British Birds Report on Rare Birds in Great Britain in 1997

British Birds Established 1907; incorporating 'The Zoologist', established 1843 Report on rare birds in Great Britain in 1997 M. J. Rogers and the Rarities Committee with comments by Grahame Walbridge and Andy Stoddart This is the fortieth annual Report of the Rarities Committee and, once again, it demonstrates the vital roles of the Report and the Committee. This is, perhaps, not surprising, as the Committee is the only body that liaises with the full network of County Bird Recorders (to whom we give thanks) and produces the only report for which detailed descriptions are independently assessed by a panel of democratically elected individuals. In an average year, we process about one thousand records, and our estimate for this year is that only 35 reasonable claims have not yet been submitted to the Committee for scrutiny. Two notable records were not submitted in time to be dealt with in this Report: a Great White Egret Egretta alba (possibly of the Nearctic race), in Northamptonshire, in November-December, and a Veery Catharus fuscescens, in Devon, in May. A further 20 for 1997 and earlier years arrived too late to be considered for this Report. We feel that, whilst it is not ideal, a late- submission or non-submission rate of 5% is to be expected. The role of the Committee is clear. We are to assess, from information provided to us, the suitability of records of rare birds to be included in the national rare-bird archive. The specifics of this task create one of our major problems. Because we are judging the records for posterity, we have to base our decisions on the information that is provided to us, so that, if the records are reappraised in future, the logic of our decision-making is obvious. Whilst this may appear self-evident, it was not necessarily the case in previous generations. Recent reassessments of older records have sometimes proved impossible, as the documentation lacked sufficient detail on which to make a judgment. Decisions often seemed to have been based on 'observer criteria' only, that is whether the Committee, at the time, felt that the observer 'would know this bird if he or she saw one', and not on the standard of description. This has been one of the major reasons why reviews of old records have taken so long. Currently, we strive to reach a balance, with knowledge of the observer used alongside the quality of the description. The ever-improving standard of rare- bird photographs has made this much easier, although it has also caused some problems. Today, it is a comparatively rare event to see someone taking field notes at a 'twitch'; why should you, when there are superb photographs for sale or published for all to see in the birding glossies? In addition, if the initial [Brit. Birds 91: 455-517, November 1998] © British Birds Ltd 1998 455 456 Rogers el al.\ Rare birds in Great Britain in 1997 description from the finder is not sufficiently detailed, we can usually get further descriptions from other observers present at a twitch. Our problem comes more with birds that are seen by a very few or only one observer, and especially when the bird is not a 'mega-rarity'. Because of the twitching network, it is possible for a birder to see three or four individuals of some species—e.g. Laughing Gull Larus atricilla or Desert Wheatear Oenanthe deserti—in a year. Thus, it is easy to understand why some people feel that they need to supply a less-than-complete description; but, if there are no photographs or supporting descriptions, the Committee often has to judge the record to be unproven. In this Report, we not only detail those records which we feel are acceptable, but also list, in Appendix 2, those records which we feel do not meet the standards required for acceptance. In the majority of cases, the Committee considers that the identification was probably correct, but that the documentation, usually through no fault of the observers, is not sufficient to prove the record beyond reasonable doubt. Whilst the level of detail required for some species is not great, for others, such as the 'peeps', a full and very detailed description is required. The Committee takes all records seriously; none is discarded out of hand (although flocks of Nutcrackers Nucifraga caryocatactes coming to bird-tables in summer are an exception) and some take an enormous amount of work (see Brit. Birds 91: 180-184). In a small number of cases, we feel that a mistake in identification has been made, and, in an even smaller number of instances, we wonder whether we are being deliberately misled. The kudos of finding rare birds is now such that one can understand the desire to 'find' a rarity, and sometimes this may lead to a claim of a bird that really has not been properly identified. This is one of the reasons why we prefer