Page:The British Warblers A History with Problems of Their Lives - 2 of 9.djvu/29

 very rapid flight, and chasing him often for some distance beyond the confines of his territory. The interesting part is that the new arrival does not always retaliate, but accepts the situation, as if instinctively conscious that in thus trespassing he was sinning against the unalterable laws of the species.

These territories are sometimes curiously situated. I remember one in which there was a space of about two hundred yards of bare ground between two small coppices, both of which were included by a particular male in his territory; thus he was continually flying backwards and forwards. At one end a sycamore tree (Acer pseudo-platanus) conveniently placed supplied him with food, for numerous Chironomidæ clustered under the leaves, which were somewhat early developed; here he was quite happy hunting and singing for ten minutes or so, then, suddenly darting off, he would rise to a considerable height in the air and make straight for the opposite coppice, returning again shortly in the same manner.

In the early part of the season the difficulty of obtaining food is, no doubt, the dominant factor of his movements; he can then often be seen searching the low holly-bushes, examining the undersides of the leaves very carefully, and a close inspection of these leaves will reveal the Chironomidæ, not in any great, but quite appreciable, numbers. These small flies are evidently the cause of his great activity, but, compared to their numbers a month later, they are few and far between, and for this reason he examines certain trees much more minutely than others, as, for instance, solitary larch (Larix Europæa), the hollies (Ilex aquifolium), some species of willow (Salix) that grow by the waterside, and especially small patches of sprouting hawthorn (Cratægus oxyacantha).

Until the trees are in leaf he roosts in any conveniently warm spot, such as clumps of ivy, thick bramble, &c, retiring to his quarters soon after sunset. When actually roosting he is fearless and not easily disturbed. I have thus