This paper continues the preliminary listing of British & Irish records of

Transcription

1 Scarce migrants in Britain and Ireland Part 2. Numbers during : gulls to passerines P. A. Fraser and J. F. Ryan This paper continues the preliminary listing of British & Irish records of 'sub-rarities': mostly those species which were formerly assessed by die British Birds Rarities Committee* but became too frequent still to be classed as rare birds, and some others which fall into the same general category. This scries of papers follows the patterns of collation and analysis of records of less-common migrants and semi-rarities started by Dr J. T. R. Sharrock {Brit. Birds 62: , ; 63: 6-23, ; 64: -113, ; 65: , ; 66: 46-64, ; collected together in Scarce Migrant Birds in Britain and Ireland, 1974) and continued by J. N. Dymond, P. A. Fraser and S.J. M. Ganllett (Rare Birds in Biitain and Ireland, 1989). As emphasised in the introduction to part 1 (Brit. Birds 85: ), all the records included in this analysis have been documented by the observers and then assessed and accepted by the relevant county, regional or national records committee. We urge all observers of scarce species to submit full details to the relevant county or regional recorder. Undocumented, hearsay reports (even if notified by well-known observers) have no value and no place in the permanent record for posterity. Group 7. Gulls and skuas Sabine's Gull Lams sabini Yellow-legged Gull L. cachinnans Ring-billed Gull L. dehwareruvi Long-tailed Skua Stercorarius longkaudiis , , , , The work of the British Birds Rarities Committee is sponsored by Carl eiss (Oberkochm) IM ft*. Hints (17: 605-«I2, December IM4 t)l) J

2 606 Scarce migrants in Britain and Ireland The 'Great Storm' of October 1987 will be remembered for many years by those in southeast England for displacing unprecedented numbers of Sabine's Gulls from the Bay of Biscay into parts of the country where they had, hitherto, been very rare {Brit. Birds 82: ). It may be of interest to note, though, that, even without these records, 1987 would still have been the second-best year on record. Some 247 were recorded before 10th October, bettered then only by 1983 (321). We have estimated that, some 310 were recorded after this date; tiiis assumes that all tfiose seen after 18th October were individuals moving on from their initial sites. It is not impossible that the figure could be as high as 550, the most important factor being the level of duplication of records in Hampshire and the Isle of Wight, where flocks of 50 were seen on several occasions. Figs. 1, 2 & 3 show the numbers present on, respectively, 16th, 17th and 18th October Of the 'storm-birds' aged, 76% were adults. The year 1988 was also exceptional for this species, although not receiving the publicity of Records in 1988 occurred in more traditional areas: Cornwall had 192 and Go. Clare 74. The vast majority of records of Yellow-legged Gulls are in the Soudieast (figs. 4 & 5, page 608). Papers on the identification of this and related species, both in a British context and on a West Palcarctic scale, are in preparation for publication in British Birds. The apparent increase in numbers of Ring-billed Gulls between 1989 and 1990 is probably, at least in part, an artifact, as once a species is removed from the BBRG list it becomes increasingly difficult to distinguish newly arrived individuals from returning and wandering birds, which would not be counted (as new occurrences) in the BBRC system. Future totals, as is generally the case with scarce migrants, will reflect the number of individuals arriving in Britain & Ireland during the course of a year, irrespective of whether they have already passed through in previous years. There has been a dramatic increase in the numbers of Long-tailed Skuas recorded off our shores in recent years. Huge numbers were recorded in 1988 {Brit. Birds 84: ), but the totals in even the lesser years of 1986, 1987, 1989 and 1990 were exceeded by only one year prior to Then came 1991, with nearly three times as many as in the entire period {Brit. Birds 85: ). Group 8. Near-passerines European Bee-cater Mcvops apvxskr Hoopoe Upupa epops Wryneck Jynx ttm/iiilk Records of European Bee-eaters in Britain and Ireland ceased to be published in the British Birds Rarities Committee annual reports after 1990, when the species exceeded the criteria used to define a national rarity. In 1991, there was a major influx into eastern England during late June and July. We have assumed that three records of five seen in Essex and twice subsequently in Kent referred to the same flock.

