Page:The British Warblers A History with Problems of Their Lives - 8 of 9.djvu/33

 ; we observe an active response on one occasion and are surprised to find an absence of response on another; there is no uniformity of behaviour in this respect. When the motor reactions are excessive and much suffused with feeling tone, we rarely find occasions when the usual stimulus will not produce the customary active response, but when the emotional behaviour as a whole does not occupy so high a level of development such occasions are by no means uncommon, and it is therefore not always easy to decide as to the extent of the variation between one individual and another.

The young are hatched in about twelve days and remain in the nest from nine to ten days. They are naked at birth and have their eyelids sealed. The colour of the inside of the mouth is pink, and two dark-coloured spots are conspicuous at the base of the tongue. On the third day their eyes are open and the primaries are then just appearing, and on the fourth day the feathers on the back appear, the primaries being ¼" in length. Between the fourth and fifth days considerable advance is made in their growth and the quills can be seen on all the feather tracts. On the sixth day feathers appear on the breast and flanks, and between the sixth and seventh days another considerable change is noticeable, as all the feathers begin to show colour. During the remaining two days or so growth continues rapidly, but nevertheless they finally leave the nest in what seems to be a very undeveloped state considering the dangers that threaten them. The thick tangled undergrowth, in which they so successfully conceal themselves, secures them no doubt from certain enemies, though at the same time increasing the risk from others. The smaller rodents which abound in such places must make havoc amongst such helpless victims. At this stage the young sit singly or together on the smaller branches of some thick bush and utter periodically a faint note which is difficult enough to hear but still more difficult to locate. This note acts as a guide to the