(362) BREEDING-HABITS OF THE DUNLIN. BY R. H. BROWN. THE Dunlin (Calidris a. schinzii) breeds on the salt marshes fronting the Cumberland side of the Solway Firth and on the fells of the north Pennines. On the salt marshes the breeding ground is the level area of short grass intersected with little creeks and gutters and occasional pools. The breeding ground on the fells is usually above the two thousand feet altitude, where stretches of peaty land, growing cotton grass and broken up into hummocks and deep gutters, with odd little peaty pools, occur amongst the short grass and moss and creeping willow, with outcrops of limestone, that form the vegetation of the fell summits. On the salt marshes the Dunlin usually has for nesting companions the Lapwing (Vanellus vanellus) and Redshank (Tringa t. britannica) and occasionally the Snipe (Capella g. gallinago) and Oystercatcher (Hcematopus o. occidentalis) and Ringed Plover (Charadrius h. hiaticula). On the fells its usual nesting companion is the Golden Plover (Charadrius a. apricarius), and occasionally the Lapwing and Snipe. I have not, so far, found the Dunlin breeding at a greater altitude than 2,700 ft. (young found) and have found both the Golden Plover and the Lapwing breeding at this altitude— young found of both species—whilst I have suspected the Snipe of breeding at this altitude, as I have heard " bleating " in the spring above such high-lying land. On the salt marshes I have found occupied nests of the Dunlin and Redshank thirty-five yards apart; occupied nests of Dunlin and Snipe twenty-two yards apart, and of Dunlin and Lapwing twenty yards apart. In April the Dunlin begins its courtship flight, which is performed by both sexes, whilst frequently three, or even four, birds partake in it and in addition it is often carried out whilst the adults are rearing young. Thus, in twos or threes or fours the Dunlins pursue each other in single file through the air, in a very rapid flight full of sudden twists and sharp turns ; varied with long intervals of gliding when the birds hold their wings half vertically or V-shaped above their backs ; legs straight out; whilst a rich trilling note is uttered that rises in cadence for several seconds, carrying a long way on the still marsh air, then abruptly ceasing. When only two birds, presumably cock and hen, partake in the courtship flight, sometimes only the one bird (the cock ?) utters the VOL. xxxi] BREEDING-HABITS OF DUNLIN. 36$ trilling notes, but on several such occasions both birds of a pair have been heard to utter the trilling notes, indicating that the hen trills as well as the cock. At times a Dunlin will fly almost perpendicularly into the air, and, a certain altitude reached, will hover like a Skylark, gently rising and falling, whilst trilling the lovely rich notes that last for several seconds. Or again, after rising vertically into the air a Dunlin will begin to glide, with wings outstretched and slightly arched, head upturned, legs straight out, and uttering first a series of slow notes that finally merge into the rich trilling notes that rise in cadence for several seconds and then cease. Although it is more usual for the birds to glide with their wings held half-vertically, on several occasions, especially after hovering, they have been observed to glide with wings outstretched and slightly arched, and twice the gliding bird, before trilling, has made a peculiar humming noise that, on a small scale, can be likened to the sound made by the wind through telegraph wires. A somewhat similar humming noise, although on a larger scale, is occasionally made by the Golden Plover during its courtship flight. The trilling notes are sometimes uttered whilst the birds are walking in single file on the mud flats, and parties of obvious non-breeding Dunlins will occasionally burst forth into the trilling notes. There is probably a display on the ground as after perform­ ing the courtship flight a Dunlin, on alighting, will frequently hold one wing aloft, bannerlike, to display the silvery-white underparts. The nest is usually hollowed out in a small tuft of grass, the nest site generally near a pool or small creek. Exceptionally a depression in a grass mound or a peat mound is lined and used, a type of nest site used by the Golden Plover. I have not found a full clutch of eggs earlier than May ioth, but on the other hand day-old nestlings have been found by May 27th one year, and in four different years by May 29th. Mr. Jourdain in Practical Handbook of British Birds, quotes W. Evans's record of the incubation period as twenty-two days; therefore the eggs that had hatched on May 27th must