3 Scarce migrants in Britain and Ireland 607 Fig th October 1987 Fig th October 1987 Fig th October 1987 Figs Distribution of Sabine's Gulls Lams sabini on (1) 16th October 1987, (2) 17th October 1987, and (3) 18th October Note different scales of abundance on each map The pattern of records of Hoopoes continues much as before: the average was 137, compared with 125 for The years 1958 (224) and 1968 (240) have yet to be bettered.

4 608 Scarce migrants in Britain and Ireland Fig. 4. July-September Fig. 5. January-March Figs. 4 & 5. Distribution of Yellow-legged Gulls Lams cachinnans (4) in early autumn (July- September) and (5) in early winter January-March) Note different scales of abundance on each map Most Wrynecks occur in autumn (fig. 6). The mean annual total for is 255. The pattern is similar to that of Ortolan Bunting Emberiza hortulana (see group 11), which has a similar breeding range, but the striking difference is the large number of inland records of Wrynecks (figs. 7 & 8). This may be due to the birds' feeding habits, which may bring them into back gardens, but raises the question of how many odier European drift migrants go undetected away from the coast. Group 9. Pipits and larks Horned I^ark Eremophila alpestris Richard's Pipit Anthus novaeseelandia Tawny Pipit A. campestris The Horned Lark figures are provisional and will be revised in a more detailed analysis of this species. The mean annual total of Richard's Pipits rose to 92 during , from 57 during , but this is not a statistically significant increase since, as with many Siberian migrants, the numbers reaching Western Europe vary enormously from year to year. The 151 in 1988 is only three short of the 1968 record (though there were many fewer observers then). Tawny Pipits have also shown a slight, but not significant, increase. The mean was 40, compared with 30 during

5 Scarce migrants in Britain and Ireland 609 Fig. 6. Seasonal spread by weeks of Wrynecks Jynx torquilla during Fig. 7. Spring Fig. 8. Autumn Figs. 7 & 8. Distribution of Wrynecks Jynx torquilh (7) in spring and (8) in autumn Group 10. Warblers Aquatic Warbler Acrocephalus paludicola 27 Icterine Warbler Hippolais kterina 87 Melodious Warbler H. polyglotta 38 Barred Warbler Sylvia nisoria 140 Pallas's Leaf Warbler Phylhscopus proreguhis w 11 Yellow-browed Warbler P. inornatus

6 610 Scarce migrant in Britain and Ireland The numbers of Aquatic Warblers found each year depend almost entirely on the ringing effort in the reedbcds along the south coast of England. Totals in none of the recent years have reached the 99 recorded in Annual totals of Ictcrine Warblers were on a plateau during , with a mean of 85, compared with during The totals for 1990 and 1991 were the lowest since The spring total of 31 in 1988 was the second-highest, but, although dwarfed by the 60 in spring 1984, neither year compared with the invasion of 1992, when 165 arrived between the last week of May and the last week of June. Melodious Warbler records show little annual variation. The mean was 34, compared with a mean of 37. Numbers of Barred Warblers fluctuate grcady from year to year, though are normally between 100 and 200. The mean was 108, compared with 135 for The years 1988 and 1987 were the second-best and third-best for Pallas's Leaf Warblers, the peak year having been 1982 with 127. The sudden jump in the numbers of Yellow-browed Warblers reaching Britain & Ireland which occurred in 1984 has been consolidated, with approaching 800 in 1988 and then around 300 annually during This species is now being found in winter nearly every year. Have wc witnessed a shift in migration pattern of a portion of the population? And, if so, why has this shift occurred? Group 11. Other passerines Bluethroat Luscinia svecica 61 Red-breasted Flycatcher Fkedula pan/a HI Golden Oriole Oriulns oriofas 66 Red-backed Shrike Lanius collurio 167 Great Grey Shrike L. exaibitor 126 Woodchat Shrike L senator 26 European Serin Serinus smnus 40 Common Roselinch Carpodacm aylhrmus 71 Ortolan Bunting Embmza hortuhna There were two major Bluethroat falls on the North Sea coast, in the springs of 1987 and In 1987, some 187 were recorded during 22nd-27th May. The 1988 fall occurred some ten days earlier, beginning on 11th and peaking on 14th; some 146 were recorded during llth-20th May. In both cases, all those subspccifically identified were of the red-spotted nominate race. In 1987, five were ascribed to the white-spotted race cjanecuh (all during 31st March to 5th April), and two others at die same time were claimed as the race magna (which breeds in the Caucasus and Iran), but which is not yet on the British & Irish List (some Iberian Bluethroats look very similar). The mean annual totals of Red-breasted Flycatchers were 103 during , compared with 91 during ; annual totals have been unremarkable. Golden Orioles appear still to be increasing: the mean was 105, and only one year (1991) had fewer than the mean of 60. (We have endeavoured to include only migrant records in those counties which have a breeding population.)

