Ruddy Ducks in Britain Robert Hudson

INTRODUCTION The Ruddy Duck Oxyura jamaicensis is one of five introduced birds (three waterfowl and two pheasants) that were admitted to the British and Irish list in 1971, when it was accepted that they had succeeded in establishing self-maintaining feral populations in these islands (British Ornithologists' Union 1971). Some notes on the status of the present species were given by Parslow (1973), in the course of a general review of British and Irish breeding birds; but, hitherto, no full account of the Ruddy Duck in this country has appeared, despite the growing volume of observations scattered in county and regional bird reports and bulletins. This paper is intended to correct this deficiency, and at the same time ensure that the early history of the colonisation of Britain by the Ruddy Duck is better documented than has been the case for most intro­ duced species.

AVICULTURAL BACKGROUND The Ruddy Duck, a North American species, is known to have acquired feral status mainly through strays from the Wildfowl Trust's collection at Slimbridge in Gloucestershire. Therefore some account of the avicultural background is relevant, and this has been provided {in litt.) by Wildfowl Trust staff. Until fairly recently this species was regarded as difficult to breed or even keep in captivity, and very few waterfowl collections contained it. During the i93o's a nesting pair was held at Walcot, Shropshire {Avic. Mag., 1938: 104-105), but this collection was dispersed during the Second World War. The post-war reappearance of the species in British aviculture was initiated by the Wildfowl Trust, which imported three pairs from the USA in 1948; these began breeding at Slimbridge in 1949. However, young Ruddy Ducks proved difficult to rear by the artificial techniques then in use. It was soon found that the best results could be obtained by permitting parents to rear their own young, and from 1955 most Slimbridge pairs were allowed to do so; four young were raised naturally in 1952, five in 1954, twelve in 1955, 17 in 1956, about 40 in 1957 and again in 1958, and between ten and 40 annually thereafter (see Wildfowl Trust Annual Reports). It has long been the policy of the Wildfowl Trust to pinion the young of non-native ducks as far as practicable. Where Ruddy Ducks were concerned, this worked well provided the nests were located before incubation commenced, so that the hatching date

132 [Bril. Birds, 69: 132-143, April 1976] Ruddy Ducks in Britain J33 could be calculated. (The ducklings remain in the nest for several hours after hatching, and it is then they must be caught for pinion­ ing.) Even small ducklings, once they have taken to the water, can dive well, and they cannot then be caught without causing an unacceptable degree of disturbance in the pens, which is especially to be avoided during the breeding season. As the Slimbridge breeding stock increased (three pairs in 1955, ten by 1958) not all nests were found in time, and so some broods escaped pinioning. The first full-winged young left Slimbridge in the winters of 1952/53 (two) and 1954/55 (one); but the first major departure occurred in the autumn of 1957, when up to 20 birds escaped (Ferguson-Lees 1958). No accurate figures exist for the numbers of Ruddy Ducks which left Slimbridge in subsequent years; but S. T. Johnstone believes that 70 birds would be an approximation for the total number of escapes up to his retirement in 1973, most of them during the first half of the period. Certainly all full-winged Ruddy Ducks left Slimbridge during the terrible winter of 1962/63, when many of the pinioned birds succumbed. Since that time fewer birds have avoided pinioning, though there remains the problem of the occasional Ruddy Duck egg being laid in another species' nest and overlooked; while from 1973 Ruddy Duck broods have again been reared artificially. In recent years (at least since 1969) it is unlikely that more than one or two individuals per annum have escaped from Slimbridge. Ruddy Ducks are now included in a number of specialist water­ fowl collections elsewhere (Martin 1974), though no complete list is available. Several Wildfowl Trust birds were taken in 1957 to the Peakirk collection in the Soke of Peterborough; but fewer young are reared there, and the number of strays has always been insignificant. A fair number of young are reared in private collec­ tions at Apethorpe (also in the Soke of Peterborough), at St Neots in Cambridgeshire, near Grimsby in South Humberside, and at Monken Hadley near Barnet in Hertfordshire. In such collections the emphasis is on artificial rearing, improved techniques having been devised, so that the majority will be pinioned (Dawson 1974, Wildfowl Trust); but it is known that over the years a number have been allowed to fly free from the Monken Hadley collection. Away from centres of feral breeding, Ruddy Duck records are often published in local bird reports as referring to probable escapes; some undoubtedly are, especially in south-east England, but, in practice, escapes must nowadays be well outnumbered by wander­ ing birds of feral origin. The Wildfowl Trust does not now countenance the accidental or deliberate releasing of non-native birds into the wild. Ruddy Ducks got away and established themselves ferally at a time when 134 Ruddy Ducks in Britain the potential dangers of introducing alien species were not so clearly appreciated as they are now. However, in the present case it must be conceded that no harm appears to have been done to any native species or habitat, nor is there any danger of this essentially aquatic species becoming an agricultural pest. This is just as well because, as the following sections will show, feral Ruddy Ducks are successful and increasing, and all the signs are that they are here to stay.

