The Scottish Mute Swan Census

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1 Bird Study ISSN: (Print) (Online) Journal homepage: The Scottish Mute Swan Census C. P. Rawcliffe To cite this article: C. P. Rawcliffe (1958) The Scottish Mute Swan Census , Bird Study, 5:2, 45-55, DOI: / To link to this article: Published online: 17 Jun Submit your article to this journal Article views: 28 View related articles Citing articles: 4 View citing articles Full Terms & Conditions of access and use can be found at Download by: [ ] Date: 06 December 2017, At: 06:32

2 BIRD STUDY vol. 5, No. 2, June, 1958 EDITORIAL Readers will be glad to know that the Trust has received a generous grant from the Royal Society towards the cost of publishing Bird Study during This will enable us to publish in full some of the results of country-wide inquiries undertaken for the Trust. Without this help it would probably have been necessary to omit many of the tabular details, which are expensive to print, and to deposit them, instead, with the Trust or the Edward Grey Institute. The reports on Scottish Herons and Swans in this issue come into this category. Part of the grant has also been used in the preparation of the Irish goose distribution maps, which appeared in the March number. We are happy to take this opportunity of expressing our gratitude to the Royal Society. In future readers may be puzzled by a dimorphism in size of Bird Study. The reason is that 64 pages, which had become almost the standard length of an issue, just incur a higher postal charge now that the rates for printed matter have been increased. It will, therefore, make a considerable economy if each year's volume contains two small and two large issues. THE SCOTTISH MUTE SWAN CENSUS by C. P. RAWCLIFFE Received 27 March (A Report to The British Trust for Ornithology) SUMMARY 1. As a result of the Census in 1955, 463 nests (925 adults) and 2,121 nonbreeders were recorded. This gave a total of 3,046 Mute Swans (Cygnus olor) at the beginning of the breeding season. 2. In 1956 a special check was made in five counties but only of the breeding birds. The result suggested that the census in these counties was quite thorough. 3. The success of the two censuses is considered to be moderate. The Highlands in particular were not fully covered. The actual Swan population of Scotland was therefore probably between 3,50o and 4,000 birds. 4. There were few nests above the 500 ft. contour line and those so sited were mainly in the Border Counties. 5. The non-breeders tended to congregate in ', ds. Nearly two-thirds were in 19 herds of over 30 swans each. INTRODUCTION In Bird Study 2:46 (March 1955) it was announced by the British Trust for Ornithology that a `Census of Mute Swans' was

3 46 SWAN CENSUS 5(2) to be made in England, Wales and Scotland during Later it was decided to extend the census for another season and notice of this was given in Bird Study 3:75 (March 1956). At this stage only the three Lothian counties were considered. Subsequently, Moray and Fife were added. In 1955 the object was to count the Mute Swans (Cygnus olor) in Scotland during the breeding season, It was to be done (a) by a count of occupied nests and (b) by a count of the non-breeding birds. Also it was hoped to gather material on breeding success. In 1956 an attempt was made to count breeding pairs in certain selected counties so that a comparison could be made with It was hoped that the knowledge of nesting sites used in would be the basis of the 1956 census, allowing more time to be devoted to seeking sites previously unrecorded. ORGANISATION Experience gained in organising a similar census in East, Mid and West Lothian during 1953 and 1954 (Rawcliffe, 1954, 1955) showed the need to enlist the public's support. Publicity was given by radio and television : there was also a Scottish radio programme for children on 24 March The census was supported by the Scottish Ornithologists' Club, and an appeal was included in the S.O.C. Summer Bulletin, Leaflets in the form of off-prints from the B.T.O. appeal were sent to 90 people from whom aid could be expected. Letters or notes were printed in all national and local papers throughout Scotland and in several periodicals. In 1956 no public appeal was made and the work was done mainly by local organisers. ACKNOWLEDGEMENTS The complete list of helpers is too long to print, but grateful recognition is paid to all who so kindly assisted. Those listed below did particularly valuable field work in H. Boase, T. Boyd, Dr. J. W. Campbell, J. Cluckie, Mrs. J. B. Cowdy, W. Crawford, Dr. W. T. Eggeling, Miss W. U. Flower, Miss E. A. Garden, Dr. J. A. Gibson, I. Hall, F. D. Hamilton, K. J. M. Jackson, J. M. Kennedy, D. D. Laurie, Rev. J. Lees, L. R. Lewis, W. M. Logan Home, R. A. McBride, D. C. Macauley, I. McLean, D. MacDonald, I. R. MacLaggan, W. McWilliam, H. Mayer-Gross, J. Phillips, Dr. R. Richter, P. W. Sandeman, A. Scott-Henderson, W. Shand, A. J. Smith, R. Smith, A. J. Souter, D. Summers-Smith, A. Tewnion, P. E. Walker, R. C. Walls, G. Waterston, S. Whyte. Information was also received from Tayport Town Council ; Director of Parks, Glasgow Corporation ; Imperial Chemical Industries, Ltd., Polmont ; Carron Co., Falkirk ; Buteshire Natural History Society; Orkney Natural History Society, and the 2nd St. Ninian's Brownie Pack, Stirling. In 1956 the local organisers in Fife and Moray were J. Findlay Davidson and Dr. R. Richter respectively ; their assistance was invaluable.

