WILLOW WARBLER
the male supplying a great deal of the necessary food. With the growth of the young these conditions alter, and about the sixth day the necessity for a constant supply of food being paramount both parents are consequently indefatigable in searching for and bringing larvæ to their hungry offspring. I cannot recollect having seen a male brooding the young, although he sometimes, for the purpose of cleaning the nest, remains for a few moments in it after having actually delivered up the food he was carrying. The fæces enclosed in a membranous sac are carried away by the parents and eaten or dropped some distance from the nest. For the first two days or so the young develop slowly, but afterwards the growth becomes more rapid. On the fourth day the primaries begin to show and the eyes are partly unsealed. On the sixth day the eyes, are fully open, and by the seventh the young are active and make use of their call note, and the feathers on all the feather tracts show colour. The primaries are about a quarter of an inch long on the eighth day, down being still conspicuous on the head. By the eleventh or twelfth day the birds are sufficiently fledged to be able to leave the nest and fly moderately well, but for a while they remain on, or close to, the ground, being unable to rise to any height or to grasp the branches securely. Their strength, however, soon develops, and they follow their parents, who now roam beyond the boundaries of their territory, until able to find food for themselves. During July and August the males sing less and less, ultimately becoming silent, but after the moult is finished their plaintive song can again be heard occasionally until they leave the country in August or September.
In the life of the Chiff-chaff I remarked upon its peculiarly inquisitive behaviour, and since the Willow Warbler is so closely allied, it may well be asked whether it too possesses a similar trait. I can recall but little evidence pointing to its presence, for although a Willow Warbler sometimes shows excitement for no apparent reason at the presence of a member of another species, yet it is difficult to recognise that constant
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