Page:The British Warblers A History with Problems of Their Lives - 2 of 9.djvu/43

 her brood in the morning as soon as there is sufficient light, about a quarter to four, that is to say, an hour or so after dawn. Her routine of feeding alters day by day, according to the growth of her offspring. For the first day or so she will bring one supply of food, then remain on the nest brooding her young for a period of about twelve minutes, then again go in search of the one supply, and so on. During the next stage, when the young are a few days old, she will bring food twice or perhaps three times, then remain on the nest for the same period as before; thus the food supply increases day by day until it becomes almost continuous. I have carefully noted the actual time spent in brooding her offspring, and have found this period of twelve minutes adhered to with remarkable accuracy, varying only a minute one way or the other. The fæces is carried away, but not each time that food is brought, and deposited some distance from the nest, or else eaten.

She frequently uses her call-note when approaching the nest, but this may be due to my presence. When on the nest brooding her young she sings quickly and quietly to herself—this often just before she leaves the nest—and it sounds very much like a quiet purring note, which can be heard only a few feet away.

Her nervousness at any human presence varies very considerably. If you take up a position near the nest at dawn before she leaves it, she will not be so nervous; if, on the other hand, you are later and arrive while food is being brought, she will sometimes be more nervous, resenting your presence; and again, after you have been there some considerable time, she will suddenly be seized with a nervous fit, which takes her some time to overcome; thus she will work backwards and forwards up to the nest, approaching even to within a few inches, and as rapidly retreating, but unable apparently to summon up courage to make the final effort to reach it.

It is interesting to notice the manner in which the nest