FERAL DISTRIBUTION The first Ruddy Ducks reported at liberty in this country were in 1954, when single drakes were seen at Hingham, Norfolk, in April and at Carsebreck, Perthshire, in June (per Wildfowl Trust); these were 250 km and 510 km respectively from Slimbridge, and presumably referred to one or both of those which escaped from there in the 1952/53 winter. There is also a puzzling record of five stifftail ducks (three males, two females), possibly jamaicensis, seen on Aqualate Mere, Staffordshire, in August 1954; if these were Ruddy Ducks they would be difficult to account for (exceeding the number of Slimbridge escapes up to then), but the description on Slimbridge files is not wholly satisfactory. The initial intimation that a feral population might develop in Britain was given by King (1961). In 1957, the first year that a substantial number left Slimbridge, a young Ruddy Duck appeared in November on Chew Valley Reservoir in what is now the county of Avon. During the ensuing winter the number present at Chew increased to four, while four birds (presumably the same ones) were also seen for long periods on nearby Blagdon Reservoir, as well as a single bird on Barrow Gurney Reservoir—making five in all. By the spring of 1958 it was apparent that these were all drakes, as also were the one or two additional immatures which arrived in 1958/59. According to contemporary Somerset and Bristol Bird Reports, the first females appeared at Chew in December i960; but King (1976) has stated that he saw a brood of ducklings there in May i960. A single pair bred again in 1961, and this species has probably nested there in most years since. It has been generally understood that the English feral popula­ tion arose solely from Slimbridge escapes and their progeny (e.g. Campbell and Ferguson-Lees 1972). However, in the early years one deliberate release was made by the Wildfowl Trust, with three of four immature females from Slimbridge being turned down on Chew Valley Reservoir in the autumn of 1961 (B. King and Wild­ fowl Trust, in litt.). This was done ostensibly to provide mates for the drakes already present, though it should be noted that these young females were released after feral breeding had occurred there. Ruddy Ducks in Britain !35 In the event, this deliberate release had no discernible effect on the development of a feral population, as is shown by the fact that the Chew breeding numbers remained static at one or two pairs until the 1970's (see below). In September 1959 Ruddy Ducks also began appearing on certain Staffordshire reservoirs, where feral breeding was con­ firmed in 1961. These west midlands birds, now breeding in six or seven contiguous counties, arrived and multiplied unaided, and soon came to outnumber the lower Severn breeding population. This west midlands stock is also assumed to be derived from full- winged Slimbridge escapes and their progeny (e.g. Lord and Munns 1970), and I have no doubts that this view is correct, notwithstanding the problematical (and indeed questionable) 1954 record from Aqualate Mere mentioned earlier. Certainly, the numbers of Ruddy Ducks known to have left Slimbridge are well in excess of those which setded to breed in lower Severn counties. Details of subsequent expansion and of present status are given below under counties, beginning in the south-west and continuing northwards.

