The Zoologist/4th series, vol 1 (1897)/Issue 667/On the Occurrence of Pallas's Willow Warbler in Norfolk

by Thomas Southwell

 

ON THE OCCURRENCE OF PALLAS'S WILLOW
WARBLER IN NORFOLK.

By Thomas Southwell.

 

In the December number of 'The Zoologist' I had the pleasure briefly to record the occurrence of a specimen of the above rare Warbler, Phylloscopus proregulus (Pall.), at Cley-next-the-Sea, Norfolk, on Oct. 31st last.⁠Mr. Ramm, the person who shot the bird, tells me that he found it amongst the long grass on the bank or sea-wall, not far from the sea, at Cley, a locality which has produced many rare migrants, and at first took it for a Goldcrest, but on approaching to within two or three yards, the bird being very tame, he thought he recognized a Yellow-browed Warbler, a species he had seen before, and therefore secured it. Mr. Pashley, of Cley, to whom the bird was sent for preservation, forwarded it to me for determination, as he had some doubt whether it was really a Yellow-browed Warbler; and, with the assistance of Mr. Gurney, we were able to identify it as Pallas's Willow Warbler, Phylloscopus proregulus. This Mr. Dresser was good enough to confirm; he also exhibited the specimen, which proved on dissection to be a female, probably adult, at the meeting of the Zoological Society on Dec. 1st, 1896.

Considerable confusion exists in the writings of the ornithologists of the first half of the present century with regard to two nearly allied species of this difficult group. I should therefore be glad if you will allow me to make a few remarks, which I hope may assist in placing in a clearer light the history of the claims of this, and the Yellow-browed Warbler, to be regarded as accidental migrants to the eastern shore of Great Britain.

Phylloscopus proregulus seems to have been first described by Pallas in the 'Zoographia Rosso-Asiatica,' which appeared in 1811, but was probably little known (if at all) to British ornithologists till the publication of Gould's 'Birds of Europe' in 1837 (vol. ii. p. 149), where Mr. Gould describes a bird, then new to him, and as he also believed new to science, which he named Regulus modestus, with the trivial name of "Dalmatian Regulus," commemorative of the locality of its origin. Mr. Gould's words are as follows:—"A single specimen of this interesting little bird has been sent to us by the Baron de Feldegg, of Frankfort, to whom our acknowledgments are due .... for this instance of his liberality in consigning to our care .... a bird probably unique in the collections of Europe." The only history of the bird which Mr. Gould was able to obtain was that written on the label attached to it by De Feldegg, as follows:—"I shot this bird, which on dissection proved to be a male, in Dalmatia in the year 1829"! Mr. Gould further adds that he named the species modestus in allusion to its chaste plumage, as he could not find that it was known to German ornithologists.

The next we hear of the "Dalmatian Regulus" is in a communication to the 'Annals of Natural History' (vol. ii., Dec, 1838, p. 310), in which the late John Hancock, of Newcastle-on-Tyne, states that on Sept. 26th, 1838, he shot, on the banks near Hartley, on the coast of Northumberland, a bird which "corresponds exactly with Gould's Regulus modestus," and claims the species as British. His observations on the manners and appearance of the bird, which are as follows, are interesting:—"Its manners, as far as I had an opportunity of observing them, were so like those of the Golden-crested Wren that at first I mistook it for that species. It was continually in motion, flitting from place to place in search of insects on umbelliferous plants, and such other herbage as the bleak banks of the Northumberland coast affords. Such a situation could not be at all suited to the habits of this species, and there can be little doubt that it had arrived at the coast previous to or immediately after its autumnal migrations." Thus the "Dalmatian Warbler" came to be regarded prematurely, as will be seen, in the light of a straggler to our shore, and was for a time duly accepted as such.

"Meanwhile," to quote Prof. Newton in Yarrell's 'British Birds' (vol. i. p. 443), "it was shown in 1840, by Count Keyserling and Prof. Blasius (Wirbelth. Eur. p. lv), that Mr. Gould's Regulus modestus was no new species at all, but one described many years before by Pallas," as above mentioned; this, however, of course did not remove the species from the European avifauna, but only cancelled Mr. Gould's name in favour of that conferred by Pallas at an earlier date. As will be seen, however, it had to disappear for a time from the British list, as it was further discovered that Mr. Hancock's bird had been wrongly determined, and belonged to a closely allied species, the Motacilia superciliosa of Gmelin, the Yellow-browed Warbler. Mr. Swinhoe pointed out the distinctive features of the two birds in the 'Proceedings' of the Zoological Society for I860 ("Catalogue of the Birds of China"), p. 297, and further stated that Mr. Hancock's specimen was specifically identical with examples of the Yellow-browed Warbler obtained in China. Thus we lost the Dalmatian Warbler as a British bird, and obtained the Yellow-browed Warbler in its place.