4 1958 SWAN CENSUS 47 Finally I would record my debt to B. H. Grimes of the Nature Conservancy for his help with the maps. RESULTS OF THE 1955 CENSUS Broadly speaking the arrangement of the counties in Table I follows that of the Watsonian System, but no attempt has been made to sub-divide the counties ; Fife and Kinross stand separately. TABLE I POPULATION BY COUNTIES 1955 County Non- Nests Breeders County Non- Nests Breeders Dumfries 36 13o Perth Kirkcudbright Angus.. it 152 Wigtown 4 18 Kincardine Ayr Aberdeen Renfrew Banff Lanark Moray Peebles.. 2 Nairn 3 Selkirk II 3 Inverness Roxburgh Argyll Berwick 8 Io Dunbarton Io 34 East Lothian 9 34 Bute 2 14 West Lothian 7 12 Ross-shire Fife Sutherland 6 34 Kinross Caithness I Stirling.. so 42 Orkney 26 'or Midlothian Shetland I TOTAL I21 The total number of breeding birds was 925 (one cob with two pens in Nairn) so that the total Swan population recorded at the beginning of the breeding season, 1955, was 3,046 birds. Allowing for the partial cover of some counties it may be suggested that the actual minimum number of breeding birds was at least of the order of 5oo pairs and the minimum number of non-breeders of the order of 2,50o birds. The total maximum population might be 5oo higher, 4,oao birds. SUCCESS OF THE 1955 CENSUS This was moderate and might have been greater had more birdwatchers been prepared to regard the Mute Swan as a bird and not an ornament. As it is not believed that every nest was found nor every nonbreeder counted the resulting picture of Mute Swan distribution is only partially accurate. Until certain difficult areas are more thoroughly surveyed the complete pattern will not be known. There were large areas in the Central, Northern and Western Highlands from which no reports were received. Some guidance came from A. Tewnion, Aberdeen, who sent in a most helpful report on the Cairngorms and Grampians. He writes : `I have been visiting the high lochs of the Cairngorms and Grampians for 2I years now and

5 48 SWAN CENSUS 5(2 ) NO OF NESTS IS ROO >1000 HEIGHT ABOVE SEA-LEVEL (FT.) Figure i. Distribution of nests by height above the 500 ft. contour. have never seen any (Mute) Swans on them'. Again, `I am reasonably acquainted with an area covering at least Soo sq. miles and... the highest nesting swans I know are on Loch Davan' (Deeside, near Dinnet, at about 52o ft.). This and other negative reports received suggested, though admittedly without the absolute proof of observation, that there was little likelihood of the Mute Swan breeding over much of the Highlands. A great deal of the land is above the soo ft. contour and it will be noted that only 38 out of the 463 nests recorded were above this altitude. They are shown in Figure 1.