Avon First bred in i960 on Chew Valley Reservoir; this remains the sole Avon breeding site and only one or two pairs nested up to 1971. Four pairs summered in 1972, six in 1973 and 1974, and about the same number in 1975; but not all of these necessarily attempted nesting. Significant autumn/winter flocks are a regular feature, with some commuting between Chew and Blagdon Reservoirs though the latter has held most in recent winters; these flocks generally reach peak numbers about December, and disperse during March. Combined totals for these two waters have increased steadily: November 196a, seven; December 1963, 15; October 1966, 24; February 1969, 42; January 1971, 55; January 1973, 68; December 1974, about no; November 1975, about 120 (in on Blagdon). The majority of these are winter visitors from elsewhere (a count of 32 at Chew in September 1975 indicated the maximum size of the local population), but the areas from which they are drawn have yet to be confirmed. (See discussion under POPULATION AND DISPERSAL.) (See also postscript on p. 142.)

Gloucestershire Surprisingly, the species is not mentioned at all in Gloucestershire Bird Reports, whose editors are perhaps conditioned to ignoring strays from Slim­ bridge. Atkinson-Willes (1963) mentioned breeding on pools at Frampton-on- Severn, but the year of commencement is not recorded; a pair attempts to breed there in most years, though few young are reared, perhaps owing to predation by Pike Esox lucius (M. A. Ogilvie). The maximum number seen there is 14, in November 1969. No other Gloucestershire feral breeding sites are known.

Hereford & Worcester Since 1967 Ruddy Ducks have occurred regularly in Westwood Park and Upton Warren (both near Droitwich), and nesting was proved at both sites in 1971; in 1975 one pair bred at the former and two or three pairs at the latter. At Pirton Pool (near Pershore) there have been almost annual spring or summer occurrences from 1970 (four birds present in June 1972); but nesting remains unproven. Further west a single drake was seen at Hereford in January 1963, but no more until July 1975 when a pair was located on Eywood Pool (near Titley), a suitable breeding site (A. J. Smith). 136 Ruddy Ducks in Britain Warwickshire Records from 196a; annually from 1971, following continued increase in adjacent Staffordshire. Apparently nesting has not yet been formally proved, but probably is occurring. In 1974 up to four birds were present on Alvecote Pools from April to December, a pair was seen in Packington Park in July and August, and up to five birds (some juveniles) were present on Middleton Hall Pools between July and November. Birds were again present at Alvecote and Middleton Hall in summer 1975. Future colonisation seems assured, if this has not already occurred.

Staffordshire First bred in 1961, when single broods were seen on Gailey and Belvide Reservoirs (Lord and Munns 1970). There has been only one subsequent definite breeding record for Gailey (in 1962), but Ruddy Ducks are thought to nest most years at Belvide, where there were three pairs in 1962 and 1974 (other­ wise one or two). In recent years they have occurred regularly in summer on Copmere near Eccleshall (breeding from 1968, four pairs displaying in April 1974), on White Sitch near Weston-under-Lizard (breeding proved in 1971 and 1972, probably regularly since), at Chillington near Codsall (probably bred 1974, proved 1975), and on the heavily-reeded Aqualate Mere (assumed to be breeding; five pairs present in April 1974). Betley is another possible nesting site. Stafford­ shire is also notable for its autumn/winter flocks, involving regular movement between two main centres—Belvide and Blithfield Reservoirs. In recent winters flocks have formed on Belvide during September-November, and around November-December many have transferred to Blithfield and remained there until the spring dispersal (March-April). Total numbers have increased steadily despite a temporary setback after the severe winter of early 1963: December 1962, 13; winter 1965/66, 15 to 20; September 1967, 20 to 25; November 1969, 35 to 40; December 1972, 70 to 80; November 1974, no; October 1975, about 190 (181 at Belvide). Many must be winter visitors from elsewhere. (See postscript on p. 142.)

