VOL. LI1 MAY No. s 1959

BRITISH BIRDS

SURVEY OF HOUSE MARTIN COLONIES IN EAST LANCASHIRE By L. E. BOULDIN INTRODUCTION IN THE SUMMER of 1958, the East Lancashire Ornithologists' Club carried out a local survey of the nesting-sites of the House Martin (Delichon urbica), with a view to ascertaining- their distribution and the factors controlling it. The area chosen for study was that bounded by a circle of 15 miles radius from the centre of Accrington (Fig. 1). This area intrudes into Yorkshire as far as Slaidburn and Paythorne in the north, and to Hebden Bridge in the east. Running roughly south­ west to north-east across the centre of it is the industrial belt Blackburn/Accrington/Burnley/Nelson/Colne, which lies mainly in the valley of the River Calder. To the north-west of Nelson and Burnley the mass of Pendle Hill (1,831ft.) obtrudes between this industrial belt and the Ribble Valley (Longridge/Ribchester/ Clitheroe/Gisburn/Skipton), which in turn gives on to rising moor­ land (LongridgeFell/Easington Fell) and the Hodder Valley around Slaidburn in the north. Much of the eastern and southern parts encroach on high and bleak moorland (Stanbury Moor/Wadsworth Moor/ Heptonstall Moor) in the east and the so-called Forest of Rossendale in the south. The whole is a largely moorland zone embracing a central industrial belt, with minor townships in the north and south, and intersected by a number of prominent river valleys with their accompanying roads, railways and built-up areas. The Leeds and Liverpool Canal also runs diagonally across the area through the industrial belt. Woodland is scarce, but there are some 40 reservoirs, the majority south of the industrial belt. The whole area embraces some 452,000 acres in north-east Lancashire and the overspill into Yorkshire. Individual returns showed that the part east of the Clitheroe/ Whalley environs and north of Ramsbottom in the south had been well covered, but unfortunately little information was received for

141 142 BRITISH BIRDS [VOL. LII

FIG. I—SURVEY OF HOUSE MARTINS (Delichon urbica): MAP OF TOWNS AND OTHER PLACE-NAMES IN TEXT The dotted line shows the boundary of the area of the survey: a circle of 15 miles radius from the centre of Accrington, Lancashire. Other lines are main roads. the western half of the area, records of only six sites coming to hand. Thus the value of this survey has been limited by lack of full coverage over the whole of the area chosen for study, but it is possible to assess results from the returns for the eastern half of the area north of a line Hebden Bridge/Todmorden/Rams- bottom. Apart from the wet summer which may have restricted observations and which doubtless had some effect on breeding, the only other factor which should be mentioned is the possible tendency for observers to have concentrated on the various built- up areas in the valleys to the exclusion of outlying hamlets and farmsteads, but many remote rural areas were fully covered, some with negative results.

PREVIOUS WORK So far as can be ascertained, this is the first large-scale survey VOL. LII] LANCASHIRE HOUSE MARTIN SURVEY 143 of House Martin colonies carried out in East Lancashire, but there have been previous studies in other parts of the country with which this one may be compared. Hurrell (1930) organized a survey of House Martins in Devon and Cornwall. Then a census was carried out in the Oxford area in 1931 and 1932 (Alexander, 1933), and in the next year (Cramp and Ward, 1934) there was a similar study for the Manchester area. The national sample census of Swallows (Hirundo rustica) in 1934 and 1935 (Boyd, 1935, 1936) included some data on House Martins, and finally there was a sample census in 1949 of Swifts (Apus apus), Swallows and House Martins in certain parts of London (Cramp, 1950).

NUMBERS OF BREEDING PAIRS A total of 486 nests were located in 122 colonies, nearly a quarter of which consisted of isolated single nests; this gives an average of a fraction under 4 (3.98) nests per colony. The largest colony contained 31 nests on two adjacent farm buildings at Whiteacre (Map Ref. 612402). The numbers of nests per colony are set out in Table I.

TABLE I—SIZES OF COLONIES OF HOUSE MARTINS (DeHchon urbica) IN EAST LANCASHIRE IN 1958 No. of nests per colony 1 2 3 4 5 6 7 8 9 10 11 12 13 14 21 31 No. of colonies 28 31 19 16 5 3 3 3 3 3 o 3 o 3 1 1 Thus over three-quarters of the colonies were of from 1 to 4 nests, though much larger groups occurred. The site with 21 nests was suburban and that with 31 nests was rural.

