Common Coot feeding young, Blagdon Lake © Nigel Milbourne, 2006
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Species Accounts
This feature of the website will be revised and added to over the coming years as I add research notes. Species will be listed in the BOU order.Accounts are written in the following format:
Current English name (BOU list), scientific name and authority.
Abundance:
- Accidental - Five or less records
- Very Rare - Twenty or less records
- Rare - Less than annual; many years between records
- Very Scarce - Less than annual; typically every 2 or 3 years
- Scarce - Very small numbers virtually every year
- Uncommon - Recorded in low numbers each year
- Fairly common - Occurs in reasonable numbers
- Common - Regularly occurs in good numbers
- Abundant - Occurs in large numbers
Occurrence:
- Resident
- Summer Visitor
- Winter Visitor
- Passage Migrant
- Introduction
- Feral
- Vagrant
- Storm Driven
General Notes
Early Years (1898 – 1973)
Recent Years (1974 - 2009)
Best Locations to View
Mute Swan Cygnus olor (Gmelin, 1789)
(Uncommon or Fairly Common Resident, PM & SV, Mar. to Nov., that has occurred in every month. Scarce breeder.)
Mute Swans, Blagdon Lake © Nigel Milbourne, 2008
General Notes
Cecil Smith (1869) wrote that the Mute Swan was introduced into this country during the reign of Richard I, who is said to have brought it from Cyprus. However, the British Ornithologists Union commented in the Records Committee’s Sixth Report (Ibis : 420-423) in 1971 that: ‘Mute Swan is in Category A because wild immigrants occur and because most of the breeding population is derived from semi-domesticated descendants of wild stock rather than artificially introduced’. Whatever their provenance, it is undeniably true that Mute Swans have long been domesticated and used for food, especially in the Middle Ages (Cramp & Simmons, 1978).
Early Years (1898 – 1973)
Smith also stated "hardly any large piece of water in the county is without a pair or more of these beautiful birds." So, it is reasonable to assume that they would have taken up residence as soon as the reservoir was flooded. However, the earliest record I have been able to find is from 'A Visit to Blagdon Lake, May 1925' a photocopy of bird notes made by Dr. L.P. Ashton during a bicycle visit with two fellow pupils at Clifton College. The following birds were seen by or on BL:- ...two swans. A swan's nest was seen, made completely of rushes was floating and was on about 2' 6" of water among the reeds.
H.H. Davis (1948) commented on their local abundance as being "frequent at the docks and reservoirs and not uncommon wherever there are suitable waters".
Recent Years (1974-2009)
A.H. Davis (1980) analysed the wildfowl counts and concluded that regular and maximum numbers of Mute Swan had fallen during the period 1971-1980 cf. counts for the period 1948-1962 (Atkinson-Willes, 1963). He also concluded that there was some evidence to demonstrate that part of the Blagdon population had moved to Chew.
At the national level, numbers increased during the 1950's but declined in the 1960's due to the severe winters early in the decade and more rapidly in the 1970's and early 80's due to lead poisoning from ingested fishing weights (Snow & Perrins, 1998). It is interesting to note, however, that the Mute Swan population index in Cranswick et al (1997) doesn't demonstrate the dramatic changes claimed by Snow & Perrins for the 70's and 80's. Additionally, Bland & Tully (1991) inferred there had been little change in the status of Mute Swan in the county since the previous atlas compiled in 1968-72, whilst Hammacott (1983), stated that 33 pairs bred in Avon (seven at BL) in 1983 cf. 23 in 1978.
There is no doubt the British population has increased steadily in recent years but the number attempting to breed at the lake remains fairly constant, even if the moult flock has indeed transferred to Chew Valley Lake.
Looking at the monthly maxima, there is a build-up in numbers resulting in a small peak during March and April probably related to local population movement by birds seeking nesting sites. Based on spatial requirements and suitable habitat, it seems that seven nesting pairs is about the limit that the lake can support. This may be reduced by bankside disturbance, particularly at the end of March when the birds are looking for somewhere to build their nests and fishermen are lining the banks at the start of the trout-fishing season. Nests are usually made in emergent bankside vegetation, though not always so, and The Island, Rugmoor Bay, Top End, Home Bay and Pipe Bay are often chosen. Unusually, a pair nested in the open on Peg's Point in 19xx and continued to brood despite anglers standing beside the nest to fish. Presumably the birds did not wish to abandon the nest once they had made such a commitment. Those birds that stay to breed will usually be sitting on eggs during April.
