(512) Oenanthe isabellina (Temm. & Schleg.).
THE ISABELLINE CHAT.
Oenanthe isabellina, Fauna B. I., Birds, 2nd ed. vol. ii, p. 49.
This beautiful Chat is found breeding over a very wide area from South Russia, where it is common in some of the steppes, through Asia Minor, Palestine, Afghanistan, Baluchistan, Persia, Turkestan and Tibet to Eastern Siberia and North-West China.
The Isabelline Chat keeps much to bare rocky hill-sides and sandy, stony deserts but, occasionally, also frequents cultivated tracts which have been abandoned bat upon which there is rather more growth than on the surrounding country. For breeding purposes, however, it seems to keep entirely to broken country, especially stony desert and hill-sides in which there are many ravines with steep rocky sides and boulder-strewn bottoms. The nest is a typical Wheatear’s nest and is as described below by Betham and Williams. The former, in letters to me, describes its breeding well:—“This bird is extremely common round Quettah in Spring and breeds abundantly. It is an early breeder, commencing to nest towards the end of March, and I have found young in the nest as early as the 11th April and another on the 16th April with young nearly fledged. Nests with eggs may be found all through April, and in May and June they have second broods, possibly sometimes a third. The latest I have recorded for eggs is the 2nd June, but second broods may be found up to the end of this month.
“Owing to this Chat’s wariness, its nest is not easy to discover. The bird seems to divine you are after it and its nest and acts accord¬ingly, seldom betraying its home unless there are chicks already hatched. The only nests I found were by watching the birds building, in which case I waited to give them time to lay full clutches, or by seeing them feeding their young.
“The nesting habits are peculiar. Every nest I have found has been placed at the end of a rat-hole, and these always such as have several other passages and channels leading out of it. The burrows selected seemed to be generally winding ones, and the eggs are placed in a chamber rather larger than the tunnel and may be somewhat enlarged or hollowed out by the bird itself, though I am not sure. The tunnels, however, are never made by the bird. The entrance gives no indication of holding a nest and there is never visible any barricade of pebbles.
“The nest itself, which is generally placed one to two feet down the burrow from the mouth, is composed of wool, hair, roots, feathers, cotton, coir, rags, or any other material which is both soft and handy, a conglomerate mass with a depression in the centre, usually rather shallow, in which the eggs are deposited. These are a pale spotless blue and extremely beautiful. Five is apparently the usual complement, although I have taken six occasionally, and more than once four, showing signs of incubation.
“From several nest-holes I have dug out dead half-fledged young birds. It is a common thing also to find toads and dung-beetles occupying the same burrow as that in which a nest is placed, though they are, as a rule, in one of the side passages.
“During the breeding season the male makes himself very con¬spicuous by his courting display. He seats himself on some jutting boulder or bush, puffs out his feathers and “jumps up into the air, uttering a curious guttural note and ascends slowly, with tail out¬spread and all his rump-feathers erected and showing spotlessly white in contrast to their black margins. When he has got up some thirty or forty feet he floats slowly sideways down, finally alighting on some raised ground or the top of a mound, never on the flat ground.”
Later Williams was equally successful in obtaining a series of this bird’s nests and eggs round Quetta. He writes (Journ. Bomb. Nat. Hist. Soc. vol, xxxiii, p. 603, 1929):—“The site chosen for the nest is generally a discarded rat’s or discarded Bee-eater’s hole. When built in the latter it is easy to dig out, but when in a rat’s hole the chances of ever reaching the nest are very remote owing to the numerous diversions in the burrow.
‘‘The nest is a shallow saucer made of wool, grass-stems, tow, feathers and bits of string and rag, lined with hair and wool.
“I have seen the nuptial display of various birds, but that of this bird is, I think, the most remarkable. With drooping wings and outspread tail the male approaches the object of his affections, uttering the whole while a pleasant whistle. When within a foot or so of her he rises about 18 inches off the ground and flutters in a rapid oscillating movement in front of her, only the black and white of his plumage being visible against the drab-coloured earth. After the performance he alights near her and struts round with outspread wings and tail, gaily singing all the time. He then shoots up into the air, hovers and performs aerial stunts, pouring forth his song the while. Gradually his song becomes disjointed and he slowly descends to earth in a spiral motion and, on alighting, slowly approaches his lady love with a hesitating run, both wings adroop and tail still outspread, chirping with satisfaction. All through this wonderful exhibition the female takes not the slightest notice, but carelessly preens her feathers or feeds.”
It should be noted that in 1902 (Journ. Bomb. Nat. Hist. Soc. vol. xiv, p. 603, 1903) Marshall recorded the Chat as very common round Quetta in the hot weather, when he found two or three nests with young about April 20th.
The eggs, as Betham and Williams have said, are laid any time from the 1st of April onwards, second layings being made in late May and early June. The full clutch is nearly always five, though both four and six may rarely be taken. In colour the eggs are a pale blue, varying very little in depth of colour ; in a few there may be half a dozen or so pale red freckles, generally at the larger end, but nine out of ten eggs are unmarked. Most eggs are rather broad ovals and not blunt, but others are decidedly long and decidedly pointed. The texture is of the usual hard, fine character, with a highly developed gloss.
Sixty Baluchistan eggs average 23.7 x 17.4 mm. : maxima 25.0 x 16.6 and 23.0 x 18.0 mm. ; minima 19.8 x 15.1 mm.
Since the ‘Fauna of India’ was written I have received the magnificent series from the Betham collection and others from Williams, and these completely upset my previous measurements and show that Indian eggs, so far from being smaller, average much bigger than those taken from Russia and elsewhere. At the same time it may be that many of these latter have been wrongly identified.
512. Cenanthe isabellina
(512) Oenanthe isabellina (Temm. & Schleg.).