Salop First seen in 1962; first proven breeding in 1965 at Crosemere, where it has probably nested annually since, with four pairs present in May 1975 (C. E. Wright). Since 1969, Ruddy Ducks have been reported with increasing regularity from small pools and meres in most parts of the county, but especially from the area between Ellesmere and Market Drayton and north to the Cheshire boundary. Breeding has occurred at Ossmere since 1971 (three pairs in 1974; in 1975 two pairs summered but did not breed owing to low water levels), and at Hawk Lake since 1974 (six males, five females and six ducklings in September 1975); and is thought to be occurring at Cloverley Pool (two pairs present in May 1975) and nearby Shavington (three pairs in June 1975), while in 1975 summering pairs were also located on Berth Pool and Birchgrove Pool, both in the Fenemere group near Baschurch. There have also been summer reports from several other sites where it is conceivable that nesting may have been attempted: Colemere, Tittenley (near Shavington), Norton Mere (near Tong), Allscott Pools (near Telford), and Marton Pool (near Chirbury). Small numbers winter on Crosemere (eleven birds in January 1975), and at least occasionally on Ossmere; but the general paucity of records at that season, plus the fact that the largest flock reported from the county in any month is one of only 17 birds (Crosemere in November 1969), suggest that the majority leave Shropshire for the winter.

Cheshire Date of colonisation is uncertain. It was said in 1968 that Ruddy Ducks had occurred on several meres, most often Barmere (near Malpas); the species was not mentioned in local bird reports for 1969 or 1970, but in 1971 it was stated that this duck had bred previously on Barmere, while the (nearby) 'colony at Quoisley Mere continues to flourish'. Breeding occurred at Barmere, Cholmondely and probably Quoisley (all near the Salop boundary) in 1972, and this is believed Ruddy Ducks in Britain 137 still to be the main Cheshire population centre; 35 birds were present on Barmere in October 1974 (the largest county flock recorded), while there were three males (presumed breeding) on Quoisley Mere in June 1975. Further north, in the Mac­ clesfield area, it has occurred annually since 1970, breeding at least from 1973, at Capesthorne and Redesmere, and there were three pairs on the latter in 1974. In 1975 a pair nested on Oakmere (near Delamere) (per Eric Hardy). The afore­ mentioned are the only confirmed breeding waters, but probably there are others; there were two or three displaying pairs on Rode Pool (near Alsager) in 1973, 1974 and 1975, though no young have yet been seen (R. West), and other summer occurrences have been reported from Marbury (near Malpas), Combermere, Doddington Park and Budworth Mere. The Ruddy Duck appears to be successful and increasing in Cheshire, but numerical data are sparse. Apparently a few birds winter on Barmere (maximum of 13, in January 1974), but the small number, and rarity elsewhere at that season, indicate that most Cheshire birds move away for the winter. Rostherne and Tatton Meres (near Knutsford) have provided annual non-breeding records from 1972, and are the northernmost 'regular' localities in Britain at present.

Derbyshire Occasional visitor from 1963, but with an increasing number of records during the last three years. In 1975 a drake was present in Osmaston Park (near Ashbourne) during July; this site was not visited in August, but a female with one half-grown duckling was seen there in September (Miss K. M. Hollick).

Leicestershire First reported in 1961 but only an irregular visitor until 1973, in which year two pairs bred successfully at Swithland Reservoir, as did two pairs in 1974. Now resident, with some commuting between diere and nearby Groby Pool. In 1975 three pairs were displaying at Swithland in spring, and two broods were noted (April, June) though apparently no young were reared; while a pair also summered on Groby Pool, where display was seen but no evidence of breeding was obtained. There were eleven Ruddy Ducks in Leicestershire, all at Groby Pool, in December 1975 (Miss J. Ironside).

Hertfordshire First reported in i960. One pair bred on the Tring Reservoirs in four consecutive years, 1965 to 1968, but failed to colonise for reasons unknown. Since that time the Ruddy Duck has been seen only occasionally there or else­ where in the county. Hertfordshire is well separated from other areas of feral breeding, and records here may relate to strays from an ornamental waterfowl collection at Monken Hadley near Barnet.

