Actitis Hypoleucos) Is Rather Rare As a Breeding S

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COMMON SANDPIPERS ON MIGRATION IN SOUTH GLAMORGAN

BY GEOFFREY C. S. INGRAM. THE Common Sandpiper {Actitis hypoleucos) is rather rare as a breeding species in Glamorgan, even in the northern half of the county, and has only once or twice been recorded as nesting in the southern half. Birds on passage in spring and autumn are numer ous and widely distributed, however, and for the last 23 years— 1922 to 1944 inclusive—I have made fairly regular weekly observa tions on their numbers and behaviour at the Llanishen Reservoirs, near Cardiff. These reservoirs lie inland some two miles from the

Graph illustrating weekly fluctuations in the numbers of Common Sandpipers observed at Llanishen Reservoirs, 1922-1944.

sea, are artificial in construction, faced with stone pitchings all around, and are visited annually by migrating Common Sandpipers, which pause for rest and food on their journeys to and from their breeding grounds further north. The stone pitchings and complete absence of any cover make it easy to obtain an accurate count of the birds present at any visit. Up to the end of September, 1939, Colonel H. Morrey Salmon was regularly associated with me and we are jointly responsible for all observations to that date. 170 BRITISH BIRDS. [VOL. XXXVIII.

PERIOD OF SPRING AND AUTUMN PASSAGE. The above graph has been drawn from material collected over the full period of observation, 23 years, but as many of these years include weeks when absence from home on holidays fell during migration months, a second period of six unbroken years selected from the 23, has been superimposed for the sake of greater accuracy. It will be seen that the difference, except in numbers, is too small to be of any account. Disregarding the records of single birds seen early or late in the year, which can be regarded as excep tional, the spring passage begins in the second week of April and ends during the third week in May, the peak being reached during the last week in April, a period of six weeks. Compared with the autumn passage, beginning in the last week of June and ending in the second week in October, a period of fifteen weeks, it is short and abrupt, the majority of birds arriving and passing within three weeks. The autumn passage, although beginning abruptly, is far less clear-cut, the main movements occupying no less than nine weeks, the peak being reached between the first and second weeks of August. The only exceptionally early date for an individual bird is March gth, 1924, and there are four late dates, November 6th, 1927, November 10th, 1940, December 1st, 1935, and December 16th, IQ34.

NUMBERS. Actually 222 birds including stragglers have been counted in spring and 750 in autumn. These figures may indicate that, birds on passage in autumn are more than three times as numerous than they are in spring, but when the periods of the passages arc compared, six weeks in spring and fifteen weeks in autumn, it seems possible that in autumn a proportion of the birds remain on the reservoirs for two, three or more weeks and are therefore included in more than one of the weekly counts. An examination of the weekly totals rather confirms this supposition, as the following example may show, for it suggests that the six birds present during the first week of July may have remained until the first week of September. July August September

1st 2nd 3rd 4th 1st 2nd yd 4th 1st 2nd yd 4th 6 8 6 6 12 10 6 10 6 o o o In the absence of any definite evidence it is perhaps safer to assume that the birds are, more numerous in autumn, but not to the extent suggested by a comparison of the totals. The greatest number counted on any one visit was 22 in spring, April 26th, 1936, and 20 in autumn, August 12th, 1923. Only on 9.4 per cent, of the visits when birds were seen did their numbers reach double figures. VOL. xxxvni.] SANDPIPERS IN GLAMORGAN. 171

BEHAVIOUR. Autumn birds are noticeably less wild than those seen in spring. Observations confirm The Handbook's statement " generally seen singly or sometimes 2-3 together." The only exceptions to this are April 29th, 1934, a party of six, and another party of six on April 16th, 1935. A compact flock of 18 which moved about together when disturbed was seen on April 26th, 1936. Autumn birds are more often seen singly, and apart from a few records of 3 together, the only other party was one of 4 on September 2nd, 1934. Common Sandpipers have been seen in close company with other species on several occasions, as for instance three with one Green Sandpiper (Tringa ochropus), April 24th, 1932, one in company with an adult male Knot (Calidris c. canutus). May 4th, 1941, and four with an adult Dunlin (Calidris alpina), May 7th, 1944. In autumn there are four records of one or two with Green Sandpipers, and one with a probable Wood-Sandpiper {Tringa glareola), August 13th, 1933.

TOWERING. When disturbed they usually fly off low over the water as described in The Handbook, but on three occasions towering has been observed. On May 13th, 1934, a solitary bird when flushed towered like a Green Sandpiper and flew around overhead calling repeatedly " wit, wit, wit " before flying right away. Again, on September 2nd, 1934, a party of four were seen together. When flushed two made off with characteristic flight low over the water, but the other two towered immediately, rising and circling around at a considera ble height quite silently. On April 18th, 1943, a solitary bird when disturbed towered silently.

DISPLAY. I cannot find any records of birds displaying in spring, when such exhibitions might be expected, but on July 22nd, 1944,1 found three birds together, one of them displaying continuously while the other two fed. One of the three flew off and I watched the remaining two for roughly twenty minutes. During the whole of this period the displaying bird continued to show off or chase the other without a pause. The display consisted of standing bolt upright facing the other bird, with wings held perpendicularly, points of primaries almost touching overhead ; the wings were then revolved with a fanning action, slowly and repeatedly. This pose immediately brought to mind photographs and drawings by W. Rowan I had seen illustrating one of his papers on Alberta waders in British Birds.* I did not hear a note of any kind uttered during this display. The other bird appeared to be unresponsive

•Vol. xx, p. 191, fig. 15, F. c% H. Buff-breasted Sandpiper (Tryngiies suliruficollis.) 172 BRITISH BIRDS. [VOL. XXXVIII. and to resent being followed about at a distance of only 12-15 inches so persistently. It was pressed into flight two or three times, taking off calling '' twee-wee " and closely followed by the displaying bird. Each time they circled low over the water and returned to within a few feet of the spot they had left, when the wing-fanning and chasing was resumed. During the last of these flights the displaying bird broke into a torrent of rapid, trilling notes, quite unlike anything I had heard before from this species, and when it alighted it stood bolt upright without raising its wings and began to utter a penetrating, long-drawn note which it repeated several times, thrusting its head forward at the beginning of the note and jerking it back at the end. After this it resumed its attentions to the other bird, only this time it chased it with alternate quick runs or short fluttering flights, the other endeavouring to avoid it by short, dodging rushes. Eventually both flew off together to the other end of the reservoir and I lost sight of them. The only other hint of autumn display comes to me from Mr. B. W. Tucker, who informs me (in litt.) that at Northampton Sewage Farm on September nth, 1943, he heard two birds " tittering in almost song-like fashion," but saw no definite display.