Report on scarce migrant birds in Britain in 1998 Peter A. Fraser, Peter G. Lansdown and Michael J. Rogers Ernest Leahy Horned Larks Eremophila alpestris ABSTRACT For this fourth annual report, covering 1998, information on assessed and accepted records of scarce migrant birds was supplied, sometimes in advance of publication in their local bird reports, by County Bird Recorders. There were all-time record numbers of two species in 1998: Cory’s Shearwater Calonectris diomedea and White Stork Ciconia ciconia. Furthermore, Balearic Shearwater Puffinus mauretanicus, Wryneck Jynx torquilla, Horned Lark Eremophila alpestris and Great Grey Shrike Lanius excubitor each registered the highest totals since we started to monitor their occurrences annually; and numbers of Purple Herons Ardea purpurea and Red-backed Shrikes Lanius collurio in 1998 were the joint-highest and highest respectively during the last ten years. In 1998, no species registered its lowest-ever annual total, nor was any species’ annual total the lowest during its study period. Fewer Tawny Pipits Anthus campestris,Savi’s Warblers Locustella luscinioides, Aquatic Warblers Acrocephalus paludicola and Melodious Warblers Hippolais polyglotta were seen in 1998, however, than in any other of the last ten years. 588 © British Birds 93: 588-641, December 2000 Fraser et al.: Report on scarce migrant birds in Britain in 1998 his is the fourth annual report on their ready co-operation, this report would scarce migrant birds in Britain. It not have been possible. We are also very Tfollows the same format as the third grateful for the assistance and advice given report (Brit. Birds 92: 618-658), which by Jon Green, Dr Peter Knight and the Welsh covered 1997, but contains one fewer Ornithological Society. species: Red-crested Pochard Netta rufina is omitted. Systematic list Only records that have been assessed and Interpretation of the statistics used and fully accepted by the appropriate local, quoted in the species accounts should take regional or national record panels have been into consideration the following: included in this report. Every year, the Since 1958, the increased number of assembly of data, which includes the record- observers and their collective enhanced assessment process, takes much longer for knowledge, improved mobility and greater some counties than for others. As a result, amount of time spent in the field must, in and despite the willing and enthusiastic co- some part, be responsible for the increase in operation of nearly all of Britain’s county the recorded numbers of some scarce bird recorders and their assistants, these migrants. national reports on scarce migrant birds Known breeding birds (e.g. Red-necked inevitably have to be published well after the Phalaropes Phalaropus lobatus) have been year in question. Even then, most or all excluded, except in the case of Savi’s Warbler records from a few counties and sub-coun- Locustella luscinioides. ties are not included; this report lacks most Individuals remaining from one year to or all of the relevant 1998 records from the next (e.g. overwintering Surf Scoters Caithness, Hertfordshire and Staffordshire. Melanitta perspicillata) have been counted Statistics have been updated for previous only in the year of their arrival. years as they have become available, even if Returning individuals (e.g. Ring-billed this was after publication of the report on Gulls Larus delawarensis) have, where pos- the year in question. Readers should note sible, been counted only in the year of their that an extra 350 records have been added arrival. for 1997 and earlier years, and that many of Known escapes from captivity (e.g. some the statistics have been revised accordingly. White Storks Ciconia ciconia) have been This report covers England, Scotland, excluded. Wales and the Isle of Man. We should very Statistics for some species for 1998 and, much like to include records for the whole to a lesser degree, for earlier years are incom- of Ireland, as well as for the whole of Britain, plete because of the unavailability of data in future reports, in order to be able compre- from some counties. hensively to study the pattern of records in Because this report contains no records the entire natural zoogeographical area of from Ireland for 1998, past Irish records have Britain & Ireland. At the time of writing, all been excluded from the statistics in all but a Irish records have been entered into the very few cases, so that a true comparison database up to and including 1997, so it can be made with previous years. Except would be a relatively straightforward task where captioned to the contrary, the his- thus to extend the scope of the report, tograms also exclude Irish records. which