For a period of 6 - 8 weeks in summer, adult Mute Swans become flightless (they moult their flight feathers simultaneously), so seek a safe refuge where there is sufficient food. During this, the complete post-breeding moult, they have to take in enough energy to facilitate the replacement of upwards of 25000 feathers (Sibley, 2000). Indeed, the daily food requirement of moulting adults is quoted as between 3.6 and 4 kg of wet vegetable matter (Cramp & Simmons, 1978). Presumably, large numbers coincide with abundant, obtainable weed to provide them through the moult period.
Monthly maxima over the last ten years indicate an annual peak in July, if a moult herd of non-breeders gathers, although this peak may occur in June in some years e.g. 1997. I suggest that birds arriving in June that don't find conditions to their liking move on and this would account for the June peak. If they stay to moult their flight feathers then the number would remain constant from June onwards as they would be unable to leave the lake. The key months, therefore, for a moult flock to gather appears to be July into August when birds freely associate. Analyses of the moult flock numbers ought to be made for the months of July - August as a late autumn peak may occur in September and October that could unduly affect calculated averages. I have re-worked the data and will present it in due course.
The average number recorded for each decade probably reflects a combination of the size of the Mute Swan population and the water level of the lake. Numbers appear to have changed very little (to be confirmed).
In those years when the water level drops considerably (e.g. 1996, 2001 and 2002) there may be an autumn peak in October as small numbers making local movements seek to join the new families and those of the moult herd that don't move off during late August and September. Shallow water and abundant weed growth may provide ideal conditions for feeding, but numbers and distribution of newcomers can be severely affected by the presence of territorial breeding pairs with young, who defend their own food source vigorously. Mute Swans may fight to the death in exceptional circumstances and on 22 June 1997 I witnessed blood drawn by two cobs fighting for over twelve minutes in Holt Bay during which time a pen and four cygnets circled the affray. One cob tried to drown the other and there was an attempted rape or drowning of the pen. If the cygnets got too close to the fight they were occasionally struck by one of the cobs as well. This was quite a harrowing experience for the onlooker, never mind the birds involved!
Up-ending Mute Swans feed to a depth of about one metre (Ogilvie & Pearson, 1994) so can utilise food over a wide area of the lake in low-water conditions especially in the bays and at Top End. As the food supply dwindles, the swans move away and there are many occasions when none are present during the winter months. It would appear today that Blagdon Lake is of little significance as a wintering site. No doubt artificial feeding has a significant bearing on the whereabouts of large wintering gatherings e.g. Bristol Docks, though large herds gather on the Avalon Marshes in Somerset to feed on fields beside drainage rhynes. One pair has taken to feeding on Yeo Valley Farm fields on the south side of the lake during the winter in recent years rather than leave the lake altogether, perhaps to maintain their breeding territory.
Best Locations to View
There is no best location to view this species as they distribute themselves fairly evenly around the lake during the breeding season and tend to leave altogether in the winter during high water or freezing conditions.
Tundra Swan Cygnus columbianus (Ord, 1815)
Bewick's Swan C. c. bewickii (Yarrell, 1830)
(Scarce PM & WV, Oct. to Mar.)
Tundra (Bewick's) Swan, Slimbridge WWT © Nigel Milbourne, 2007
General Notes
Historical information suggests Bewick's Swans were rare in England and Wales in the 19th and early 20th centuries. During that period winter flocks occurred in the Netherlands, north-west Scotland and Ireland. Since the 1930's the migration route has shifted southward and increasing numbers have started to winter in the English midlands and south-west (cold weather influxes were said to have occurred in 1938-39 & 1955-56 - any local evidence?).According to Owen (1986) there are eight British Internationally Important sites and birds occur at satellite locations around each. There are two sites of International Importance locally; Slimbridge and the Somerset Levels, and birds could fly to Blagdon from either to feed (ringing proof that Slimbridge birds fly between BL and there is being established). Plants utilised by birds that don’t rely on food in artificial situations such as Slimbridge, include Marsh Yellow-cress Rorippa palustris, Pondweeds Potamogeton spp. and the Sweet-grasses Glyceria maxima and G. fluitans. When the water level and summer sunshine combines to produce luxuriant weed growth, Marsh Yellow-cress, several of the Pondweed species and Plicate Sweet-grass Glyceria notata all grow at Blagdon Lake (Myles et al, 2000).
Early Years (1898 - 1973)
The first definite record of Bewick's Swans visiting Blagdon Lake go back to the 12th January 1941 when four, two adult & two immature, were discovered at the Ubley end. It is likely that this referred to a family group because cygnets accompany their parents during their first winter and, on occasion, during their second winter as well (Lack, 1986).