descriptions which include details of circumstances of the observation. On most occasions, we empathise with the observer and understand how some feature has been missed. Sometimes, however, we feel that it is impossible to have got the level of detail submitted from the reported views. We are also very cautious about observers with a high proportion of single-observer records. We are aware that geographical and social circumstances are such that some people are more likely to find rare birds on their own, but this does not account for the startling rates which we see with some observers. Britain is a small country, and there are many birders out there. Rare birds are a long way off course, and many stay a few days after they have been found. Many observers in remote areas or on inaccessible islands find birds that others get to see, and it is rare for a birder to have a single-observer record rate of more than 50% (in fact, most of the Committee have a single-observer rate of between 5% and 20%). It sets alarm bells ringing when an individual's profile is well outside this range, especially if, as is often the case, it is accompanied by a gradually increasing scarcity of the species claimed in single-observer records. There is no bias against such records individually, but we do have a policy of watching any patterns closely and reviewing the observers' past records on a regular basis. Appendix 4 contains a list of submissions which have been pended for further information either from the observers or from outside experts or other British Birds, vol. 91, no. 11, November 1998 457 sources. Whilst we understand the desire for a speedy decision to be reached, we can work only with the material at hand. A less-than-cornplete description of a good bird might result in its not being accepted. If the record is pended and further information is forthcoming, the correct decision can be made. Under these circumstances, it is in the interest of the observers, as well as being vital to the integrity of the scientific archive, that the record is delayed. We continue to work in close co-operation with the BOU Records Committee, which is currently examining records of Canvasback Aythya valisineria, in Kent in 1996 and in Norfolk in 1997; Lesser Sand Plover Charadrius mongolus, in West Sussex in 1997; and Iberian Chiffchaff Phylbscopus brehmii, in Greater London in 1972 and in Scilly in 1992. All have been accepted by the BBRC. We are indebted to the many photographers who have sent us a total of over 500 prints and transparencies for circulation during record assessment (see The Carl Zeiss Award, Brit. Birds 91: 406-408), particularly Dr Iain H. Leach, George Reszeter and Steve Young, who supplied large numbers of high-quality prints, and all those whose work especially helped the Committee in its deliberations (e.g. Gary Bellingham, whose photograph of the Cumbrian Purple Gallinule Porphyria porphyrio showed, despite assertions to the contrary by some observers, that this bird had missing primaries on at least one wing). Whilst the BOU Records Committee has, at the request of the Irish Rare Birds Committee, ceased to maintain a British & Irish List, now publishing only a British List, we have agreed, following representation from the Northern Ireland Bird Records Committee, to continue to provide statistics for Britain and Ireland combined. This makes zoogeographical sense, whereas listing of data separately for the United Kingdom and for the Republic of Ireland would not. This arrangement will, of course, be reviewed periodically, but, for the time being, the method of calculating the annual statistics is the same as that used for the past 40 years (see pages 458-459). The Committee continues to examine ways of streamlining its system, and is currently in the throes of a modernisation process that, amongst other things, will allow the speeding-up of circulations of difficult records. We have developed a network of international experts who have agreed to act as advisors to the Committee. All are able to receive information through the Internet, including scanned photographs and drawings. We wish to thank those who have agreed to help us in this way, including Per Alstrom, Arnoud B. van den Berg, Louis Bevier, Ned Brinkley, Geoff Carey, Alan Dean, Jon Dunn, Jim Enticott, Dick Foreman, Kimball Garrett, Erik Hirschfeld, Hannu Jannes, Al Jaramillo, Paul Lehman, Bruce Mactavish, Michael O'Brien, Dennis Paulsen, Ron Pittaway and Will Russell. We should also like to thank Ned Brinkley, Pete Clement, Dick Foreman, Erik Hirschfeld, Paul Holt, Gabor Magyar, Anthony McGeehan, Bruce Mactavish, Klaus Mailing Olsen and Keith Vinicombe for their input on difficult records this year, and Keith Naylor for his extensive practical assistance in respect of historical data.

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