6 1958 SWAN CENSUS 49 NEST SITES BREEDING BIRDS Examination of Figure 2, on which nest sites are plotted, shows that they are often found in those areas that are more densely populated by man. Thus they are found in a belt north of the English Border and the Solway, in Ayrshire and the Lowland Plain, and along the eastern coastal plain as far north as the Dornoch Firth. Generally speaking they are absent or very scarce in the Southern Uplands, the Highlands (Central and North-western), Shetland and the Hebrides. The notable exceptions are Orkney, the Uists and Benbecula. Unfortunately the census only recorded a small fraction of the normal Swan population in N. Uist. This is the position regarding horizontal distribution : reference has been made to a possibility of a restriction in vertical distribution below the 50o ft. contour. NON-BREEDING BIRDS An interesting feature of the distribution of the Mute Swan is the presence of large numbers of non-breeding birds. These tend to congregate in herds which are usually to be found on a sheltered part of the coast, river or large loch. Two-thirds of the nonbreeders are found in 19 herds (a total of 1,399 birds). These herds are listed in Table II, and shown in Figure 3. TABLE II HERDS OF NON-BREEDING SWANS IN 1955 No. County Site Count Date 1 Dumfries R. Nith June 2 Dumfries R. Annan 5o 'Spring' 3 Ayrshire R. Ayr June 4 Lanark Hogganfield L. 31 'Spring' 5 Lanark Richmond Park 8o 'Spring' 6 E. Lothian R. Tyne 34 5 June 7 Midlothian Water of Leith 74 9 June 8 Kinross Loch Leven July 9 Stirling Carron Dam June 10 Angus Montrose Basin July 11 Aberdeen L. of Strathbeg 6o 16 May 12 Inverness L. Bee, S. Uist zoo 18 June 13 Inverness R. Ness & Beauly Firth July 14 Argyll L. Feochan August 15 Dunbarton R. Leven 32 i8 June 16 Ross-shire Dingwall June 17 Ross-shire Fearn Lodge L. 37? 18 Orkney Loch Stenness 36 Io September 19 Orkney Bay of Firth 37 Io September Those birds which would be more correctly described as `failed breeders' are grouped with the non-breeders as no evidence sufficient to distinguish between them was obtained. As far as possible

7 50 SWAN CENSUS 5(2) Figure 2. Distribution of recorded nest sites. Figures enclosed in circles indicate concentrations of nests.

8 1 958 SWAN CENSUS 51 Figure 3. Distribution of herds and areas reported without swans (shown by stippling). The signs indicating herd size are as follows: small dot, 21-4o birds; large dot, 41-6o ; triangle, 6i-8o ; circle, ; double circle, > 200.

9 52 SWAN CENSUS 5(2) I have chosen counts for June and July, because it is reasonable to assume that during those months the breeding pairs were fully occupied with their responsibilities. Much work remains to be done in charting these concentrations of non-breeding birds in Scotland. COMPARISON BETWEEN 1955 AND 1956 The revised counts for the Lothians, which were made in 1953 and 1954 (see under `Organisation') are included in Table III for comparison. TABLE III COMPARISON OF CENSUSES Year E. Lothian M. Lothian W. Lothian Fife Moray Cyg- Cyg- Cyg- Cyg- Cyg- Nests nets Nests nets Nests nets Nests nets Nests nets I o o It will be seen that the totals for 1956 are slightly down on those for 1955, 75 against 84. The summer in 1956 was wet ; in 1955 it was remarkably dry. Obviously it is difficult to say whether the weather affected both watchers and birds or only the latter. Bearing in mind that the count in 1956 represented a special effort I believe that the first count in 1955 must have been quite accurate, and that the 1956 Sample Census performed a useful purpose in establishing this. However it must be recognised that of those counties which were insufficiently covered in 1955, namely Kirkcudbright, Wigtownshire, Lanarkshire, Peebleshire, Clackmannan, Perthshire, Angus, Inverness-shire, Argyll, Ross-shire, Sutherland and Caithness, none was included in the 1956 Sample Census. SURVEY OF THE DISTRIBUTION BY COUNTIES Names in brackets are those of observers not quoted elsewhere in the text. Under the county are listed a count of the occupied nests, the number of cygnets known to have been hatched, and the nonbreeders. WEST LOWLANDS Dumfries-shire. 36 nests; 38 cygnets; 13o non-breeders. The highest nest site was at Loch Skeen near Birkhill, at 1,656 ft. R. Smith, P. Walker and J. Phillips, who did a co-operative survey, suggested that there may have been more nests in `North Dumfries before the higher ground is reached'. C. R. Dick said that there were no swans in the Langholm area of Eskdale. There is a concentration along the Rivers Nith and Annan and in the Lochmaben area. (J. Cluckie, K. M. Jackson). Kirkcudbright. 12 nests ; 29 cygnets ; 48 non-breeders. The possibility of more nests cannot be overlooked (J. Cluckie, T. Boyd).

