Ornithological Observations in Shetland. 91 



as a matter of course, follow their example. Experience, 

 however, has not verified this preconceived opinion, founded 

 on mere plausible ignorance. Even in the case of birds so 

 wary and alert as Woodpigeons or Pheasants, I have found 

 that so potent a cause as my own approach has produced 

 flight or retreat in such individuals (presumably), only, as 

 actually saw me. I say presumably because it is not often 

 possible to be quite certain that when half a dozen or so, for 

 instance, fly off, one or two of these do not merely follow the 

 others. When, however (to take Woodpigeons) the bulk 

 remain, some evidently in a highly nervous state, and anxiously 

 trying to discover the cause of their companions' flight, whilst 

 others sit comparitively undisturbed, and when, during a 

 further stealthy advance, the same class of phenomenon is 

 repeated, the birds going off in successive batches with such 

 sudden action as seems to demonstrate that each individual 

 composing them has caught sight of the intruder, till on coming 

 wholly into view, the residue rise all together or in quick 

 succession — in face of such facts, it becomes fairly evident 

 that each bird of the flock relies directly upon its own sense- 

 impressions of any cause of alarm, and not, except in a subsid- 

 iary degree, upon those of its fellows. This subsidiary degree 

 amounts, as a rule, to no more than a predisposition to flight, 

 owing to the flight, through alarm, of others. It may be 

 greater or less, according to circumstances or individual 

 disposition, but, if not great enough to issue in action, it will 

 gradually subside, in the absence of further ground for appre- 

 hension, so that many a flock that we may come upon, sitting 

 quietly, and, as it would seem, hitherto undisturbed, may be 

 more or less diminished in numbers — unless, indeed, the 

 seceders have returned — through precedent alarms. In the 

 case of Pheasants, I was once much interested in observing 

 that when two birds, having seen me, ran swiftly off, a third 

 that had not seen me, at first followed them but soon stopped, 

 and being still unable to, came back and continued to feed as 

 before. Though I remember this clearly, I can find no record 

 of it, but the following is from notes on the spot : — ' When 

 the small birds fly suddenly off in a cloud, as they do every 

 few minutes with a great whirr of wings, the Pheasants all 

 stop feeding, look about, pause a little, seeming to consider, 

 and then recommence, as though they had decided that such 

 panic was uncalled for and that there was no rational ground 

 of alarm. An hour or two later, three out of the four birds — 

 for two have got gradually to the other side of the stack — see 

 enough of me, in the straw, to make them suspicious, and go 

 off at half pace. The fourth bird notes their retreat, looks 

 all about, can see nothing to account for it, and, instead of 



1917 Mar. 1. 