7 Scarce migrants in Britain and Ireland 611 Fig. 9. Seasonal spread by weeks of Red-backed Shrikes Lanius collurio during Fig. 10. Spring Fig. 11. Autumn Figs. 10 & 11. Distribution of Red-backed Shrikes Lanius collurio (10) in spring and (11) in autumn Red-backed Shrike records, like diose of Wrynecks, were not analysed for Rare Birds in Britain and Ireland (1988), so are displayed here (figs. 9-11). The annual mean was 227, making Red-backed Shrikes somewhat rarer than Wrynecks (perhaps much rarer, for the shrike is much less likely to be overlooked). The years 1988 and 1992 were both marked by substantial spring influxes, 263 in 1988 and 228 in In contrast, 1992 produced only 40 Red-backed Shrikes in August and September, whereas 1988 saw 158 autumn migrants. The Great Grey Shrike figures like those for Horned Lark are provisional, pending a more detailed analysis of exactly how many individuals are recorded here as migrants and as winter visitors.

8 612 Scarce migrants in Britain and Ireland For Woodchat Shrike, the year 1991 stands out as poor, the worst since 1972 (when there were also seven) and in the past 35 years exceeding only the lean spell of (when there were four, three and two in successive years). The 27 in 1988, however, was an all-time high. The European Serin bred sporadically in southern England during the 1970s and 1980s, but has not consolidated diis tenuous foothold. It is a difficult species to assess, as many coastal watchpoints frequently report long series of observations in which it is obviously very difficult to estimate the number of individuals involved. The recent upsurge of records of Common Rosefinch, especially in spring, has been one of the ornithological events of the last few years. We all wait with interest to see whether the species will become firmly established, or whemer, Eke the preceding species, it will be added to the long list of diose which have just failed fully to colonise from the Continent. A paper on the spread of the Common Rosefinch is being prepared by D. I. M. Wallace for publication in British Birds, but the records from the county bird reports already show die unprecedented number of spring arrivals in Future plans Now that the basic data have been assembled and the annual numbers summarised (in parts 1 and 2), we shall be looking in much more detail at the patterns of individual species and groups of species. We shall also be updating the database constandy and publishing revised figures at regular intervals. Acknowledgments The records published by the network of county, regional and national reports, stemming from the collection, assessment and collation of observers' observations by their recorders and report editors, make it practicable to monitor the changing fortunes of rare and uncommon birds in Britain & Ireland. We thank all those who by their labours make our analyses possible. P. A. Fraser, 12 Redknd Court Road, Bristol BS6 7EQ_ Dr J. F. Ryan, Lynwood, Landeryon Gardens, Penzance, Cornwall TR18 4JN