Voi. XXIT o . 7- •, 



,g(,^ J Recetit Literature. S^I 



division of the subject matter embraced therein. And then for the next 

 thirty pages, if, instead of merely 5831, there were added the name of the 

 group, as Aves : Casuarii ; Aves : Anseres; Aves : Passeres, etc., it would 

 certainly save the average user much vexation of spirit. To further facil- 

 itate use there should also be a separate index for each 'branch' under 

 'Special Zoology,' — one for birds, another for mammals, and so on 

 through the 29 sections, giving page references to each of the subdivi- 

 sions of the subject matter. The indexes should be placed at the end 

 of the sections, so that in this way each section would begin on an odd 

 page instead of in the middle of a column, as now, without any marked 

 break to catch the eye. — J. A. A. 



Cooke's ' Some New Facts about the Migration of Birds.' 1 — Professor 

 Cooke's 'new facts' are presented under the following subheadings (i) 

 ' Introduction ' ; (2) ' Causes of Migration ' ; (3) ' How do Birds find their 

 Way ? ; (4) ' Casualties during Migration ' , (5) ' Distance of Migration ' ; 

 (6) ' Routes of Migration ' ; (7) ' Are Birds Exhausted by a Long Flight .? ' 

 (8) Relative Position during Migration'; (9) 'Relation of Migration and 

 Temperature'; (10) 'Variation in the Speed of Migration'; (11) 'The 

 Unknown.' The 'Introduction' states briefly the present resources of 

 the Biological Survey for investigations of the migration of North 

 American birds, after nearly twenty years spent in the accumulation of 

 data. As to causes of migration, the author states: "The broad state- 

 ment can be made that the beginnings of migration ages ago were 

 intimately connected with periodic changes in the food supply, but this 

 motive is at present so intermingled with others unknown, or but imper- 

 fectly known, that migration movements seem now to bear little relation 

 to the abundance or absence of food." 



Under 'How do Birds find their way V he admits that "among day 

 migrants sight is probably the principal guide," and that it "undoubtedly 

 plays a part in guiding the night journeys also"; but he believes they 

 also possess a power, whatever its nature, that "may be called a sense of 

 direction," which serves to guide them unerringly over ocean wastes. He 

 further says: "A favorite belief of many American ornithologists is 

 that coast lines, mountain chains, and especially the courses of the 

 larger rivers and their tributaries, form well-marked highways along 

 which birds return to previous nesting sites." That many birds reared 

 in Indiana, Illinois, and elsewhere to the northwestward visit South Caro- 

 lina and Georgia in their fall migration has, how-ever, long been known. 

 "The truth seems to be," he affirms, "that birds pay little attention to 



1 Some New Facts about the Migration of Birds. By Wells M. Cooke, 

 Assistant Biological Survey. Yearbook U. S. Depart. Agriculture for 1903, 

 pp. 371-3S6. 



