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THE MOULTS AND SEQUENCE OF PLUMAGES OF THE BRITISH WADERS. BY ANNIE C. JACKSON, HON. MEM., B.O.TJ.
I. INTBODFCTORY.
THE object of these notes is to give a brief account of the sequence of plumage and moults of the waders on the British List, which at the moment of writing number sixty-four species. I have endeavoured to interpret the facts correctly from the material at my disposal, but in some cases my notes are unfortunately incomplete owing to want of material; while in other cases the examination of larger series of skins may reveal new facts. I wish to express my gratitude to Lord Rothschild and Dr. Hartert for permitting me to utilize the Tring collection, also to the authorities of the Natural History Museum, South Kensington, for kind permission to work there, and to Mr. H. F. Wither by for the loan of his collection and for much valuable help. I should also like to thank Mr. W. Berry, Col. E. W. Home and others who have assisted me in obtaining material I required. Before detailing the result of my investigations, brief references to the literature already published on the moult of the waders will be of interest. The most important papers I am aware of are as follows: " On the Change of Colour in Birds through and irrespective of Moulting," from the Swedish of W. Meves, translated by H. E. Dresser (Zoologist, March, 1879). In this paper birds are divided into four groups according to the number and completeness of their moults. To the first group belong those which have a single and complete moult in autumn, and in this are included the following genera of waders : viz., Scolopax, Numenius and Becurvirostra. The second group deals with birds which have a double or spring moult and is further subdivided into those which in spring have: (a) entire, involving all or most of the body-feathers and sometimes also the two middle tail-feathers and three inner wing-quills as, for instance, Hcematopus, Charadrius, Strepsilas, Tringa, Totanus, Phalaropus, IAmosa among the waders ; (6) partial, involving only some feathers of the head and neck as, for instance, Vanellus cristatus among the waders. The third and fourth groups do not concern us. 56 BRITISH BIRDS. [VOL. xi " Notes on the Birds of Natal and adjoining parts of South Africa," by H. Seebohm, Ibis, 1887, page 338, in which it is stated that the Charadriidce moult their primaries in spring as well as in autumn. This paper will be referred to later. " The Changes of Plumage in the Dunlin and Sanderling," by Frank M. Chapman, Bull. Amer. Mus. Nat. Hist., Vol. VIII., 1896, pp. 1-8. This paper is a criticism of Herr Gatke's remarks in the Birds of Heligoland on colour- change without moult. Mr. Chapman points out that the breeding-plumage of both these species is acquired by a moult and not by a change of colour without moult as implied by Herr Gatke. " On the Annual Molt of the Sanderling." by Witmer Stone, Proc. Acad. Philad., 1897, pp. 368-372. The author of this paper confirms Mr. Chapman's remarks on the moult of the Sanderling, and gives more particulars of the autumn moult of this species. " The Moult of the North American Shore Birds" (Limicolce), by Dr. Jonathan Dwight, Junr., The Auk, 1900, Oct., pp. 368-385. In this comprehensive and important paper, Dr Dwight divides the Limicolm into two " classes " ; in the first he places those in which the young birds retain " the juvenal plumage, modified only by wear, until a mid winter or spring moult takes place " ; in the second he includes those which assume " a distinct first winter plumage by an early post juvenal moult, which involves only the body feathers, the tertiaries and a few of the lesser wing- coverts." In the first class he includes the following species which appear in the British List: Pectoral Sandpiper, Solitary Sandpiper, Spotted Sandpiper, Killdeer, Semi- palmated Plover and Turnstone. Except for the Pectoral Sandpiper, of which I have examined very few juveniles in autumn, I find that all these species assume their first winter plumage by a partial moult, and therefore I cannot agree with Dr. Dwight that they should be placed in his first class. Dr. Dwight then goes on to discuss other questions of moult—I will refer to his conclusions later as occasion arises. Besides the papers already referred to, the Bev. W. Whitear, Yarrell, Mr. N. Severtzoff, *Mr. J. G. Millais (" Notes on the Changes of Plumage of Calidris arenaria," Ibis, 1896, pp. 455- 457), Gatke (" Changes in the Colour of the Plumages of Birds without Moulting," in The Birds of Heligoland), Mr. P. W. Headley (in The Structure and Life of Birds) and others have written expounding the theory of a change of colour without moult and citing the assumption of certain VOL. xi.] MOULTS OF BRITISH WADERS. 