10 1 958 SWAN CENSUS 53 Wigtownshire. 4 nests ; 16 cygnets ; 18 non-breeders. It is doubtful whether this county was fully covered. No herd was reported from Garlieston where I saw 24 Mute Swans in August On the Ardwell Estate 9 cygnets were hatched from a clutch of g, of which 7 survived (per Mrs. Brenis, Ardwell Estate). Ayrshire. 32 nests; 103 cygnets; 149 non-breeders. This county was covered by R. C. Walls whose survey showed that the swan was fairly evenly distributed throughout. Renfrewshire. 33 nests; i6 cygnets; 14 non-breeders. This county was covered by Dr. J. A. Gibson whose survey showed, as in Ayrshire, a rather even distribution. Lanarkshire. 22 nests ; 36 cygnets ; zoo non-breeders. Despite the large human population in the county, support was poor and it is to be expected that some nests were overlooked. EAST LOWLANDS Peebles-shire. 2 nests ; cygnets unknown, non-breeders unknown. Most of this county is above the 500 ft. contour line which may account for the small return, but there was probably not a complete check. Selkirkshire. a nests ; 34 cygnets ; 3 non-breeders. Most elevated breeding area in Scotland, 9 of the nests were above 50o ft. A. J. Smith wrote, `Some of the usually occupied lochs are vacant this year'. (S. Whyte.) Roxburghshire. 17 nests ; 5 cygnets ; 27 non-breeders. There were 5 nests on Loch Yetholm. I. Hall reported, `Many eggs are destroyed by gillies as the swans are considered so numerous on the Tweed as to become a nuisance to most anglers'. Berwickshire. 8 nests; 31 cygnets; 10 non-breeders. There may have been more nests (W. M. Logan Home). East Lothian. 1955: 9 nests; 26 cygnets; 34 non-breeders. 1956: 6 nests; 8 cygnets; not counted. The drop in the numbers of cygnets can be explained by my inability to check nests late in the season. Midlothian. 1955: 19 nests; 51 cygnets; 99 non-breeders. 1956: 18 nests; 44 cygnets ; 1o1 non-breeders. Nests were mainly along the Water of Leith and the Union Canal. I consider that the county was well covered in both years. West Lothian : 7 nests; 30 cygnets; 12 non-breeders. 1956: 7 nests; 28 cygnets ; not counted. As with Midlothian, I consider that the county was well covered in both years. Nests were mainly on or adjacent to the Union Canal. EAST HIGHLANDS Fife : 23 nests ; 49 cygnets ; 7 non-breeders. 1956: 23 nests ; 39 cygnets ; not counted. It would appear that the county was well covered in both years, but one cannot overlook the possibility that nests on flashes in the mining area to the west were missed (Dr. W. J. Eggeling, J. Findlay Davidson). Kinross-shire. 8 nests ; 25 cygnets ; 249 non-breeders. For Loch Leven 7 nests have been accepted (per W. Shand), but the possibility remains of 16 more ; this could not be substantiated. Some may have been repeated layings as J. M. Johnstone of Loch Leven Fisheries says some nests are robbed by anglers each year. He reported 4 or 5 broods hatched, while H. Boase reported 5 broods totalling 25 cygnets. Clackmannan. No reports were received. Stirlingshire. 10 nests ; 41 cygnets ; 42 non-breeders. Perthshire. 14 nests; 52 cygnets; 3o non-breeders (I. R. MacLaggan, H. Boase). Neither this nor the previous county was fully covered. Angus. i 1 nests ; 33 cygnets ; 152 non-breeders. The south was well covered but not the north. Only one nest was reported from the Montrose Basin (J. M. Kennedy). Kincardineshire. 4 nests; 19 cygnets; 8 non-breeders. Probably quite an accurate figure as the county was thoroughly explored by A. Scott-Henderson. Aberdeenshire. 36 nests ; 69 cygnets ; 112 non-breeders. Nests were well distributed throughout the low lying area. Although good coverage was given the possibility still remains of there having been more nests. There were 7 nests on Loch of Strathbeg (Miss E. Garden) and 7 on Loch of Skene (D. D. Laurie). (Mrs. J. B. Cowdy, Miss E. Garden, D. D. Laurie, D. C. Macaulay, W. Mac- William).

