37 ELEMENTARY ZOOLOGY 



autumn. Notes on the kinds of days, as stormy, clear, 

 cold, warm, etc., on which the migration seems to be 

 most active ; on the greater prevalence of migratory flights 

 by day or by night; on the height from the earth at which 

 the migrants fly, etc., are all worth while. The Division 

 of Biological Survey, U. S. Department of Agriculture, 

 keeps records of notes on migration sent in by voluntary 

 observers and furnishes blanks to be filled out by each 

 observer. A suggestive book about migration, and one 

 giving the records for many species at many points in the 

 Mississippi valley is Cooke's "Bird Migration in the 

 Mississippi Valley." Migration is discussed in most bird- 

 books. 



Feeding habits, economics, and protection of birds. 

 The feeding habits of birds are not only interesting, but 

 their determination decides the economic relation of birds 

 to man, that is, whether a particular bird species is harm- 

 ful or beneficial to man. Casual observation shows that 

 birds eat worms, grains, seeds, fruits, insects. A single 

 species often is both fruit-eating and insect-eating. Do 

 fruits or do insects compose the chief food -supply of the 

 species ? To determine this more than casual observation 

 is necessary. The birds must be watched when feeding 

 at different seasons. The most effective way of determin- 

 ing the kind of food which the bird takes is to examine 

 the stomachs of many individuals taken at various times 

 and localities. Much work of this kind has been clone, 

 especially by the investigators connected with the Division 

 of Biological Survey of the U. S. Department of Agricul- 

 ture, and pamphlets giving the results of these investiga- 

 tions can be had from the Division. It has been distinctly 

 shown that a great majority of birds are chiefly beneficial 

 to man by eating noxious insects and the seeds of weeds. 

 Many birds commonly reputed to be harmful, and for that 

 reason shot by farmers and fruit-growers, have been 