In the 'Ibis' (1867, p. 252) Mr. Hancock corrects his previous determination of the bird killed by him in 1838, stating in what respects he found it to differ from Gould's Regulus modestus; and Mr. Gould does the same in the second volume of his 'Birds of Great Britain' (1873), when referring to the confusion which had arisen in consequence of Mr. Hancock's bird having been regarded by many authors as specifically identical with that received from Baron Feldegg, and figured by him in the 'Birds of Europe' under the impression that it was a newly discovered species. It may be mentioned here that Phylloscopus superciliosus has subsequently been met with in Britain in some eleven instances, one of which was on our own coast at Cley on Oct. 1st, 1894. Having thus disposed of this puzzling subject, we may turn to the bird under immediate consideration.

The next and only other occurrence of Pallas's Willow Warbler (Dalmatian Warbler) in Europe, until the Norfolk specimen, so far as I know, is that mentioned by Herr Gätke in his 'Birds of Heligoland' (p. 293). On Oct. 6th, 1845, Claus Aeuckens, one of his most devoted collectors, then a youth, and not having arrived at the age when he might be trusted with powder and shot, armed only with "a hunting-bag full of rounded pebbles, which he knew how to employ with the most astonishing dexterity," killed a small Warbler with one of his stones "as it was flying round the face of the cliff, and completely crushed it against the rock." Aeuckens noticed that the bird was an unusual one, and brought a wing which had remained undamaged, "with a portion of the lower part of the back with part of the lemon-yellow plumage still adhering to it," to Mr. Gätke, who at first inclined to the idea that it belonged to a species of Regulus, but Aeuckens emphatically insisted that the bird was a Warbler. It was not till the year 1879, when Von Homeyer visited him, bringing a Siberian skin of P. proregulus, that he fully satisfied himself his wing belonged to a bird of that species. On Oct. 29th, 1875, Aeuckens, accompanied by his nephew, again saw a bird of this species a few steps in front of him, under the edge of the cliff, in such a position that had he shot it, it would have fallen into the surf below; they had ample leisure to contemplate the bright lemon-yellow plumage of the lower part of its back, but no opportunity offered of securing it. Finally, by the occurrence of the specimen at Cley on Oct. 31st last, after various changes and much confusion, we are able to restore Mr. Gould's so-called Dalmatian Warbler—really Pallas's Willow Warbler—to a place in the list of accidental visitors to Britain; and it may be that, attention having been called to the distinguishing characters of the species, it will be found, as in some other instances, to be of more frequent occurrence than has hitherto been suspected.

The distribution of this species is thus given by Mr. Seebohm in the 'Catalogue of the Birds in the British Museum' (vol. v. p. 72):—"Pallas's Barred Willow Warbler breeds in the subalpine districts of South-eastern Siberia, and throughout the alpine districts of the Himalayas from Cashmere to Burma, passes through North China on migration, and winters in South China, Burma, and Bengal"; and, it may be added, occasionally straying as far westward as Heligoland and the east coast of Britain. Mr. Dresser, in part ii. of the Supplement of his 'Birds of Europe' (March, 1895), gives some very interesting particulars with regard to the distribution and breeding habits of this species, in which, however, he exercises considerable discretion, as it has so often been confounded with Phylloscopus superciliosus: "In its habits, mode of life, and nidification, although it cannot well be separated generically from the Phylloscopi, it shows affinity to the genus Regulus, whereas P. superciliosus is a true Willow Wren." Mr. Gätke is of opinion that there exists a difference between the Siberian and Indian forms of this bird; but Mr. Dresser, as a result of his examination of specimens of both the northern and southern forms, finds the differences so slight and the individual variations so frequent that he cannot support Mr. Gätke's views. Should such a difference, however, be found to exist, he informs me that the Norfolk-killed bird would certainly belong to the Siberian form.

"It frequents pine-woods, and those of mixed pine and birch in hilly districts, sometimes ranging in the mountains as high as the border of tree-growth, and it is also met with in the beech-covered valleys." The call-note is said by various authorities to be seldom repeated, and to be rendered as tsii, very different from that of P. superciliosus; and the song of the male, which is continued for hours without intermission, is described as melodious, varied, and sweet, and "so loud that it rings through the forest, and is astonishing as coming from so small a bird." The nests are placed on the branches of pines or cedars, either near the outer end or where the junction of the bough with the stem takes place; they are neatly constructed of the materials at hand, such as grass-bents, moss, and lichens, partially domed and lined with feathers and hair. The eggs, which are produced from late in May in the southern localities to the middle of June in Eastern Siberia, are five in number, pure white, richly marked with dark brownish-red and deep purple-grey spots, chiefly at the larger end; and the female is said to "commence sitting directly the first egg is laid, so that in the same clutch one finds quite fresh as well as incubated eggs" (Dresser, 'Birds of Europe,' Supplement, ii. p. 76).

In my previous notice of the occurrence of this bird, in the December number of 'The Zoologist,' p. 467, I remarked that this species may be distinguished from P. superciliosus by "the pale mesial line on the crown." I should have stated that this "mesial line" in P. superciliosus is much paler than in P. proregulus, and that in females and young birds, according to Mr. Gätke, there is not even a trace of it. The most conspicuous difference, however, is the pale yellow colour of the rump in the latter species.