57 plumages in some waders as instances. Beyond saying that all the different plumages assumed by the waders are acquired by a moult and do not require the hypothesis of colour change without moult to account for them, I do not intend to enter into a discussion of this vexed theory, which the accumulation of facts I am confident will ultimately entirely disprove. I only wish here to emphasize the fact that colour change without moult, excepting of course effects due to abrasion and fading, plays no part in the sequence of plumages of the Limicoke. I would refer those interested in the literature of this subject to Mr. J. A. Allen's paper on " Alleged Changes of Color in the Feathers of Birds without Molting," Bull. Amer. Nat. Hist., 1896, Vol. VIII., pp. 13-44, which gives a most interesting summary and criticism of the papers written on this subject. Before proceeding to a detailed discussion of each species, it may be well to give the following summary of the moults which I have found to occur in the British waders:— MOULT FROM JUVENILE TO FIRST WINTER PLUMAGE. In apparently all the species of waders in the British List, the first winter plumage is acquired by a post-juvenile moult, but no first winter birds, and few or no juveniles in moult have been examined of the Stone-Curlew, American Pectoral Sandpiper, Buff-breasted Sandpiper, Red-necked Phalarope and Eskimo Curlew. In the Common and Black-winged Pratincoles, this moult involves the remiges, in the Cream- coloured Courser it would appear that in some individuals the remiges and their coverts are also renewed ; in the rest of the waders the remiges are only exceptionally renewed, the moult being confined to the body-feathers, usually some or all of the tail-feathers, some innermost secondaries and coverts, and usually some median and lesser coverts. The moult of the tail-feathers, innermost secondaries and coverts, and median and lesser coverts varies individually in many species. In the following species, however, the tail does not appear to be renewed, viz. Semi-palmated Plover (not many specimens examined), Golden Plover, American Golden Plover, Asiatic Golden Plover, Lapwing (an odd tail-feather is exceptionally renewed), Bartram's Sandpiper, Dunlin, Baird's Sandpiper, Bonaparte's Sandpiper, Purple Sandpiper, Solitary Sandpiper, and Grey Phalarope. In the Purple Sandpiper and Grey Phalarope the innermost secondaries and coverts and median and lesser coverts are also not moulted, while in the Yellowshank the median and lesser coverts do not appear to be renewed.
F 58 BRITISH BIRDS. [VOL. XI. First winter birds usually resemble adults, but are dis tinguished by the retained juvenile wing-eoverts, except in the following species in which the first winter bird is indistinguishable from the adult, viz. Common and Black- winged Pratincole (not distinguishable unless some juvenile wing-eoverts are retained), Killdeer (difficult to distinguish with certainty), Golden Plover, American Golden Plover, Asiatic Golden Plover, Common Sandpiper, Spotted Sand piper, Green Sandpiper, Slender-billed Curlew (difficult to distinguish with certainty), Great Snipe (not distinguishable if all the tail-feathers are moulted), Common Snipe, Jack Snipe and Woodcock. Exceptional Instances of Moult of the Remiges in Winter in First Winter Birds. In the following species the remiges are not normally moulted in winter and occasional examples moulting their remiges must be looked upon as exceptional cases: Ringed Plover, Bonaparte's Sandpiper, Siberian Pectoral Sandpiper. MOTJLT FROM FlEST WINTER TO FlRST SUMMER PLUMAGE. This moult is usually the same as the pre-nuptial moult of the adult, though in some species, e.g. Greater Yellow- shank, Redshank, and Black-tailed Godwit, the moult is less complete, a good many winter body-feathers being retained. In the Stilt, the spring moult of the first winter bird, is more complete than in the adult and involves the tail-feathers, which are not moulted in the adult. No examples in first summer plumage of the following species have been available for examination: Oyster- catcher, Stone-Curlew, Semi-palmated Plover, Knot, Curlew- Sandpiper, American Pectoral Sandpiper, Bonaparte's Sand piper, Buff-breasted Sandpiper, Broad-billed Sandpiper, Red-breasted Snipe, Solitary Sandpiper, Yellowshank, Green- shank, Red-necked Phalarope and Eskimo Curlew. First summer birds are usually only to be distinguished from the adults when the retained juvenile wing-coverts are not too abraded. I have examined very few undoubted first summer specimens of any of the waders. This may to some extent be accounted for by the fact that in most waders, when the edges of the juvenile wing-coverts are completely abraded, the first summer birds are indistinguish able from the adults. In addition to those species in which the first winter and adult winter plumages are indistinguish able, first summer birds of the following species cannot be distinguished from the adult in summer: viz. Killdeer, Bartram's Sandpiper, Siberian Pectoral Sandpiper, Baird's Sandpiper, Terek Sandpiper, and Slender-billed Curlew. VOL. xi,] MOULTS OF BRITISH WADERS. 