11 54 SWAN CENSUS 5(2) Banff. 2 nests ; 13 cygnets ; no non-breeders reported. Baxter and Rintoul (1928) show the Mute Swan absent in Banff, Moray and Nairn. The increase in this county has apparently been very slow. At Portsoy, from a nest with a clutch of to there were 8 cygnets hatched and reared (A. J. Souter). Moray. 1955: 26 nests ; 8o cygnets ; i6 non-breeders. 1956: 21 nests ; 67 cygnets ; not counted. In both years the county was well covered. There were two distinct concentrations of birds, one near Elgin and the other near Fochabers. Three of the 1955 sites were not used in 1956, in which year there was one new site (W. Crawford, Dr. R. Richter, A. J. Souter). Nairn. 3 nests ; 13 cygnets ; no non-breeders. The 3 nests were on Loch Flemington ; Mrs. Yalden-Knowles reported that 2 pens, each with a nest, shared 1 cob. WEST HIGHLANDS Inverness-shire (including Lewis). 24 nests ; 64 cygnets ; 33o non-breeders. Only 2 nests were reported on the mainland, at Inverness and at Loch Ruthven. There was none on Skye, Eigg, Lewis or Harris. A categorical negative was sent in for Eigg by Miss W. Flower and for Lewis and Harris by Dr. J. W. Campbell. Nests were reported from North and South Uist and Benbecula. South Uist has a particularly big concentration with a herd of ca. zoo on Loch Bee. The figures reported to the Census were : North Uist.. 6 nests, 26 cyg. 46 non-b. I nest, 3 cyg. Benbecula... to nests, so cyg. 7 nests, 27 cyg. South Uist... I I nests, 55 cyg. The 1954 and 1956 figures were supplied by R. W. J. Smith. Dr. J. W. Campbell considers that at least zo pairs normally breed in the north-west and north of N. Uist alone. No reports came from Barra, Canna, Rum, Muck, or Raasay. It was inter.. esting to learn that in November 1954 there were no Mute Swans on Loch Bee (Mr. and Mrs. G. Mills, pers. comm.). (Dr. J. W. Campbell, F. D. Hamilton, L. R. Lewis, D. Summers-Smith.) Argyll. 24 nests; 45 cygnets; 180 non-breeders. Mainly coastal nests; there was none from the hill lochs of Kintyre. There were 6 from the Inner Hebrides, 4 on Mull and 2 on Islay. None was on Colonsay and no report came from Jura or Coll. Information from Tiree came belatedly and was not precise, `they breed here as I have seen a considerable number of cygnets' and, `something over a hundred for the rest of the year' i.e. summer (I. D. MacLennan). Dunbartonshire. to nests ; 9 cygnets ; 34 non-breeders. This includes 1 nest in part of Dunbarton. Only I nest was reported from Loch Lomond. Mostly the nests were in a compact group on the small lochs to the north of Glasgow. Buteshire. 2 nests ; 8 cygnets ; 14 non-breeders. The 2 nests were on Bute. There were only 3 non-breeders on Arran, at Lochranza. No report from the Cumbraes (Bute Nat. Hist. Soc., Edin. Academy Ornithological Soc.). NORTH HIGHLANDS Ross-shire. 21 nests ; 4o cygnets ; 67 non-breeders. 13 of the nests were in the Black Isle. From Avoch the Rev. J. Lees reported the only case of colonial nesting, 5 pairs which built 6 nests within a very small compass. Sutherland. 6 nests ; 17 cygnets ; 34 non-breeders. The nests were mainly from the Dornoch Filth, Dr. I. D. Pennie wrote of the Tongue area, 'I do not think there are any in the whole of the north of Sutherland nor in the west'. (D. MacDonald). Caithness. I nest, 4 cygnets ; nil non-breeders. The nest was at Loch Heilan in the north-east. J. Gunn wrote, `Usually 3 or 4 pairs nesting in the county'. Baxter and Rintoul (1953) said, `We have no record for Caithness'. NORTH ISLES Outer Hebrides. See Inverness. Orkney. 26 nests ; 61 cygnets ; lot non-breeders. There were zo nests on Mainland of which 7 were on Loch of Stenness. The most northerly site was on North Ronaldshay (Orkney Nat. Hist. Soc.). (Royal Soc. Prot. Birds). Shetland. I bird on Unst (T. D. Dixon).

