INTRODUCTION. xv 



studied the behaviour of the young birds, uninfluenced by 

 all education and example. In his clear-cut experiments he 

 showed, for instance, that the newly hatched chick has a 

 very open mind, with few intuitive perceptions — not even 

 of water as suitable for drinking, nor of the meaning of its 

 unseen mother's cluck, and very few instinctive prejudices, 

 for it gorged itself with ' worms "* of red worsted. Without 

 doubt, this line of investigation requires to be followed 

 farther ; it is sure to lead to interesting results. More- 

 over, it is a pleasant path to pursue. 



Particular Problems : Migration. 



Another form of bird - study is that which concen- 

 trates attention on one particular problem of behaviour, 

 such as migration. Every one who has looked into the 

 matter at all must have discovered that certainties in 

 regard to the migration of birds are few. Some broad 

 facts are well established ; but how little is known of the 

 paths followed, of the order observed, of the velocity and 

 altitude, of the return to old quarters. To what extent 

 is migratory activity instinctive — what immediate stimuli 

 prompt the autumn emigration from our shores and the 

 return in spring ? How did the habit begin ? How is the 

 way-finding to be regarded ? It is a good rule in scientific 

 inquiry to attack the more commonplace questions first ; 

 to ask, for instance, not How do the birds find their way ? 

 but What way do they find ? Much has been done by 

 careful observation and recording ; much has been done by 

 the systematic searching of a small area (as Gatke did in 

 Heligoland) ; much has been done, notably by Mr Eagle 

 Clarke, in utilising the remarkable data accumulated on 

 lighthouses ; much is being discovered by the ' ringing ' 

 method, most successfully followed for the last seven years 