DENSITY The density of nests for the whole of the study area (452,000 acres) was found to be only 1.08 per 1,000 acres. All but 71 of the nests, however, were located in the greater eastern section of the study area which included the Clitheroe, Whalley and Wadd- ington environs and totalled approximately 333,000 acres: in this part the density figure averaged 1.25 nests per 1,000 acres. Further, by map-plotting nests in this eastern section it became obvious that most were located in five main zones, i.e.: — (A) South -east of Burnley. (B) South, west and north of Nelson. (C) North and south of Rawtenstall and Halsingden. (D) Between Whalley and Sabden in the south of the area, and Waddington and Grindleton in the north. (E) In the arc Colne/Salterforth/Barnoldswick/Gisburn/ Bolton-by-Bowland in the north-east. Records for these five main zones are shown in Table II. 144 BRITISH BIRDS [VOL. HI

TABLE II—COLONY-SIZE AND DENSITY OF HOUSE MARTINS (Delichon urbica) IN FIVE ZONES OF EAST LANCASHIRE IN 1958 The zones are detailed in the preceding paragraph (see also Fig. i). Approx. No. of No. of Av. nests Density per Area acreage colonies nests per colony 1,000 acres

A 5.000 16 65 4.06 13.0 B 3,000 25 112 4.48 37-3 C 10,500 19 52 2.74 4-94 D 13.500 27 87 3.22 6.46 E 18,000 14 52 3-72 2-9

50,000 101 368 3-64 7-36

GENERAL DISTRIBUTION That the House Martin is a suburban rather than an urban or rural breeding species has been well illustrated in previous surveys and is generally confirmed in the present study. Cramp and Ward (1934) and Oakes (1953) recorded the species as decreasing as an urban nester in the Manchester area. Cramp (1950) found the bird absent from Central London and his density figures for the inner suburbs were over 15 times greater than those for the outer suburbs which in turn were nearly twice those for the outskirts. Alexander (1933) for Oxford, found there were three times as many nests in urban and suburban areas as in rural. The plotted results of the present survey indicated clearly that the greatest concentrations of colonies occurred in the suburbs of the large towns, while the species was mostly absent from their centres. On the other hand, there were thriving colonies in purely rural areas, in which category, however, such small centres of human population as Whalley, Waddington, Grindleton, Gisburn and Bolton-by-Bowland, somewhat remote from the large industrial towns, are included. For the whole of the study area it was found that only 4 colonies (8 nests) were strictly urban, 60 colonies (224 nests) were suburban and 58 colonies (254 nests) were rural. It will be noticed there is no marked difference between suburban and rural totals, but this is due to the great size of the rural area included. The totals show that, while most colonies were suburban in location, these tended to contain less nests than those in rural areas, i.e. 3.73 nests per suburban colony as against 4.38 per rural colony.

DIRECTIONS FACED BY NESTS Aspects were recorded for 448 of the 486 nests; 193 of these faced from south to west, 145 from west to north, 157 from north to east, and 135 from east to south (the sum of these four figures exceeds the total number of nests because in each case, for reasons of convenience, both the limiting directions of the 90° arc have been included: in other words, the number of nests facing due west VOL. LII] LANCASHIRE HOUSE MARTIN SURVEY 145 is included in both the south-to-west and the west-to-north totals). In more detail, most nests faced south (63), south-west (52), north­ east (51), west (48), east (43) and north (28). Thus it seems, that direction has little significance and it is thought that the slight bias in favour of the south-to-west quarter is probably as much a reflection of the general direction faced by houses as of any preference on the part of the birds. By comparison, Hurrell (1930) found that 44 of 65 nests in Cornwall faced south, and that all of 126 nests in Devon looked south, south-east or south-west.

FRONTS, SIDES OR BACKS OF BUILDINGS Particulars of the position of the wall concerned were given for 451 of the 486 nests, and 342 (75.8%) of these were at the fronts of buildings while 87 were at the sides and only 22 at the backs. Thus there were 3! times as many nests at fronts as at sides and backs together. Any tendency for observers to check fronts alone is not considered to have been sufficient to influence unduly a clear preponderance of frontal sites. In the next section it will be noted that more nests were sited on terraced houses than on detached and semi-detached together, as might be expected with a majority of colonies in suburban areas where there are many terraced dwellings. This does, of course, restrict the number of "sides" available, but, on the other hand, it must be remembered that detached or semi-detached houses provide twice as many sides as fronts. Eaves at backs of houses seem frequently to be less suitable, being narrow or even non-existent. Of the 108 back and side nests for which the directions faced were given, 69 had a southerly aspect; and only 14 of the 63 such nests for which the necessary details are available overlooked no form of road.

