6 



THE ZOOLOGIST. 



it will be seen that the former explanation, apparently the more 

 complex, is in reality the simpler. So that any slight or unusual 

 excitement or irritation -will act on the centres of the brain pre- 

 siding over the motor system through the sense organs without 

 the control or intervention of the higher centres— in other words, 

 without knowledge and understanding, will set in motion actions 

 which habit has associated with particular sensations, and what 

 appears to be robbery and the prevention of robbery resolves 

 itself into automatic though complex movements which in fair- 

 ness may be excused. 



Turning to the way in which the Dunlin finds its food, I wish 

 first to mention the senses of smell and hearing as possible 

 guides. Much has been made of the difficulty of approaching 

 wildfowl down-wind, and the cause has been sought in a keen 

 sense of smell. This may be perfectly true, but it happens that 

 these birds rise up-wind either as a matter of convenience or of 

 necessity, and travel for a time towards the observer who is 

 approaching down-wind. Hence an early start must be made 

 to maintain the margin of safety that each species finds neces- 

 sary. Of hearing, I can say little, and that not much to the 

 point.* 



While it is impossible, without making a difficult and need- 

 lessly cruel experiment, to deny the importance of the senses of 

 smell and hearing, the general evidence places both below two of 

 whose value there can be no doubt — the senses of sight and 

 touch. It is convenient to group them according to their use 

 singly or together, if we remember that there is no hard-and-fast 

 line between each, and that there is scarcely anything to which 

 both cannot be applied. Sight alone is represented by surface- 

 feeding, and by work in places crowded with open burrows in 

 which the occupants are near the surface and within view ; touch 

 alone by the exploration of seaweed, of ground under water, of 

 muddy and sandy ooze, and the sand along the high-water 

 mark; sight and touch by work on areas in which the food 

 supply is scanty and the signs of it indefinite, and in dealing 

 with mud Crustacea which have retreated into the recurved 

 portions of their burrows. 



Surface -feeding includes the search for small objects drifting 



* Cf. Patten, ' Aquatic Birds,' p. 277. 