Recent Years (1974 - 2003)
To be continued
Best Locations to View
Top End in autumn and winter low water conditions.
Whooper Swan Cygnus cygnus (Linnaeus, 1758)
(Accidental PM & WV, Nov. to Apr.)
Whooper Swan, Shetland Islands © Nigel Milbourne, 2008
9th February-8th April 1956 Adult B. King, A.C. Leach et al 20th-27th December 1961 2, not aged M.W. Seaford & T.B. Silcocks 14th January 1962 12, not aged B.K. Brooke 3rd-18th November 1962 4-20, not aged R.M. Curber, G. Sweet, J.W. Watkin & C. Lachlan 7th February 1965 4, not aged A.H. Davis, K.L. Fox, R.J. Senior & K.E. Vinicombe 7th December , 1974 8, 5 adults & 3 juveniles Julian T. Lovell
General Notes
To be continued
Early Years (1898 - 1973)
Whooper Swan records at Blagdon Lake are few and concentrated between 1956 and 1965. The record of 12 birds dated 14th January 1962 is best considered unsafe at present, due to the possibility of mistaken identity, unless more evidence comes to light.
Recent Years (1974 - 2003)
There has only been one additional record, in 1974, but more proof is required before counting it in the total. John Aldridge did some investigation and found the following information about this record: The observer was Julian T. Lovell and it was on 7/12/1974. The notes say 15.40 hrs. 8 birds, 5 ad & 3 juv. arriving lake from S. Moved across lake. 16.15 hrs. 2 imm & 1 ad. in company with above. Cl. 8/8, wind 4 S.W. Temp 8 degrees C, Dry. He must have been asked for more information by Paul Chadwick as there is a letter with supporting information. Julian stated that he had not considered Janowski's Swan as an alternative. I presume that the Janowski's Swan that Julian referred to is the larger, eastern Eurasian population of Bewick's Swan. I'm puzzled as to whether there were actually eleven birds after reading the above and feel that the likelihood of birds from the eastern Eurasian population flying over Blagdon to be barely worthy of consideration.
Best Locations to View
Top End in autumn and winter low water conditions, in all probability, though I have no detailed information on where the accepted records were seen. I haven't seen Whooper Swan at Blagdon Lake, so can't call on personal experience, though I wouldn't be entirely surprised to see some on adjacent farm fields if they were to visit at a future date.
American Wigeon Anas americana (Gmelin, 1789)
(Accidental vagrant)
1 |
27th January-5th February 1946 | Male | B.J. King |
General Notes
American Wigeon is one of the most numerous dabbling ducks in North America, with a population of about three million at the end of the 20th century. It is highly migratory, wintering in the USA, Central and South America and is a rare, but regular, visitor to Europe.
Early Years (1898 – 1973)
There has only been one record of American Wigeon, or Baldpate, at the lake. Bernard King found a drake on 27th January that stayed until 5th February 1946. On 2 nd March what was undoubtedly the same bird was noted at Cheddar Reservoir. What was likely to have been the same bird, given the species site fidelity, returned to Cheddar the following winter but was not, alas, observed at Blagdon on that occasion.
Recent Years (1974 -2003)
As the British Birds Rarities Committee no longer considers records of American Wigeon (since 1st January 2002) due to its regular occurrence, it is surprising that there have been no further instances of this species at Blagdon in the last fifty years. Identification of female and hybrid American Wigeon has been well documented (e.g. Brit. Birds 96: 2) and improved observer awareness has contributed to increased records in Britain.
Best Locations to View
The greatest number of new birds found on 'this side of the pond' occurs in October and November, but there is also a pronounced passage in spring. Provided that Eurasian Wigeon continue to winter at the lake, surely it is but a matter of time before another is found? Check the Eurasian Wigeon carefully at locations given for that species.
Green-winged Teal Anas carolinensis (Gmelin, 1789)
(Accidental vagrant)
1 |
18th December 1949 | Adult Male | B.J. King, D. Taylor |
2 |
6th January 1994 | Adult Male | M.G. Prince |
3 |
27th January 2002 | Male | Dr. P. Burrows |
General Notes
Since 1999, the Taxonomic Advisory Committee of the Association of European Records Committees and Taxonomic Sub-Committee of the British Ornithologist's Union Records Committee have been working closely together to produce advice on avian taxonomy in Europe. The BOURC, following recommendations from the taxonomic committees, perhaps controversially, split the Common Teal into the Eurasian Teal Anas crecca and Green-winged Teal Anas carolinensis. However, Jon L. Dunn, noted American ornithologist, told me that he thought the taxonomic split was a little suspect and he intimated that the decision ought, perhaps, to be reviewed. At the time of writing, however, I shall follow the BOURC line in considering Green-winged Teal to be a full specie.
