THE PASSAGE OF WADERS AND TERNS THROUGH WEST SUFFOLK A . J . LAST
Introduction DĂœRING the past decade a considerahle effort has been put into collecting sufficient data to permit an analysis of the movement of waders and terns through West Suffolk. Such an analysis is the subject of the present paper.
Methods For the purpose of this paper, West Suffolk is defined as that part of Suffolk to the west of a line from Redgrave in the north to Bures in the south. T h e paper is based on data extracted from the Suffolk Bird Reports 1950-74, supplemented to a large extent by personal observations (up to 1975) and by the records of those observers hereinafter mentioned. For the terns and the less common waders, all records (both spring and autumn) during the years 1950-75 were used. For the more numerous waders, all spring records during the period 1950-75 were reviewed, but the only autumn (June 16thOctober 31st) records taken were those from two localities, namely the Bury B . F . Ponds (i.e., the British Sugar Corporation's settling ponds at Bury St. Edmunds) and Livermere Lake, during the eight seasons 1966-71 and 1974-5 (hereinafter referred to as 'eight seasons'). T h e totals for the eight seasons are shown in the Table. Intensive coverage was attained in the four autumns of 1967, 1968, 1970 and 1971, when at least one visit per three days was made to either of the two aforementioned passage sites.
Results T h e woodcock, stone curlew and lapwing, and the spring migration of the snipe have been omitted from the analysis because of incomplete recording.
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Species Snipe Green sandpiper Common sandpiper Little ringed plover Ringed plover Greenshank Dunlin Ruff Redshank Wood sandpiper Little stint Other species (nine of waders and three of terns) Total
Aggregate (of 8 seasons) 1,319 987 941 227 188 143 128 118 106 74 65
Percentage of Total 30-11 22-53 21-48 5-18 4-29 3-27 2-92 2-69 2-42 1-69 1-48
85
1-94
4,381
100
Excluding four species, viz., woodcock, stone curlew, lapwing and golden plover, the table shows eleven species representing individually over 1% and collectively over 98% of the autumn total of waders and terns. Oystercatcher: 1950-75: only four occurrences (viz., two in March, one in September and one in October) totalling six individuals. R i n g e d plover: spring passage (1950-75) was recorded from February 28th to June 13th. There were small peaks in March (second half) and May (second half). Nisbet (1957) considered the March peak to represent the arrival of the British breeding population, migrants in April and May being destined for breeding quarters in Scandinavia and the arctic. Autumn passage (eight seasons): August provided 61% of the autumn records, there being a peak in the second half of that month, a decrease from mid-September, and none recorded after September. Little ringed plover: formerly rare (Payn, 1962), this species is now regulär in autumn at passage sites in West Suffolk. The increase in passage records dates from the late sixties and coincides with the rapid increase, especially evident since 1968, in the British breeding population (Parrinder and Parrinder, 1975). Spring records are largely of birds arriving at breeding sites. Autumn (eight seasons): August provided 59% of the autumn records, there was a peak in the first half of that month, and none was observed after October 13th.
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Grey plover: 1950-75: only one record: one in October, 1972. Golden plover: spring passage (1950-75) was recorded up to April 28th, and included flocks of birds of the northern race altifrons. There was a peak at the end of March, including large flocks of 1,300 on 31.3.63 and 1,500 on 24.3.68, both at Livermere. Autumn passage (eight seasons) began in late July and there were two small peaks, viz., one at the end of August/ early September, and another at the end of September/midOctober. Dotterel: 1950-75: only one record: one in May, 1957. Turnstone: 1950-75: seven occurrences, totalling individuals: two in April/May and six in July/September.
