BRITISH WARBLERS
parents, who are then indefatigable in searching for food and keeping them fully supplied.
Whilst the young are actually in the nest, the parents share in the task of securing food and cleaning the nest, and both are suspicious and create considerable commotion if the nest is approached too closely. Their suspicions, however, can be allayed to some extent by patience, but no matter how quiet one is, or how well concealed one appears to be, they never seem quite to overcome their shyness, and consequently their behaviour is strained and they either hesitate at the last moment or divide the food very hurriedly amongst their offspring. Of the two, the male is perhaps the more courageous until his suspicions are thoroughly aroused, when he appears to find greater difficulty than his mate in recovering his natural composure. When the nest is first approached, the bird that is brooding or tending the offspring commences to utter the peculiarly harsh note of the species; its mate then hurriedly approaches the scene, and the combined vocal efforts of the two produce a commotion which is somewhat unusual in the bird life of the neighbourhood. Individuals belonging to other species approach the scene of disturbance, Redbreasts, Whitethroats, Chiff-chaffs, Blackcaps, and even other Garden Warblers quietly draw near and flit amongst the surrounding branches. Some add to the commotion by their own vocal efforts, others are silent, but it is usually a considerable time before quiet is again restored. So long as the intruder remains by the nest the commotion is liable to recur, stimulated by the harsh alarm note of the parents, and in this respect they differ from many species which, when once their alarm has subsided, proceed naturally with their instinctive routine of activities. Even whilst carrying a full supply of food they may utter their alarm note until they approach to within a few yards of the nest, when it is replaced by a purring sound which is replied to by the young. Both parents share in the brooding of the young, and the one leaves the nest in reply to a note uttered by its partner. When the young are
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