Early Years (1898 - 1973)
Bernard King and D. Taylor found an adult male among Eurasian Teal on 18th December 1949. The bird was viewed with a telescope at fifty yards' range. The following characters were noted - white, vertical breast-band immediately fore of the wing; absence of white horizontal band above wing; ill-defined and scarcely perceptible creamy-white line separating chestnut crown from green eye-band; warmer ground-colour of lower breast. Peter Scott reported that all captive Green-winged Teal in the British Isles were permanently pinioned at the time, so the bird was considered to be a genuinely wild visitor, making this the first record for the district and for the then County of Somerset.
Recent Years (1974 - 2003)
At Chew Valley Lake, a male returned for it's sixth consecutive winter from 3rd October 1993 until 22nd January 1994, however, on the 6th January 1994 it was seen at Blagdon Lake by M.G. Prince; thus becoming the second site record. On 27th January 2002 Dr. Paul Burrows reported a male briefly at Top End, but despite extensive searching during the remainder of the afternoon and next day it was not seen again (I consider this record to be unproven but include it as it was accepted by the AOG Records Committee).
Best Locations to View
Any shallow margins especially where there is emergent vegetation e.g Top End and Rugmoor Bay during Autumn and Winter.
Spotted Crake Porzana porzana (Linnaeus, 1766)
(Accidental PM, mainly in Sep.)
1 |
12th-15th September 1996 | One | K.E. Vinicombe |
2 |
13th-15th September 1996 | One | J.P. Martin et al |
General Notes
This species occurs annually at Chew Valley Lake at the end of the 20th Century.
Early Years (1898 – 1973)
There were no records in the early years.
Recent Years (1974 - 2003)
Two records of unidentified crakes noted in the 1980’s may have been this species, but it wasn’t until 1996 that the first Spotted Crake was found by Keith Vinicombe. Amazingly, John Martin saw two birds the following day that stayed until the 15th September.
Best Locations to View
I cannot give any suggestions as to the best places to look for Spotted Crakes as I have yet to find one in the many places I've looked since the first records. Access to view emergent vegetation is very limited at Blagdon so the likelihood of finding crakes is somewhat restricted.
American Golden Plover Pluvialis dominica (Statius Muller, 1776)
(Accidental vagrant)
1 |
1st-2nd November 2003 | Juvenile | N.R. Milbourne, R. Mielcarek et al |
General Notes
American and Pacific Golden Plovers were considered to be races of 'Lesser' Golden Plover and weren't split by the BOU until 1986 because it was thought that the two races inter-bred. The first accepted British record of American Golden Plover was on Fair Isle, Shetland in 1956.
Early Years (1898 – 1973)
There are no historical records of this species at Blagdon Lake. Indeed, the first for the Bristol area occurred only as recently as October 1994 at Chew Valley Lake.
Recent Years (1974 -2003)
I found the only bird known to have visited Blagdon Lake early in the morning on the 1st November 2003. After about an hour of careful observation I had noted the grey underwing on four occasions and I put out the word of a Lesser (probable American) Golden Plover Pluvialis dominica present off Bell's Bush with European Golden Plover Pluvialis apricaria. Richard Mielcarek arrived and he and I were able to clinch the identification and age the bird as a juvenile. Although appearing to have flown off at 1215 hrs the bird returned later and was seen by many observers before flying off again at 1455 hrs. It was present again the following morning 2nd November and relocated for the last time at Yoxter on the Mendip plateau by Simon Isgar on 5th November.
Best Locations to View
Check waders, especially if any European Golden Plover flocks occur during the autumn migration period at Top End.
Ring-billed Gull Larus delarwarensis (Ord, 1815)
(Accidental vagrant)
Ring-billed Gull, 2nd-winter, Chew Valley Lake © Nigel Milbourne, 2006
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
1 |
9th May 1998 | 2nd -summer |
N.R. Milbourne |
General Notes
This American species is relatively new to Britain with the first being found at Blackpill, Swansea in March 1973. It seems quite likely that others will have occurred in Britain before then, but they were not identified as Ring-billed Gulls. In support of this supposition, there was a record of a bird in Spain during 1951 and in Germany as long ago as 1968. The first for the Bristol area was found at Chew Valley Lake in March 1980, with another eight days later at the same venue. The species is almost annual in the Bristol area today.
