(852) Phylloscopus affinis (Tick.).
THE YELLOW-BELLIED, or TICKELL’S, WILLOW-WARBLER.
Phylloscopus affinis, Fauna B. I., Birds, 2nd ed. vol. ii, p. 454.
This Willow-Warbler is the most common of the many Willow-Warblers breeding within our limits. It is very numerous from the extreme West on the frontiers of Afghanistan and Baluchistan right away to the Eastern Himalayas North of Assam and to South¬-Eastern Tibet.
It breeds at all elevations from about 7,000 feet up to the highest elevations at which sufficiently thick cover of some sort is available for nesting purposes. In Kashmir they breed from 9,000 to 12,000 feet, rarely as low down as 8,000. Whitehead took them in the Kurram Valley at and above 12,000 feet. Crump obtained many nests at Chusal, in Ladak, at 14,000 feet ; in Tibet it is extremely common between 12,000 and 14,000 feet. Whymper took nests in Kuman at about 8,000 to 9,000 feet, whilst in Garhwal he obtained others at 14,000 feet.
A. B. Osmaston (Journ. Bomb. Nat. Hist. Soc. vol. xxxi, p. 990, 1927) remarks: —“This little Warbler is exceedingly common at high elevations, above the tree limit both in Kashmir and Ladak. It is found breeding in the low scrub Caragana and Berberis in Ladakh ; in juniper, dwarf rhododendron, dwarf willow and ber¬beris in Kashmir at from 10,500 to 16,000 feet. No other bird approaching this one in smallness is found at these high altitudes, at any rate in Ladakh, and it is, indeed, strange how such minute birds can survive the low temperature experienced regularly at night and occasionally also during blizzards, by day.
"Nests are of dry grass, domed and copiously lined with feathers, placed in the low thorny scrub from 1' to 2' from the ground.”
A. E. Osmaston (ibid. vol. xxviii, p. 144, 1924) gives much the same description of ground and nest:—“Between the Cher-Hoti Pass and the border of Tibet there lies a valley of gently undulating slopes occupying an area about 6 miles long and 2 miles broad, much of which lies between 12,000' and 14,000' elevation. This valley forms the head-waters of the Girthi River. The climate is Tibetan and the dry, stony and sandy ground supports a scanty vegetation of dwarf loniceras, caragana, juniper and willow. It was in this valley that I found P. affinis breeding in considerable numbers, though I noticed no other members of the Warbler family here. In the first week of August nesting is almost completed and I could only find one nest with half-fledged young, two from which the young had already flown and one deserted nest with eggs. The nests were all placed from 6" to 1' above the ground in low dense willow bushes which were growing in a gregarious manner on a piece of level ground bordering the stream. They were almost round in shape and were constructed of rough grass and lined with feathers.”
As Warblers in the field are not easy birds to identify, the peculi¬arities of each species’ nidification should be borne in mind. This particular bird’s characteristics may be summed up as follows :—
Breeds at high elevations, generally over 10,000 feet, in open treeless country, placing its nest very low down in bushes. Nest globular, rather untidy, made of coarse grass and well lined with feathers.
The hning is generally dense and copious, composed of soft feathers ; sometimes, but not usually, a little fur is mixed with the feathers and both the nests taken by Whitehead in the Kurram Valley had fur in the lining. Macdonald also sent me two nests which had goats’ hair mixed with the feather lining. The nests are not well hidden and several of my correspondents, among them Whitehead, Ward, Crump and Macdonald, all say that the nests are easy to find because they are so often placed in quite conspicuous positions near the outside of the bush.
The breeding season is confined to June and the first half of July, very few birds breeding either earlier or later.
The eggs in a complete set may be four or five, the latter number being obtained in about one nest in four.
The eggs are pure china-white, many immaculate, many faintly and sparsely marked with tiny specks of red at the larger end, where they sometimes form rings, a few only being definitely spotted with rather dark red at the larger end, here and there a speck or two also showing elsewhere. As a rule in each clutch one egg is quite distinctly spotted, one or two faintly spotted, and the others pure white. I have several clutches all pure white but I have no clutch in which all the eggs are well spotted, though I have one four all of which are very faintly freckled at the big end.
In shape the eggs vary from broad to long, pointed ovals. The texture is very fine and close and the surface almost invariably has a fine gloss.
One hundred and forty eggs average 15.5 x 12.0 mm. : maxima 17.2 x 12.3 and 16.0 x 12.5 mm. ; minima 14.3 x 11.3 mm.
Whitehead, in his notes, says that he has caught the male sitting on the eggs, a very interesting fact, and possibly due to the elevation at which these birds breed being so cold that the cock has to incubate when the hen feeds, morning and evening. With most of the Willow-Warblers whose habits are known the cock bird does not sit, but is very careful to drive the hen bird back when he thinks she has stayed away long enough.
852. Phylloscopus afflnis
(852) Phylloscopus affinis (Tick.).