12 1958 SWAN CENSUS 55 REFERENCES BAXTER, E. V. & RINTOUL, L. J The Birds of Scotland. Vol. 2. Edinburgh & London. RAWCLIFFE, C. P Breeding of Mute Swans in the Lothians and Edinb. Bird Bull., 4 :70--I. RAWCLIFFE, C. P Breeding of Mute Swans in the Lothians 1953 and 19J4. Edinb. Bird Bull., 5:25. TERRITORIAL AND OTHER BEHAVIOUR OF THE WOODPIGEON by S. CRAMP Received 28 November 1957 SUMMARY T. The behaviour of the Woodpigeon (Columba palumbus) was studied, mainly in central London, for over eight years. Territories are established in early winter and maintained until the end of the breeding season. Ownership of territory is proclaimed by song and display flight to some extent, but mainly by the male's continued presence for long periods and by his driving off all trespassers. 2. Where the population density is high, only the trees in a territory are defended regularly, but in other cases areas of ground may also be included in the territory. 3. The process of pair formation is described and the displays which contribute to the strengthening of the pair bond. These displays, and mating, have been observed only in trees within the territory. 4. The function of territory in this species is discussed. Its main purpose appears to be to provide a safe place where the pair-strengthening displays and coition can take place without interference. It also helps to ensure sufficient nesting sites for a species which often makes many repeat attempts in one season. INTRODUCTION The extreme wariness of the Woodpigeon (Columba palumbus) in most areas makes any detailed study of its behaviour difficult. In central London, however, the task is much easier as it is both surprisingly tame and numerous. These observations are based on a continuous study of the species for many years, mainly in Holborn, Westminster and the Royal Parks. ESTABLISHMENT OF TERRITORY Colquhoun (1951) has stated that Woodpigeons appear to have little or no territorial behaviour. In fact, the Woodpigeon is a species with strong and well-developed territorial habits, and many birds in central London maintain a territory over the greater part of the year. It is convenient to start the account of the Woodpigeon's year in November, as nesting activity comes to an end in late August and early September and during the whole of October they are almost absent from the central area (see Figure 1). They then seek a change of food, feeding on acorns, seed and grain, and