Sometimes only about half the flock flies off, the rest not appearing to care much about it; usually a much greater number does, and this often appears to be the whole number, but almost always—unless, of course, on the approach of a man or some other such alarming occurrence—some few, at least, remain. As with the starlings, these flights seem often to be absolutely instantaneous, the birds all rising together in a solid block, but this is not always the case, and the cloud may be preceded by a little half-hopping, half-chasséeing about of three or four individuals, whilst sometimes there is, for a second or two, a very quick following of one another. If this were always so, and if one bird could not fly off without others following it, there would be little or nothing to explain, but, as we have seen, this is very far from being the case. In nine cases out of ten the birds begin to come back almost as soon as they are gone; but, in spite of this, I came to the conclusion that the cause of flight was almost always a nervous apprehension, such as actuates schoolboys when they are doing something of a forbidden nature and half expect to see the master appear at any moment round the corner. Though there might be no discernible ground for apprehension, yet after some three or four minutes it seemed to strike the assembly that it could not be quite safe to remain any longer, and presto! they were gone. Afterwards it was recognised that there had been no real reason for alarm, and they came back, but this seemed to strike them individually rather than collectively. Now it was by stacks in the open fields under no more cover, as a rule, than the neighbouring hedgerow, that I had noticed
