (a) west and north of the Cairngorms, and (b) in the Cairngorms and east Mounth. Number of Maximum no. hills where summering sites where summering of cocks (fledging) (fledging) (a) I nverness-sh i re 14 (6) 22 (7) 3 Inverness-Ross march 3 (2) 3 (2) 1 Ross 11 (4) 11 (4) 2 Sutherland 10 (2) 10 (2) 1 Shetland 3 (0) 3 (0) 1 West Perth 2 (0) 2 (0) 1 Argyll 2 (0) 2 (0) 1 (b) Cairngorms west 6 (4) 21 (8) 6 central 4 (2) 19 (15) 13 east 1 (1) 5 (2) 2 East Mounth 6 (1) 6 (1) 1 Total 62 (22) 104 (41) 1991 Snow Bunting numbers in summer 55 14 of Dotterel Charadrius morinellus in Scotland in recent years (Watson & Rae 1987). 12 Nethersole-Thompson (1966) gave details of earlier records back into the last century. This indicated more records in 10 decades around the turn of the century than in the 1920s and 1930s. His own observations in the Cairngorms showed fewer records in the 1930s than in the 1940s­ 8 early 1960s. He suggested (1966, 1976) that ..c:: these differences related to climatic :::l o variation, with low numbers during warmer o 6 periods such as the 1930s, but he did not expand on which climatic factors were E :::l involved, apart from mentioning snow E 4 cover. The possibility that the number of c:: cocks on part of the central Cairngorms in ~ 1971-77 was related to snow cover there at the beginning of June has been rejected 2 (Milsom & Watson 1984); if anything, the association was negative. However, the statistical drawbacks of small sample size o due to the small number of birds would make any analysis of doubtful reliability. Year A human cause of changes in numbers (e.g. Watson 1979) cannot be ruled out. A FIGURE 1. possible confounding factor is artificially increased"food in summer (scraps from hill walkers) and in winter (scraps and reseeded accurately, but the number of sites occupied areas at ski centres, upland car parks and may have been up to 50 in some years. roads, scraps from hill walkers, and feeds The higher numbers seen in the central left outdoors for deer, sheep and cattle). The Cairngorms since 1970 have led to the frequency of predators may also be lower, suggestion that numbers in all of Scotland due to their avoidance of walkers and skiers.

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