272 BIRD WATCHING 



" December 2.2.nd. To-day, I saw a number of rooks 

 blackening a heap of straw by a stack, whilst some 

 were on the stack itself. Many were sitting in some 

 elms near about, but they did not appear to me to be 

 acting the part of sentinels. When I tried to get up 

 to the hedge in order to watch the rooks at the stack, 

 through it, they flew off, a good deal later than their 

 friends in the trees must have seen me, and not till I was 

 quite near. If these had really been sentinels, they 

 should have warned the rest, either the instant they 

 saw me, or at any rate, when I was obviously approach- 

 ing, but this they did not do. They were, therefore, 

 either not sentinels or inefficient ones." The second 

 case, however, is more conclusive. 



"January ^>th. To-day, on my way down to the 

 roosting-place, I pass a number of rooks feeding in a 

 field, and not far from the road. They are all more 

 or less together, there are no outposts, though of 

 course there is, of necessity, an outer edge to the flock. 

 But neither on the hedge or in any of the trees near, 

 are there any birds to be seen. On the other side of 

 the field, however, and a very considerable way off, a 

 few are sitting in some trees. It hardly seems possible 

 that these can act the part of sentinels at such a 

 distance, and even if they were much nearer, the feed- 

 ing rooks would have either to be looking at them, to 

 see when they flew, or else, the alarm must be given by 

 a very loud warning note. Bearing this in mind, I 

 alight from my cycle, and walk along the road. The 

 rooks, without any dependence on sentinels far or near, 

 note the fact, bear a wary eye, but continue feeding. 

 I then stop always an alarming measure with birds. 

 The feeding rooks fly off to a safer distance, the ones 