Some mention of wandering Ruddy Ducks will be made in the following section. It proved impossible to gather non-breeding records systematically since the majority of county bird reports did not bother to record this species until its formal admission to the British and Irish list in 1971, and some still do not do so.

POPULATION AND DISPERSAL Ruddy Duck drakes are conspicuous, and occupied waters are therefore unlikely to be overlooked to any significant extent, with the possible exception of lakes in private parks to which bird­ watchers have limited access. However, proof of breeding is more difficult to obtain; females are much duller birds, their nests are i38 Ruddy Ducks in Britain well concealed, while the species tends to breed late in the summer when broods can remain for much of the time within the thick cover of reed beds. This has to be borne in mind when interpreting the foregoing distribution paragraphs. Based on the records given under the previous section, it would seem that current county totals of pairs are: Avon, five or six; Gloucestershire, one; Hereford & Worcester, three to five; Warwickshire, probably one or two; Staffordshire, ten to 15; Salop, about 15; Cheshire, twelve to 15; Derbyshire, one; and Leicestershire, two or three. This indicates a national total in the region of 50-60 feral nesting pairs, spread over nine counties. In 1961 the English feral population consisted of three known breeding pairs, rising to six in 1962 (Avon one, Gloucestershire one, Staffordshire four). Following the severe winter of 1962/63, which caused widespread avian mortality, only four breeding pairs of Ruddy Ducks were known in 1963 and 1964. However, the national total returned to six pairs (in five counties) in 1965, and increased steadily thereafter—at least ten pairs (five counties) in 1968 and 20 pairs (six counties) by 1971, about 35 pairs (seven counties) in 1973, and 40 to 45 pairs (eight counties) in 1974. On the basis of the somewhat incomplete data available on breeding pairs and winter flock counts, it would seem that during the period 1965-75 the overall rate of increase averaged about 25% per annum. As suitable waters become colonised, it is inevitable that this rate of expansion will slow down. The increase during the last decade has doubdess been helped by the series of mild winters, while the virtual absence of shooting pressure must have aided the species also. However, the Ruddy Duck could hardly have estab­ lished itself so quickly and so firmly as a feral species unless there had been a vacant niche for another freshwater diving duck adapted to breeding on smaller waters. The degree of ecological separation from the native Pochard Aythyaferina and Tufted Duck A.fuligula has yet to be ascertained, though the latter is known to take a much higher proportion of animal foods. The isolated Leicestershire 'colony' appears to be discrete at all seasons, the birds wintering on or near the natal reservoir. Elsewhere, there is a pronounced tendency for regular seasonal displacements, with substantial winter flocks forming on certain reservoirs in Avon and Staffordshire, and involving larger numbers than breed or are reared in those counties. As explained previously, there are rather few nesting pairs in lower Severn counties, the main breeding strength being in the west midlands. From this, it follows that the substantial numbers of winter visitors to the Avon reservoirs must come from the west midlands, possibly involving some movement up and down the River Severn, which flows Ruddy Ducks in Britain 139 through Salop and the old county of Worcestershire. It is noticeable that the Staffordshire flocks reach a peak in late October or Novem­ ber, at least a month earlier than in Avon; and it has been speculated that there may be onward movement from the former to the latter. An examination of winter numbers in Staffordshire suggests that some such movement is possible, but only on a small scale. During the 1974/75 season the two main Staffordshire reservoirs together held 94 in October and no in November and, though lower numbers (up to 80) were reported there in December and January, 92 were counted in February; while in the closing months of 1975, 181 were present in October and up to 150 were accounted for during November-December. On this basis, it would seem that many, if not the majority, of Avon's winter visitors must fly there direct from breeding waters. There are no ringing data concerning movements within Britain, and at present the natal counties of Avon's winter visitors are unknown. The early flocking on Belvide Reservoir in Staffordshire (in 1975 there were 100 as early as 6th September) could be accounted for by this being a major assembly point for non-breeders and failed breeders. (See postscript on p. 142). In the closing months of 1975 there were about 120 birds in Avon, about 190 (apparently dropping later to about 150) in Staffordshire, and eleven in Leicestershire. Assuming that there were also small numbers wintering in Salop and Cheshire as in previous years, and allowing for scattered birds elsewhere at that time (e.g. three or four each in Derbyshire and Northamptonshire), it would seem that the 1975 post-breeding population was in the order of 300 to 350 birds. This includes adults, juveniles and other immatures, and it should be noted that most Ruddy Ducks do not breed until two years old (Ogilvie 1975). Ruddy Ducks are seen from time to time not only on non-nesting waters in colonised counties, but also in other counties, sometimes far from any breeding centre. Since many Ruddy Ducks do not reach maturity until two years of age, it seems likely that these wanderers include immatures prospecting for future nesting sites. For this reason alone, all such occurrences are worth recording. It is impossible to be sure whether isolated records in uncolonised counties relate to wandering feral birds or to strays from ornamental waterfowl collections, though (as mentioned earlier) the latter are believed to be very much in a minority. Escapes are no doubt equally capable of moving long distances. Before feral breeding began there were isolated Ruddy Duck records from places as far apart as Perthshire, Lancashire, Merseyside, Norfolk, Essex, Berkshire and Buckinghamshire, which, presumably, related to wandering Slimbridge escapes. As would be expected, reports of itinerant birds nowadays come most often from counties adjacent 140 Ruddy Ducks in Britain to those in which there is feral breeding, notably Somerset, Wiltshire and Northamptonshire; in the latter, a pair was seen on Naseby Reservoir in June 1975 though there was no adequate follow-up to check on possible nesting (G. J. Coe in lift.). Had this paper been written six months earlier, Derbyshire would also have been included here, but there was a breeding record in the county in September 1975; it remains to be seen whether this will be con­ solidated. In recent years there have been a growing number of occurrences in Cambridgeshire and the Home Counties—Greater London (including a party of five on Island Barn Reservoir in June 1973), Essex, Hertfordshire (has bred) and Buckinghamshire; but records from the south-east are complicated by known escapes from the Hertfordshire collection. Most of Wales is too high and rugged for this species, which is only a straggler to the Principality; single birds were seen in Mid Glamorgan in September 1972 and South Glamorgan in January 1973, a non-breeding pair summered at Montgomery, Powys, in 1974 (R. R. Lovegrove in litt.), and one was seen in Clwyd in January 1970; these counties are all within reasonable distances of breeding centres (lower Severn, Salop and Cheshire respectively). To the north of the breeding range, Ruddy Ducks were recorded in Lincolnshire in 1968, Greater Manchester in 1975, Lancashire in 1959, 1968, 1972 and 1975, and in North Yorkshire in 1968, 1969 and 1974. Scotland has produced two records to date; one from Perthshire in 1954 has already been mentioned, but is easily eclipsed by the appearance of a drake in May 1974 on the island of Unst in Shetland. The latter was 840 km from the nearest feral breeding site, though its actual origin it is impossible to decide.