eight
Snipe: spring: see ante. Autumn (eight seasons): a gradual increase over the autumn period, with largest counts in October. The period June 16th/July 31 st accounted for only 3% of the autumn total. Jack snipe: 1950-75: probably under-recorded: a sprinkling of records up to April 30th and from August Ist, with no recognisable peaks. Curlew: 1950-75: most spring records are of birds arriving at breeding sites in the Brecks. Observations at purely passage sites were more numerous in autumn than in spring, and parties of up to twelve birds occurred from mid-July to September, with most in August/September. Whimbrel: 1950-75: spring: five occurrences totalling seven individuals, all in May. Autumn: two occurrences totalling twelve individuals, viz., one in July, 1950, and a party of eleven Aying south at West Row in August, 1963. Black-tailed godwit: 1950-75: despite the existence since 1952 of a small breeding colony at the Ouse Washes in Cambs/ Norfolk (Cottier and Lea, 1969), there have been few observations of the species in West Suffolk, viz., three occurrences of single birds in April/May and six occurrences of six or more individuals during July/August. Bar-tailed godwit: 1950-75: three occurrences during April 28th/May 4th, including a flock of 120 Aying E.N.E. at Risby on April 29th, 1962, and a party of fifteen at West Stow gravel pit on April 28th, 1974. Green sandpiper: spring passage (1950-75) was recorded up to April 29th, with records evenly divided between March and April. Autumn (eight seasons): August provided 56% of the
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autumn total and the species was equally numerous in both halves of the montb. Wood sandpiper: in spring (1950-75) there were only two observations, both of single birds and both in May. Autumn passage (eight seasons) ran from August Ist to September 14th and there was a peak in the first half of August, especially during the period 8th/l Ith. C o m m o n sandpiper: spring passage (1950-75) extended from April 17th to June 2nd, with a peak in the second half of May. Autumn (eight seasons): August provided 61% of the autumn total. There was a peak in the second half of August, and especially during the period 20th/27th which accounted for 26% of the autumn total. Very few were recorded before midJuly or after September. Redshank: one of the most plentiful waders in spring (195075), with a peak in the second half of March. In autumn (eight seasons) a very early peak in late June and very few after midAugust: cf. the Statement by Payn (1962) that adults and young linger in small flocks until late September at such spots as the Bury B.F. Ponds. Nisbet (1957) noted similar peaks at Cambridge Sewage Farm and commented that the relatively early spring migration and the very early autumn migration suggest that the majority of the birds belong to the British race britannica and that there is no large migration of the Icelandic robusta or Continental totanus races which would be expected to pass through later. Support for Nisbet's Observation comes from recent wader studies on the Wash based on ringing, which have shown that the Icelandic redshank starts to arrive on the Wash in early August, staying to moult and winter, while Continental redshanks pass through in August and September (Minton, 1969). Spotted redshank: 1950-75: spring: only two occurrences of single birds in March and May. Autumn passage was noted from June 22nd to September 27th, involving thirteen occurrences and twenty-one individuals. All occurred during August-September except for two in late June, 1970, and there was no recognisable peak. Payn (1962) stated that the species appeared to be rare away from the vicinity of the coast but suggested that regulär watching at suitable inland areas might prove it to be not infrequent inland on passage. While it is true that there have been more records in the past decade as the result of more Observation, the species seems to be of irregulär occurrence, none being recorded in the years 1967, 1968 and 1971, which were all years of intensive Observation at the West Suffolk passage sites.
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Greenshank: spring passage (1950-75) was probably underrecorded, with only six occurrences involving seven individuals, from April 18th to May 24th. Autumn passage (eight seasons) ran from July 18th to October lOth. The period August 16th/ September 15th accounted for 73% of the autumn total, August 24th/27th being the peak 4-day period. There were very few in July and October. Knot: 1950-75: only two occurrences, both at the Bury B.F. Ponds, viz., one in September, 1967 and two in November, 1970. Little stint: 1950-75: no spring records. Autumn passage (1950-75) was observed in only five years and spanned the period August 9th/October 25th. DĂźring the eight seasons, the species was recorded only in 1967 and 1970, with a peak in the second half of September. Dunlin: spring passage (1950-75) extended from February 28th to May 21st, all records being of one or two birds except for a flock of twenty-eight noted at Livermere in late March, 1969. Autumn passage (eight seasons) showed a peak (39%) in the second half of Septembe,-, indicating that the majority of the autumn migrants are of the northern race alpina: vide Minton (1969). Curlew s-" lpiper: 1950-75: recorded in four years, viz., four occurrences totalling 13 individuals; records confined to autumn and to the period August 17th/September 25th. In 1969, when exceptionally high numbers occurred on autumn passage from July 16th to the end of September on the coast, the only Observation in West Suffolk was of four at the Bury B.F. Ponds in September. Sanderling: 1950-75: only two occurrences, both at Bury B.F. Ponds, viz., one in May, 1950 and two in August, 1954. Ruff: in spring (1950-75), a handful of records from April 23rd to May 24th. Autumn passage (eight seasons) reached a peak during the period August 24th/September 4th, which accounted for 58% of the autumn total. Avocet: 1950-75: four occurrences totalling seven birds constitute the only records for inland Suffolk during the present Century (Payn, 1962). Spring: two in late April, 1969. Autumn: three records involving five individuals, between August lOth and September 4th. Grey phalarope: 1950-75: one record, only the second for the present Century for inland Suffolk (Payn, 1962), viz., one seen at the Bury B.F. Ponds during the evening of August 19th, 1970, mmediately after southerly gales, had departed by the following morning.