59 Exceptional Moult of the Bemiges in Spring of First Winter Birds. In the following species I have found instances of exceptional moult of the remiges in spring of first winter birds : Ringed Plover, Sanderling and Marsh-Sandpiper, MOULT FROM FIRST SUMMER TO SECOND WINTER PLUMAGE. The second winter plumage is acquired by a complete moult in autumn or early winter as in the adults, after which, with the exception of the Stilt, all the British waders become like the adults. In the Stilt the adult winter plumage is not acquired till the third year. MOULT FROM ADULT WINTER PLUMAGE TO ADULT SUMMER PLUMAGE. Waders may be divided into three classes according to the extent of the pre-ntiptial moult: Class I., those in which the moult is very partial and confined to some of the body- feathers, an occasional innermost secondary or odd median and lesser wing-coverts. Class II., those in which most or all of the body-feathers are renewed, occasionally, in some usually, the central pair of tail-feathers or all the tail-feathers, the innermost secondaries and coverts, some median and lesser coverts. Class III., those in which the remiges as well as the rectrices and body-feathers are involved. To Class I. belong the Lapwing, Stilt and Woodcock. In Class II. are included the large majority of the waders ; in some the tail-feathers are apparently not moulted, viz. Killdeer, Baird's Sandpiper, Purple Sandpiper, while in the Sociable Plover, Dunlin, Purple Sandpiper, Bonaparte's Sandpiper, Semi-palmated Sandpiper, the Red-necked and Grey Phala- ropes, the median and lesser coverts are not renewed (in the Dunlin the central pair of tail-feathers or an odd tail- feather are very occasionally renewed), while in the Dunlin, Purple Sandpiper, and Bonaparte's Sandpiper the inner most secondaries and coverts are only occasionally moulted. To Class III. belong the Little and Temminck's Stints, and probably also the American Stint, but I have examined very few spring specimens of the latter, and the Common and Spotted Sandpipers. In the Stints, both adults and first winter birds moult the remiges in spring. In the Common and Spotted Sandpipers the first winter bird is indistinguishable from the adult and t is impossible to say whether the spring moult of the remiges is indulged in by young and old alike. In both these species adults in worn summer plumage just commencing body-moult occur in October and exceptionally in December or even January. Examples moulting the remiges occur in every month from €0 BRITISH BIRDS. [VOL. XI. September to May. Those with wings in quill in January and February may be adults completing a late winter wing- moult and beginning to acquire at the same time the breeding plumage, or they may be birds of the previous year. Similarly; birds in April—May, with their outer primaries in quill, may be adults or first winter birds indulging in a spring moult. Dr. Dwight states (Auk, 1900, p. 373) that there is abundant evidence that adults and young both undergo a spring moult in which the body-plumage is renewed, while in many species, in the case of the young birds, he believes the moult to be complete—namely, involving reetriees and remiges, except in some females, while in the adults he does not think the reetriees or remiges are involved. He believes this to be the case in the Spotted Sandpiper, Sanderling, Dunlin, American Golden Plover and Grey Plover, but the only definite instance given is one specimen of a Grey Plover (February 27th, Florida) which had renewed all but the two distal primaries. This is probably an instance of abnormal moult. Mr. Seebohm, in his paper, " Notes on the Birds of Natal and adjoining parts of South Africa," states that the Charadriidce moult their primaries in spring as well as in autumn,and says he found the Bay of Durban in March swarm ing with British species—Curlew, Whimbrel, Greenshank, Grey Plover, Ring Dotterel, Wood Sandpiper, Common Sandpiper, Sanderling—-and that half the birds shot had evidently just finished moulting, judging by the bloom upon their remiges, while the other half consisted of birds in every intermediate stage between a partial and a complete moult, the new quills being rich in colour, the rest faded and worn ; unfortunately no mention is made of the species with remiges in quill. Except in the species mentioned in Class III. I have not found any evidence of a normal spring moult of the remiges, but it must be remarked that, in many waders, spring specimens are not so numerous as could be wished. Exceptional Moult of the Remiges in Spring in the Adult. Occasionally spring specimens occur showing moult of the xemiges in a species which normally does not appear to moult them at this season : I have found such instances in the following species: Common Pratincole, Turnstone, Terek Sandpiper, Grey and Red-necked Phalaropes and Whimbrel. MOULT FROM ADULT SUMMER PLUMAGE TO ADULT WINTER PLUMAGE. This moult, which is complete, involving all the feathers, usually commences in July or August, though in some VOL. xi.l MOULTS OF BRITISH WADERS. 61 individuals not till much later, and while by October many birds have completed the moult and are in full winter plumage, yet others will be found with the moult still far from complete. As a rule the remiges are moulted in autumn with the body-feathers, but in the following species it would appear that the remiges are normally moulted in winter and early spring, viz. Bartram's Sandpiper, American Pectoral Sandpiper, Siberian Pectoral Sandpiper, Baird's Sandpiper, Bonaparte's Sandpiper, while I found specimens of the Wood-Sandpiper, Solitary Sandpiper and the Yellow- shank with remiges in quill from September to February or even March, the February—March specimens with the wing moult more or less complete, the second and the third primaries being in quill. In the American Golden Plover the win^-moult appears to take place in late autumn and at the same time winter body-feathers are often renewed, while of the Asiatic Golden Plover several examples with outer primaries in quill in January and February were examined. Exceptional Instances of Winter Wing-Moult.