HABITAT AND BREEDING The nest of the Ruddy Duck is usually a platform of rushes or reeds concealed in lush aquatic vegetation, often a floating structure, like that of a Coot Fulica atra, anchored to stems in a reed bed, occasionally in a clump of rushes surrounded by water. It follows, therefore, that a breeding water should have one or more sizeable areas of emergent vegetation, normally dominated by reed Phragmites, bulrush Scirpus or reedmace Typha. Another requirement is that the water must not be too deep, or at least have shallow edges or bays, since Ruddy Ducks feed on waterweed and on insect larvae and aquatic plant seeds obtained by straining bottom ooze during underwater dives to depths of about three metres (Ogilvie 1975, Siegfried 1973). Flowing waters such as rivers are avoided, the preference being for freshwater pools (including some flooded gravel pits), lakes and reservoirs, large or small. Meres used for breeding in the west midlands may be only three ha in extent, Ruddy Ducks in Britain 141 while, at the other extreme, Ruddy Ducks breed on some large man-made reservoirs where, however, breeding densities are restricted by the areas of emergent vegetation available for nesting. Thus, Chew Valley Reservoir has the low density of five to six pairs for its 500 ha. At other seasons, too, Ruddy Ducks remain on still, freshwater bodies; rarely are they encountered even then on rivers, and I know of only two occurrences on tidal water: a party of five in, the Dee estuary off Hilbre Island, Merseyside, in September 1959 (Brit. Birds, 52: 436-437) and one at Chittening on the Severn estuary in December 1974. Went (1975) thought the Merseyside record indicative of transatlantic vagrancy, but a Slimbridge origin seems to me more likely. There is a marked tendency for feral Ruddy Ducks to vacate the smaller breeding pools and meres in autumn and winter, when large flocks develop on certain reservoirs, notably at Chew Valley, Blagdon (150 ha), Belvide (80 ha) and Blithfield (320 ha). All of these are characterised by having largely natural margins and shallow bays; large reed beds are not essential outside the breeding season, and do not exist at Blagdon and Blithfield Reservoirs. The winter aggregations are more often long, straggling lines of birds than compact flocks, and at times they are scattered among rafts of other diving ducks. Ruddy Ducks are aquatic birds at all times; only on rare occasions does the single bird come out of the water to feed on the banks. Their legs are set well back like those of grebes (Podicipitidae) so diat they walk awkwardly on land, and no doubt this is one reason why their nests are usually over water rather than ashore. When the female is flushed at the nest, she is apt to dive and re­ surface in the centre of the pool, while alarmed birds may swim with only the head above water. These are further grebe-like character­ istics. On the water, Ruddy Ducks are in their natural element, swimming buoyantly and diving with ease, and they also have the uncanny ability to sink gently beneath the surface without a proper dive. In the Slimbridge collection the earliest egg date is 17th April (1964) and the latest hatch is 28th August (1965), the median date for first eggs over 20 years being 19th May (Wildfowl Trust); but little information is available on the timing of the feral breeding season in Britain (Campbell and Ferguson-Lees 1972). Though one very early brood has been reported in April (Leicestershire 1975, following an unusually mild winter), and a number in May and June, it is more usual for small ducklings to appear in July, August or even early September; while a small duckling was seen at Chew Valley on 31st October 1965. Evidently the Ruddy Duck has one of the latest breeding seasons of British waterfowl. 142 Ruddy Ducks in Britain SUBSPECIES As mentioned at the beginning, the Wildfowl Trust imported its stock from the USA. Thus the British feral population is of the Nearctic subspecies, nominate jamaicensis, in which the drakes have conspicuously white cheeks. In the Neotropical races, andina and femtginea, there is progressive reduction in the amount of white on the head.

