342 ELEMENTARY ZOOLOGY. 



spending winter and summer, time of migrating, causes, 

 and the effects on the species and its geographic distribu- 

 tion. Is it believed that birds migrate, from year to year, 

 to the exact localities of former years? 



7. Molting in birds. What makes it necessary? The 

 time of its occurrence; different rate of molting; its 

 effects on the bird, etc. The changes of plumage in the 

 ptarmigans. 



8. The diversity in the mating habits of birds. De- 

 scribe the difference in the habits of the males in po- 

 lygamous species and those in monogamous species. 



9. A study of the nests of birds: materials, location, 

 mode of construction, completeness, etc. Relation be- 

 tween the character of the nest and the development of 

 the young at hatching. 



10. The number of eggs laid by different species. The 

 reasons for the difference so far as they can be ascertained. 



1 1 . Compare the vocal powers of birds and the verte- 

 brates hitherto studied. Have their notes any relation 

 to their state of mind? Are the males or females more 

 vocal? Reasons. Where are the " vocal cords" in birds? 



12. Discover the peculiar habits and adjustments of the 

 following birds: the egg laying of the old-world cuckoos; 

 the weaver bird of Africa; the flamingo; Apteryx; the 

 humming-birds. 



13. Make a study of the food of birds from Bulletin 

 No. 54, U. S. Department of Agriculture; or Judd's " Birds 

 of a Maryland Farm. ' ' 



14. Outline still other studies of the spring activities of 

 birds as compared with those of other seasons. 



15. Birds and the injurious insects. 



1 6. Classify the various services that birds render to 

 mankind. 



