74 A FIELD GUIDE IN NATURE-STUDY 



Migration. Data such as have been accumulated and recorded in the 

 preceding table will give a concrete idea of local migration phenomena. 

 Migration, however, covers a wide area. Ask each student in the class to 

 write to his friends in North America asking them to inform him when 

 some such familiar bird as the robin first appears in the spring or last 

 appears in autumn. Have all the members of the class get data from 

 friends for the same bird. Have these data reported at class as soon as 

 possible. Thus one student may report that one friend, living in Chat- 

 tanooga, Tennessee, reports robins there all winter; another, living in Nash- 

 ville, Tennessee, reports the first robin seen February 16. Locate Nash- 

 ville on the map on the following page and beside it write the date. Locate 

 Chattanooga on the map and mark it with a red dot; also all the other 

 places from which reports are received and dates when the robin is seen. 

 This should give a graphic representation of the advancing (or in autumn, 

 retreating) wave of migration. 



There follow maps of North and South America. Collect the necessary 

 data and show on the first map, by shading, in what region the bobolink 

 nests; by cross-lines, where it winters; and by a line of arrows, its migra- 

 tion route. On the other maps show the same thing for each of the following 

 birds (names to be dictated by the instructor) : 