EPILOGUE The way that the Ruddy Duck has established itself so firmly and within so short a period leads one to assume that it is now a part of the British avifauna for the foreseeable future. It has found accep­ table conditions in the west midlands and other western counties, and continues to increase. There is seemingly suitable habitat in Yorkshire, the east midlands, East Anglia and the Home Counties, in the form of lakes, broads, reservoirs, gravel pits and flooded mining subsidence; thus further expansion can be expected. The ultimate test for a migratory species introduced to another continent is whether it can tolerate the climatic extremes of its new environment. This is particularly relevant, since there are indica­ tions that Britain is on the threshold of a cooler climatic phase. However, in its early days here the Ruddy Duck survived one of the coldest winters this century, so there is no reason at present to suppose that this species will fare less well than many native ones as we move into climatic recession.

POSTSCRIPT During the short spell of cold weather in late January/early February 1976, many small meres and pools in the west midlands froze over for the first time in at least six years. On 8th-gth February no fewer than 221 Ruddy Ducks were counted on die ice-free Staffordshire reservoirs (110 on Belvide and 111 on Blithfield), the highest number ever recorded in the county (D. Smallshire). That same weekend 130 were present in Avon, where a record figure of 154 had been counted on 12th January {per R. Prytherch). Together, these data further indicate that there can be little same-season movement between the Staffordshire and Avon winter flocks.