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Black tern: 1950-75: spring passage extended from April 23rd to June 12th. Spring observations accounted for 89% of all passage records (i.e., both spring and autumn), with 51% in May and 35% in June. Autumn passage was observed from August 5th to September 29th, with 7% of all passage records in August and 4% in September. Common/Arctic tern: 1950-75: spring passage was recorded from April 23rd into June, with a peak in May. Autumn passage ran from July to September 24th, consisting of a handful of occurrences with no clear peak. Little tern: 1950-75: four occurrences involving five birds: in April, May, June and September, including two birds grounded by a thunderstorm at Livermere on June 25th, 1967. Sandwich tern: 1950-75: three occurrences of single birds in May, July and September. Conclusions and discussion Despite the smallness of the sample in some cases, the timing of peak movements of waders and terns in West Suffolk accorded fairly closely with those reported from other inland regions of England (e.g., Hollom (1938), Nisbet (1957) and Mason (1969)). The scarcity in West Suffolk of oystercatcher, grey plover, turnstone, whimbrel, the two godwits, knot, sanderling and the terns, reflects the absence of a major passage site such as a reservoir or sewage farm. Spring passage was on a considerably srnaller scale than autumn passage, with the notable exceptions of black tern, redshank and bar-tailed godwit. Autumn passage exceeded that of spring both in volume and extent. Several of the waders, including ringed plover, little ringed plover, green sandpiper, wood sandpiper and common sandpiper, showed August peaks. Greenshanks and ruffs were most numerous from mid-August to mid-September. Dunlin and little stint each showed a peak in the second half of September. The existence of only one recognisable peak in the autumn passage of the dunlin in West Suffolk, as opposed to the trimodal peak noted in other inland regions, may merely reflect the lightness of the passage in West Suffolk. The intensive observations of the last decade have been responsible for the only records during 1950-75 of grey plover, knot and grey phalarope, and have resulted in increased recording of turnstone, wood sandpiper, spotted redshank, little stint and
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curlcw sandpiper, as well as of the commoner species. However, for other of the scarcer inland migrants, notably oystercatcher, whimbrel, bar-tailed godwit and sanderling, there has been no corresponding increase in records, probably owing to the absence of a major passage site. Acknowledgements I am grateful to C. A. E. Kirtland and R. H. May for the use of their records. References Cottier, E. J. and Lea, D . (1969). Black-tailed Godwits, Ruffs and Black T e r n s breeding in the Ouse Washes. Brit. Birds, 62, 259. Hollom, P. A. D . (1938). Summaries of inland occurrences of some waterfowl and waders 1924-1936. Brit. Birds 32, 34 and 64. Mason, C. F. (1969). Waders and terns in Leicestershire and an index of relative abundance. Brit. Birds 62, 523. Minton, C. D. T . (1969). Wader studies on the Wash. Norfolk Bird and Mammal Report 22, 15. Nisbet, I. C. T . (1957). Wader migration at Cambridge Sewage Farm. Bird Study 4, 131. Parrinder, E. R. and Parrinder, E. D. (1975). Little Ringed Plovers in Britain in 1968-73. Brit. Birds 68, 359. Payn, W . H . (1962). T h e Birds of Suffolk. Barrie and Rockliff (Barrie Books Ltd.) London. T h e Suffolk Bird Reports, 1950-74.
A. J. Last, 130 Fornham Road, Bury St. Edmunds,
Suffolk.