Early Years (1898 – 1973)
There are no early records of this species at the lake.
Recent Years (1974 -2003)
Rare gulls seem to be just that at Blagdon Lake, no doubt because there is no sizeable roost other than Black-headed Gulls. So, I was quite surprised to come across a Ring-billed Gull sitting on the water just off Green Lawn on 9th May 1998; itself an unusually late spring occurrence. The view was brief, but the gull was found later the same day at Barrow Tanks and aged as a second summer. Its immaturity might account for the late migration date as second-year birds are said to be more leisurely in their migration north than adults (Vinicombe, 1985). Given the frequency with which Ring-billed Gulls are found at Chew Valley Lake, another is long overdue at Blagdon.
Best Locations to View
Ring-billed Gulls tend to be loners on this side of the Atlantic. They often find sites where they can obtain easy pickings during the winter to which they remain faithful over a number of years, or, they are seen on spring migration at well-established gull roosts. As there is very little feeding of birds at Blagdon, the chances of one wintering at the site are minimal, so the best opportunity is likely to present itself between lunchtime and late afternoon from February to April when passage birds may drop in to bathe and rest.
Bibliography
Atkinson-Willes G. National Wildfowl Counts 1952-1954. The Wildfowl Trust, Slimbridge.
Atkinson-Willes G.L. (Ed.) 1963. Wildfowl in Great Britain. London.
Bland R.L. & Tully J. 1992. Atlas of Breeding Birds in Avon, 1988-91. Gloucester.
Cramp S. & Simmons K.E.L. (eds.) 1978. Handbook of the Birds of Europe, the Middle East and North Africa. The Birds of the Western Palearctic. Volume I. Oxford.
Cranswick P.A., Waters R.J., Evans J. & Pollitt M.S. 1995. The Wetland Bird Survey 1993-94: Wildfowl and Wader Counts. Slimbridge.
Cranswick P.A., Waters R.J., Musgrove A.J. & Pollitt M.S. 1997. The Wetland Bird Survey 1995-96: Wildfowl and Wader Counts. Slimbridge.
Davis A.H. 1980. A Review of some Waterfowl at Blagdon Lake, 1971-1980. Bristol Ornithology, 13, pp. 94-96.
Davis H.H. 1948. A Revised List of the Birds of the Bristol District. Reprinted from the Proceedings of the Bristol Naturalists' Society, vol. XXVII, part IV, pp. 225-268. 1947.
Davis H.H. et al. 1969. Somerset Birds 1968, p. 2.
Delany, S. 1993. Introduced and Escaped Geese in Britain in Summer 1991. Brit. Birds 86: 592-599.
Gregory, R.D., Wilkinson, N.I., Noble, D.G., Robinson, J.A., Brown, A.F., Hughes, J., Procter, D., Gibbons, D.W. & Galbraith, C.A. 2002. The population status of birds in the UK, Channel Islands & Isle of Man: an analysis of conservation concern 2002-2007. British Birds, vol. 95, No. 9, Sep. 2002.
Hammacott H.R. 1984. BTO Mute Swan Census 1983. Avon Bird Report 1983, p. 46.
Lack, P., 1986. The Atlas of Wintering Birds in Britain and Ireland, Staffs.
Myles, S. (Ed.) 2000. The Flora of the Bristol Region, Berks.
Ogilvie M. & Pearson B. 1994. Wildfowl. London.
Owen M. 1977. Wildfowl of Europe. London.
Palmer E.M. & Ballance D.K. 1968. The Birds of Somerset. London.
Palmer P. 2000. First for Britain and Ireland 1600-1999. Chelmsford.
Rowell, H., Ward, R., Hall, C. & Cranswick, P. 2004. The Naturalised Goose Survey 2000. Wildfowl and Wetlands Trust Research Report, Slimbridge.
Sibley D. 2000 . The North American Bird Guide. Sussex.
Smith, Cecil 1869. The Birds of Somersetshire. London.
Snow D.W. & Perrins C.M. 1998. The Birds of the Western Palearctic Concise Edition. Volume I. Oxford.
Vinicombe K.E. Ring-billed Gulls in Britain and Ireland, Brit. Birds 78: 327-337, July 1985.
Vinicombe K. & Cottridge D.M. 1996. Rare Birds in Britain and Ireland. A Photographic Record. HarperCollins Publishers, London.