ACKNOWLEDGEMENTS It is a pleasure to thank past and present Wildfowl Trust staff for their help: S. T. Johnstone (curator until 1973) provided much useful information on the early days of the Ruddy Duck at Slimbridge; while Professor G. V. T. Matthews, Dr Janet Kear and M. A. Ogilvie read an early draft and made many helpful suggestions. Local recorders and observers who provided supplementary records, and to whom I extend my thanks, are: B. King and R. Prytherch (Avon); A. J. Smith (Herefordshire); E. S. Clare, B. R. Dean, G. R. Harrison, J. Lord, J. N. Sears and D. Smallshire (West Midland Bird Club); C. E. Wright (Salop); J. Ruddy Ducks in Britain 143 Davies, E. Hardy, Dr R. J. Raines and R. West (Cheshire); Miss K. M. Hollick (Derbyshire); Miss J. Ironside (Leicestershire); C. J. Coe (Northamptonshire); K. G. Spencer (Lancashire); and R. R. Lovegrove (Powys). Finally, I thank all those bird report editors who had the foresight to record this species prior to its formal admission to the British and Irish list.

SUMMARY The Ruddy Duck Oxyura jamaicensis is an introduced freshwater species which was admitted to the British and Irish list in 1971. This feral population stems from the Wildfowl Trust's Slimbridge collection, through escapes and their progeny; one small, deliberate release proved ineffective. Feral breeding commenced in i960, and the species has since increased steadily in numbers and range despite a temporary setback caused by the severe winter of 1962/63. Over the period 1965-75 the rate of increase appears to have averaged about 25% per annum. Ruddy Ducks are now nesting in eight or nine counties; in 1975 there were 50 to 60 pairs, and a post-breeding population of 300 to 350 birds. Habitat is described; small meres and pools are mostly deserted in winter, when flocks form on four large reservoirs in Avon and Staffordshire. Some notes on dispersal are also given.

REFERENCES Most of the data used have been culled from the many county and regional bird reports and bulletins. Items cited in the text are: ATKINSON-WILLES, G. L. 1963. Wildfowl in Great Britain. Nature Conservancy Mono• graph no. 3. London. BRITISH ORNITHOLOGISTS' UNION. 1971. 'Records Committee: sixth report (February 1971)'. Ibis, 113: 420-423. CAMPBELL, B., and FERGUSON-LEES, I.J. 1972. A Field Guide to Birds' Nests. London. DAWSON, L. R. 1974. 'Rearing the North American Ruddy Duck'. Avic. Mag., 80: 237. FERGUSON-LEES, I.J. 1958. "The identification of the White-headed and Ruddy Ducks'. Brit. Birds, 51: 239-240. KING, B. 1961. 'Feral North American Ruddy Ducks in Somerset'. Wildfowl Trust Ann. Rep., 12: 167-168. 1976. 'Association between male North American Ruddy Ducks and stray ducklings'. Brit. Birds, 69: 34. LORD, J., and MUNNS, D. J. 1970. Atlas of Breeding Birds of the West Midlands, 1966-1968. London. MARTIN, R. M. 1974. 'The North American Ruddy Duck in captivity'. Avic.Mag., 80: 132-135. OGILVIE, M. A. 1975. Ducks of Britain and Europe. Berkhamsted. PARSLOW, J. L. F. 1973. Breeding Birds of Britain and Ireland. Berkhamsted. SIEGFRIED, W. R. 1973. 'Summer foods and feeding of the Ruddy Duck in Manitoba'. Canad.J.Zool., 51: 1293-1297. WENT, R. 1975. 'Rare birds: the North American Ruddy Duck'. Bird Life, 1975: 18-19.

Robert Hudson, British Trust for Ornithology, Beech Grove, Tring, Hertfordshire HP23 5NR