(825) Cisticola juncidis cursitans (Frank.).
THE COMMON STREAKED FANTAIL-WARBLER.
Cisticola juncidis cursitans, Fauna B. I., Birds, 2nd ed. vol. ii, p. 422.
This little Fantail-Warbler has an immense range, being found over practically the whole of India, Burma, Siam and Yunnan from the plains up to at least 6,000 feet, at which height it was very common in the Khasia Hills. It is a bird of grass-lands and open cultivated country where there is plenty of grass to breed in. Even in Sind the bird is common wherever it can find suitable cover, and Ticehurst gives a curious instance of the way it finds out new ground. He writes (Ibis, 1922, p. 552) :—“On the East side of Karachi there is a depression out in the desert, which after rain fills up and quickly becomes full of rushes and sedges ; this spot in mid-August, 1919, was bare desert (and had been so nearly two years) ; it filled on 26th August, and, as soon as enough cover grew up, several pairs of Cisticolas turned up and bred ; now the nearest habitat of these birds was a good three miles away, and to reach their new ground must have crossed a considerable (for them) stretch of unsuitable country.”
Wherever found, the birds seem to swarm in almost incredible numbers. In parts of Assam I could easily have found twenty or thirty nests any day I chose, at the height of the breeding season, and Herbert says that at this time in Siam he, too, has seen as many as thirty nests in a morning.
Their favourite haunts in Assam are the wide stretches of sun-grass between 1,500 and 6,000 feet, which sometimes run over the undulating hills for miles without a break. In other places pockets and ravines full of evergreen forest break them up into smaller areas. In many places stunted Oaks are scattered here and there among the grass, especially where is is shortest, not over 3 feet in height. Here the little birds build their nests in the grass- tufts or, less often, in among weeds of various species. The nests are of two kinds. Perhaps the most common is shaped like a tiny narrow bag or purse, not more than a couple of inches across by anything in depth from 3 to 5 inches. This is always attached to several stems of grass, these being incorporated in the materials along the sides for some distance as a rule but, in a few, only joined to the nest for an inch or so at the top. The materials consist only of fine grass-stems, often with the flowering ends still on, whilst the lining is of the soft flowering ends alone. The second type of nest is shaped like an egg, the small end uppermost, and with a large entrance near the top. These nests, which measure roughly 1.1/2 inch across by about 3 inches deep, are fastened sometimes to the stems, sometimes to the blades of grasses, in the latter case the blades often being worked in to form part of the nest-walls. In these oval nests the materials for the body and hning are the same as in the other type of nest. They are placed low down, seldom as much as 3 feet from the ground, and often within 6 inches of it. They look flimsy affairs but are much stronger than they look, the clever way in which the grass-stems are interlaced to the nest giving it quite strong support.
In all nests, I should note, a few cobwebs are used and, in some, a great many ; these seem to be mixed with the soft seed-fluff from the grass-ends and worked with them into the nest. In some nests also I have found a silky material which I cannot identify, but which may be from the cocoon of one of the silk-moths. The lining is often so worked up that it appears almost like soft white felt.
This Warbler and the birds of the Suya group suffer more from Cuckoos than any other birds I know of. How the Cuckoo gets the egg into the nest is a mystery, and certainly it seems that by no other way than with its bill could the deed be accomplished. Certainly the Cuckoo could not-get into the nest, for the young Cuckoo, when half grown, looks as if enclosed in a grass net and, finally, this bursts and drops the young Cuckoo to the ground.
Outside Assam the egg-shaped nest seems rare, but Hume found such occasionally and says that Brooks obtained a similar one. In Assam about one in three is of this oval type.
The breeding season depends on the rains, and in most parts of India the great majority of birds do not breed until after the rains break. Round about Deesa Butler found them nesting during July and August, and Davidson and Wenden say that “it breeds in the rainy season.” In Eastern Bengal few birds lay until after the middle of June, though Cripps got eggs in May in Faridpore. In Burma they breed when the rains break in June and continue to the end of August. In Assam, where there is so much rain over so long a period, I have known their eggs to be taken from March to September, and there many birds have two and some have three broods. In Siam Herbert says :— “If the rains are good the nesting season is from early May to the end of August” ; but he also says “a spell of dry weather will check the nesting, only to be continued with renewed vigour as soon as the rains set in again.
As regards the number of eggs laid, Hume says that in most parts of India five is the usual complement and, at Deesa, Butler took several fives. In Assam four forms the normal clutch, five fairly often, and six only occasionally, but in Lower Burma Mackenzie took several clutches of this number.
The great majority of eggs have a china-white ground and are freely speckled and spotted all over with pale red, dark red-brown, or purple-brown, without any secondary spots, though a few may be paler than the others.
In some eggs the specks become blotches and, in about one clutch in twenty, or less, they become large blotches. Normally, though more numerous at the large than the small ends, they do not form rings or caps ; every now and then, however, one comes across such, and I have one clutch of eggs with dense rings of tiny deep red-brown specks and another with well-defined broader zones of pinkish-red, enlarged to a cap in one egg. One clutch of three is a very glossy white with a few round spots of pale chestnut.
About one clutch in twenty has a very pale blue ground and, more rare still, is a type with a pale pink ground ; these varieties may have any of the modifications in marking already noted.
I have one clutch a pale unspotted blue.
In shape the eggs are usually broad, blunt ovals and in this they are very constant. The shell is close, fine and hard, generally with quite a pronounced gloss.
Four hundred eggs average 15.0 x 11.5 mm. : maxima 16.8 x 10.9 and 16.0 x 12.3 mm. ; minima 13.3 x 11.2 and 13.4 x 10.2 mm.
Both sexes take part in the construction of the nest and both incubate but, here again, the female does more than the male.
The time taken to build the nest varies greatly. I have seen one completed in four days and an egg laid on the fifth ; yet another nest took fourteen days to build, and the egg was not laid until the sixteenth day. I think most nests take about a week to build, the birds working hardest in the mornings and evenings.
Incubation takes only ten days, as I have twice ascertained, though this seems very short a period.
825. Cisticola juncidis cursitans
(825) Cisticola juncidis cursitans (Frank.).