TYPES OF BUILDING COLONIZED The type of building on which the nests were sited was recorded for all the 122 colonies (Table IV), but in the cases of 59 of them it was not clear from reports whether they fell under the category "detached", "semi-detached" or "terraced": these are classed as "unspecified" in Table IV and are detailed in Table V.

TABLE IV—BROAD CATEGORIES OF BUILDINGS COLONIZED BY HOUSE MARTINS (Delichon urbica) IN EAST LANCASHIRE IN 1958 Type of building Colonies Nests

Detached '4 57 Semi-detached 18 46 Terraced 3' '34 Unspecified 59 249

Totals 122 486 146 BRITISH BIRDS [VOL, LII

TABLE V—BREAKDOWN OF NEST-SITES OF HOUSE MARTINS (Delichon urbica) CLASSED AS "UNSPECIFIF.D" IN TABLE IV Type of building Colonies Nests

Chapels and schools 3 20 Post offices i 4 Mills and warehouses 3 12 Railway stations 4 18 Police stations i 2 Sheds and barns 8 32 Inns and hotels 4 14 "Residences" 20 70 "Farms" and "farmhouses " 13 44 Outbuildings 2 33 Totals 59 249

The variety in the types of buildings indicates that the House Martin is catholic in its choice of nesting-site, providing suitable eaves and other essentials such as food and mud supplies combine with reasonably open aspect. No preference for any particular style of eaves was evident, nor did the colour or surface of the surrounding wall (such as pebble-dash) seem to have any significance. It was frequently noted that many apparently ideal eaves with good approaches were not used when seemingly less adequate ones near-by were occupied. One observer suggested that the aspect of the nest holes might have some significance. He found that, where nests were built side by side under the same eaves, entrance holes were in different positions and apparently arranged to avoid having converging approaches with neighbouring nests. At a late check of the 21-nest site, however, though this variation in the position was confirmed, it was clear that the entrance holes of adjoining nests as often converged as not. PROXIMITY TO WATER Of the 122 recorded colonies, 70 (304 nests) were located close to main rivers or to their tributaries: 17 of these were adjacent to such waters while the other 53 averaged 350 yards from them. Of the remaining 52 colonies, details for one (3 nests) were not given, but 51 (179 nests) were all near some ample water-supply such as a reservoir, canal or major stream, 15 colonies being adjacent and the other 36 averaging 280 yards away. Distances of nests from water are given in Table VI, and show that 419 of the 483 nests for which there are appropriate details were within 400 yards of some major water supply; after this distance there is a sharp drop in the numbers and only two nests (one colony) were as much as 800-880 yards away. Thus the present study seems to confirm the correlation with food supply shown by Alexander (1933), Cramp and Ward (1934) and Cramp (1950). However, an alternative correlation might in this case be made with the availability of sites, for in Pennine areas the built-up parts largely follow the river valleys. VOL. LII] LANCASHIRE HOUSE MARTIN SURVEY 147

TABLE VI—DISTANCES FSOM WATER OF NESTS OF HOUSE MARTINS (Delichon urbica) IN EAST LANCASHIRE IN 1958 Distance No. of from water nests

Adjacent 120 Less than 100 yards 76 100-200 yards 77 200-390 yards 86 300-400 yards 60 400-500 yards IS 500-600 yards 15 600-700 yards 2S 700-800 yards 7 800-880 yards 2 Unknown 3

Total 486

DISTURBANCE OF COLONIES In the majority of instances where nests were known to have been destroyed, human interference was responsible. Such nests were mostly either removed by tenants of nouses or by visiting window-cleaners, and gutter-clearance and exterior redecoration accounted for twelve at a single site. Three nests on a farm build­ ing were deserted through the attentions of a cat which had near access via a ladder. Only twelve nests were known to have been usurped by House Sparrows (Passer domesticus).