—I have come across numerous cases of individuals of a species which normally moults the remiges in autumn, with one or more of the outer primaries in quill in winter or early spring. I consider these individuals are birds which for some reason or another have commenced to moult late in the autumn and in the months of January and February are only com pleting the wing-moult. Birds with the outer primaries in quill in March may be completing either a delayed winter wing-moult or an early spring one, which can sometimes be decided by examination. Only those birds with the inner primaries in quill in March, or with primaries in quill in April and May, I have regarded as genuine examples of a spring-moult of the remiges. Instances of winter wing-moult were observed in the following species in the months of January or February, 2nd and 3rd primaries being in quill m the latter month, the rest of the wing new : Ringed Plover, Sanderiing, Curlew-Sandpiper, Semi-palmated Sandpiper, Red- breasted Snipe, Common Redshank, Greenshank, Ashy-rumped Sandpiper, Avocet, Grey Phalarope, Red-necked Phalarope, Whimbrel, etc. Dr. Dwight remarks that he found specimens showing winter moult of the remiges " comparatively few." He gives the following instances; CrymopMlus fulicarius one, February 21st; Tringa fuseicollis one §, January 16th ; Actitis maeularia one $, February 9th ; Charadrius sqtmtarola, February 27th ; he believes these to be young birds. €2 BRITISH BIRDS, [VOL. XI.
IRREGULAR AND ABNORMAL MOULT. I should like briefly to refer here to cases of irregular and abnormal moult. Irregularity in moult concerns (1) the time, i.e. month of the moult; (2) the extent of the moult. Thus, juveniles normally moult in autumn into their first winter plumage, but some winter and spring examples of the following waders examined were still in worn juvenile plumage, viz. Ringed Plover, American Golden Plover, Sociable Plover, Yellow- shank, Greater Yellowshank, etc., while in some adults, as already mentioned, the moult into winter plumage is delayed and may not be completed till late winter or early spring. There are also many instances of irregularity in the extent of the moult; some young birds retain many juvenile feathers normally moulted in their first winter plumage and there is much individual variation in the amount of the first winter plumage acquired, especially noticeable in the moult of the tail-feathers and wing-coverts, while very exceptionally the moult may even involve the remiges. In some adults, e.g. Redshank and Black-tailed Godwit, there is considerable individual variation in the amount of the summer plumage acquired and exceptionally the wing-quills are renewed at the spring moult. I have also examined numerous examples of adults in autumn, that had assumed some fresh winter feathers and yet had apparently stopped moulting, as no growing feathers could be found, e.g. American Golden Plover 9> Toronto 15/9/96, with fresh winter feathers on breast but no growing feathers apparent; J Truro, August 19th, acquired much winter plumage on under-parts, yet no moult apparent; also specimens of the following species : Asiatic Golden Plover, Curlew-Sandpiper, Little Stint, Temminck's Stint, Semi-palmated Sandpiper, etc. The same thing occurs in some juveniles, e.g. a Bonaparte's Sandpiper, North Truro, August 17th, had acquired many first winter feathers, but no moult was apparent; Dusky Redshank, two females, Amur Bay, September 27th and October 20th, with some winter feathers on mantle, but not in moult. In some adults the moult into breeding plumage seems to stop and then begin again, e.g. Little Stint $, Petehora, July 24th, getting a few summer feathers on head and neck, the rest of the summer plumage worn ; Broad-billed Sandpiper
* Since writing the above, I have read Prof. Patten's article on the " Migratory Movements of Certain Shore Birds as Observed on the Dublin Coast " in the Naturalist (1909, page 83), in the course of which he gives particulars of flocks of Sanderlings, all apparently in nuptial plumage, being seen on the Dublin coast on several occasions during July ; also flocks of Dunlin. He thinks it probable that these are immature birds and that Sanderling and Dunlin do not breed in their first year though assuming a plumage similar to the breeding plumage of the adult; an anatomical examination of some Sanderling, obtained in August, confirmed his views. Prof. Patten also refers to Bar-tailed Godwits in winter plumage being seen throughout the summer on the Irish coast. He concludes that the mature waders migrate straight to their breeding grounds, while those that remain in flocks round our coasts, whether in breeding plumage or not, are immature birds which do not breed in their first year. There is little doubt, 1 think, that such is the case; though the flocks probably contain as well a certain percentage of non-breeding adults.