have been laid by May 5th, and those that hatched on May 29th by May 7th. These records refer to the salt marshes but day- old nestlings have been found on the fells, at an altitude of 2,700 ft., by June 1st. The nestlings are an attractive sight on a fine sunny day when crouched on the short turf; their small size, the rich, 364 BRITISH BIRDS. [VOL. XXXI. warm, reddish-buff down shading in places to light fawn and tipped with whitish spots, their little downy bodies make an agreeable contrast with the emerald green of the marsh turf. The nestlings are brooded fairly constantly for the first few days of their lives, usually by the hen, but at times the cock will brood them, and it is during this period that the nestlings are easiest to find. After they are a week old and there is no longer any necessity, especially if the weather is fine and warm, to brood them constantly, the young take to hiding in the gutters and creeks and are very difficult to find, as the adults will not reveal their hiding places, but merely stand, at times preening themselves, and call tSandpiper-fashion, with its back humped, tail fan-spread and trailing, wings VOL. xxxi] BREEDING-HABITS OF DUNLIN. 365 outspread with their tips trailing on the ground, the bird uttering the single alarm note of " twee". On the third occasion the adult, when disturbed from young, flew around in the air, frequently gliding with half-vertical wings and trilling the rich notes of the courtship song. If the first two adults from their behaviour were hens, then possibly the third adult, from its behaviour, was a cock. When both adults of a pair are present it is usual for the brooding adult to fly off the young, but once the young have been found, and especially if the young run a few yards to take fresh hiding, one adult will approach the intruder within a few feet and then begin creeping away from him with humped back and trailing tail and wings, whilst the other adult runs ahead calling, or flies around, hovering at times. It is assumed that it is usually the hen that creeps Sandpiper-fashion along the ground, although, of course, the cock may display like this. Certainly both adults assist at times in brooding the young, as on three separate occasions I have watched both the cock and the hen of a pair brooding the young in turn, and on one occasion I saw a pair changing-over during incubation. One day a solitary adult was flushed from a brood of six young and began creeping along the ground with humped back and trailing wings and tail, at times uttering the alarm note, and in a very short time six or seven adults arrived upon the scene and began running ahead and calling or flying around and gliding or hovering. After an adult had alighted from such a flight it frequently displayed with one wing held aloft, bannerlike, to show the silvery white underparts. On the coast and about the estuaries flocks of non-breeding black-breasted adults may be seen throughout the summer months, but on the salt • marshes where the species breeds, flocking of the breeding adults and young is not usual before the, second or third week in July although exceptionally I noticed flocking in one year by the end of June. On the other hand I have watched breeding adults on the salt marshes in the second week of July which from their behaviour obviously had young in hiding. I have seen black-breasted Dunlins until the second week of October and white-breasted birds, in winter plumage, until the first week of April. Once the breeding season is ended the salt marshes and fells are deserted until the next breeding season and the Dunlins are now to be found about the estuaries and low-lying coast, where they congregate commonly in flocks of hundreds whilst occasionally two or three of these flocks may unite and form 366 BRITISH BIRDS. [VOL. XXXI. one large flock of several thousand birds, and the aerial evolutions of such a large flock on a sunny winter's day, now strung out in one long column, then hanging like a gigantic swarm of bees in the air, are very fascinating to watch. The Dunlin also associates readily with other waders, and parties or small flocks of Dunlins are commonly found during the autumn months feeding in company with Ringed Plovers or Sanderlings or Curlew-Sandpipers about the newly exposed mudflats or where the ebbing tide has left a thin film of water upon a stretch of sand ; whilst in company with Sanderlings the Dunlins frequently feed in the tidal shallows, although the Sanderlings usually wade in deeper than the Dunlins. Ringed Plovers and Sanderlings are also its associates during the winter months, as well as Knots and Redshanks and Godwits.