PARASITES A number of ectoparasites were collected both from nests and dead birds. Examples from Edenfield included the flea Ceratophyllus h. hirundinis (Curtis) and the flat-fly Stenepteryx hirundinis (L.), the latter new to Lancashire. Fleas from Slaidburn included Ceratophyllus h. hirundinis, Ceratophyllus f. farreni (Roths.) and Ceratophyllus rusticus (Wagner), the last new to Yorkshire. Slaidburn, like Edenfield, also provided Stenepteryx hirundinis and in this connection it is interesting to note the reference to this species in Boyd (1936, p. in): there it is quoted as being the commonest parasite of Swallows and House Martins in France, though it was not recorded from Swallows' nests in the British Isles during the 1934-35 Enquiry. Parasites were determined by R. S. George of Gloucester.

ACKNOWLEDGEMENTS The compiler wishes to acknowledge with thanks the help of the following observers and correspondents who supplied much of the information on which this paper is based: Mrs. E.C.Barnes, J. Bentley(and members of theTodmorden Natural History Society), H. A. Bilby, J. Boon, A. W. Boyd, A. J. Bull, R. Burr, S. Cramp, 148 BRITISH BIRDS [VOL. LH

R. C. Cross, E. Davis, P. Durham, F. Elliman, W, Farron, Miss J, M. Ferrier, J. C. Follett, Rev. and Mrs. Frankiand, R. S. George, K. Halstead, P. A. D. Hollom, R. C. Homes, H. G. Hurrell, P. I'Anson, M. Jackson, D. Jones, R. Kingsmitl, D. Lamb, B. Mansfield, Newchurch School, K. G. Spencer, Dr. Stuart Smith, H. Smithies, D. Sodo, G. W. Ternperley, J. M. Tomlinson, E. Ward, S. Ward, J. Webster, A. Welch, R. Wilson, D. Windle, T. Wood.

SUMMARY 1. A survey of House Martin colonies was carried out by members of the East Lancashire Ornithologists' Club in an area of 15 miles radius from the centre of Accrington in 1958. 2. Owing to incomplete coverage of the study area (452,000 acres), returns for an eastern section of 333,000 acres were mainly considered. For the larger area, however, 122 colonies totalling 486 nests were located. 3. Over three-quarters of the colonies consisted of from 1 to 4 nests, but the remainder included groups of 14 (three), 21 and 31 nests. 4. Breeding was found mainly in five distinct zones totalling approximately 50,000 acres and mostly in centres of heavy human population. These zones contained 101 colonies with a total of 368 nests, the density of breeding pairs being 7.36 per 1,000 acres, as against 1.25 for the eastern section as a whole and 1.08 for the complete study area. 5. Most colonies were' in the suburbs of the industrial towns, only two being strictly urban. While there was not a great difference in the total numbers of colonies between suburban areas and rural areas, this was due to the great size of the rural area included. Colonies in rural areas, however, tended to contain more nests than those in suburban areas. 6. Aspects of 448 of the 486 nests seemed to show that direction had little significance, with possibly a slight tendency to face the south-to-west quarter. 7. Analysis of 451 nests showed that numbers on fronts of buildings were 3$ times greater than the sum of those on sides and backs. 8. The survey confirmed that the House Martin is catholic in its choice of the type of building to colonize. g. 419 of 483 nests were within four hundred' yards of some major water supply and only two nests were further than eight hundred yards from such water. 10. Human interference was the chief cause of nest-failure and only 12 nests were known to have been taken over by House Sparrows. A number of ectoparasites were collected and some details are given. REFERENCES ALEXANDER, W. B. (193.1): "A census of House-Martins; are their numbers decreasing?" Journ. Min. Agric, 40: 8-12. BOYD, A. W. (1935): "Report on the Swallow Enquiry, 1934". Brit. Birds, xxix: 3-21. VOL. LII] LANCASHIRE HOUSE MARTIN SURVEY 149

(1936): "Report on the Swallow Enquiry, 1935". Brit. Birds, xxx: 98-116. CRAMP, S., and WARD, J. H. (1934); "A census of House-Martins and Swallows near Manchester, 1933". /. Anim. Ecol., 3: 1-7. CRAMP, S. (1950); "The census of Swifts, Swallows and House-Martins, 1949". London Bird Report, No. 14, pp. 49-57. HURRELL, H. G. (1930): "A survey of House-Martins in Devon and Cornwall". Western Morning News. OAKES, C. (1953): The Birds of Lancashire. Edinburgh.