remains our eventual aim. The numerical scales of the maps have been calculated logarithmically, not linearly Acknowledgments as in previous reports. This better differenti- First and foremost, the three authors wish to ates between low numbers, and highlights thank most sincerely the county and regional single records, but underplays particularly recorders and their assistants for providing high numbers, compared with the arithmetic such detailed information for 1998 and for scales used in the maps in the previous three supplying additional records for past years reports. where relevant. Without the recorders and British Birds 93: 588-641, December 2000 589 Fraser et al.: Report on scarce migrant birds in Britain in 1998 Cory’s Shearwater Calonectris diomedea Numbers of individuals in 1958 – 1997 Number of Number of individuals individuals 1958 – 1992 1993 1994 1995 1996 1997 in 1998 in 1958-98 7281 1747 56 374 75 1731 5114 16378 Annual maxima 1958 – 1998 Annual averages 1958 – 1998 Annual average 1998 1980 1993 1997 58 - 69 70 - 79 80 - 89 90 - 98 1958-98 5114 2851 1747 1731 14 16 453 1280 399 An estimated 5,114 Cory’s Shearwaters were seen in Britain in 1998: 4,771 in Cornwall, 288 in Scilly,28 in Devon, seven in East Yorkshire, four in Fife, three in Kent and one or two in a further seven counties, as illustrated in fig.1. Of the 5,109 individuals for which exact dates are available, ten were seen during 11th-16th July, 294 during 21st-25th July, 17 on 30th July, ten during 6th-16th August, 30 during 21st-28th August, 4,742 during 4th-17th September and five during 23rd September to 3rd October, with one on 25th October, at Cley, Norfolk. It seems likely that a large number of birds were displaced north on strong, warm southerly winds generated by a deep depres- sion that arrived to the west of Ireland in early September.The most productive locality in 1998 was Gwennap Head, Porthgwarra, Corn- wall, where there were daily totals of 3,500, 256 and 60 on 5th, 6th and 7th September respectively, and 198 and 78 on 21st and 22nd July. Addition- ally, there were 400 on 6th Sep- tember at Bass Point, Cornwall, 270 on 6th September at St Agnes, Scilly, 156 on 6th September at Killigerran Head, Cornwall, and 50 on 5th Sep- tember at Pendeen Watch, Cornwall. Fig. 1. Distribution of Cory’s Shearwater Calonectris The highest daily totals were 3,555 diomedea in each county in Britain in 1998. Note the on 5th September and 1,102 on 6th exceptionally high number in Cornwall. September. The total of 5,114 Cory’s Shearwa- ters in Britain in 1998 was by far the highest annual total since national record collation began in 1958; indeed, the number in 1998 equates to over 45% of the total during 1958-97. Cory’s Shearwater is comfortably the most numerous species to appear in this report. Never- theless, we shall continue to include it, as there are still relatively few records per year, even if some of those are of large numbers of birds, and the species is still very rare away from the tradi- tional sea-watching spots in the Southwest. 590 British Birds 93: 588-641, December 2000 Fraser et al.: Report on scarce migrant birds in Britain in 1998 Balearic Shearwater Puffinus mauretanicus Numbers of individuals in 1986 – 1997 Number of Number of individuals individuals 1986 – 1992 1993 1994 1995 1996 1997 in 1998 in 1986-98 3181 959 834 955 1636 1479 2024 11068 Annual maxima 1986 – 1998 Annual averages 1986 – 1998 Annual average 1998 1996 1997 86 - 89 90 - 98 1986-98 2024 1636 1479 314 1090 851 Of the estimated 2,024 Balearic Shearwaters recorded in Britain in 1998, 967 were in Cornwall, 538 in Devon, 259 in Dorset, 66 in Pem- brokeshire, 41 in Kent, 30 in Sussex, 24 in East Yorkshire and 21 in Scilly, with 16 or fewer in a further 15 counties, as illustrated in fig. 2. Exact dates are available for only 648 individuals, while the month of occurrence is known for 1,748 birds. Of these, singles were seen on 3rd January, off Hope’s Nose, Devon, 5th January, at Dungeness, Kent, and 17th January and 21st March, at Flambor- ough Head, East Yorkshire; there were three in May, 19 in June, 351 in July, 289 in August, 802 in September, 257 in October, 20 in November and Fig. 2. Distribution of Balearic Shearwaters Puffinus three in December, including singles mauretanicus in each county in Britain in 1998. Note the on 25th, at Hope’s Nose, and on 29th, prominence of the Southwest, in particular Cornwall, at Strumble Head, Pembrokeshire. Devon and Dorset. Balearic Shearwater continues to increase in Britain: more were recorded in 1998 than in any other year since national record col- lation began in 1986, and the three highest annual totals occurred in the last three years and the six highest were in the last six years.