BIRD BANDING LINCOLN 337 



Table 4. — Percentage of males in handed ducks 



1 In the computation of percentages the figures have been carried to the second decimal, and the remaining 

 fraction, if less than 0.5, has been dropped, while if more than 0.5 the next higher unit has been adopted. 



It will be observed that in the case of the wood duck, there is a 

 more normal representation of what might be properly expected as 

 a sex ratio. As this handsome bird for 16 years has enjoyed com- 

 parative immunity from shooting, the conclusion seems to be fairly 

 well justified that overshooting has been responsible for the dispro- 

 portionate ratios in the other species. Possibly this is the correct 

 solution, but further study of the problem will be required before 

 the full significance of the data will be apparent. Nevertheless, 

 despite the seeming truth of the hypothesis that more males than 

 females are killed by hunters, it appears obvious the drakes now 

 outnumber the hens in a proportion that does not auger well for 

 the successful rearing of broods of ducklings. 



NONGAME SPECIES 



Banding problems dealing with nongame species, and which en- 

 gage the attention of the Washington staff of the Biological Survey, 

 relate almost entirely to distribution and migration. Contributions 

 to this subject by individual station operators obviously can have 

 only local significance for the reason that interpretation of the data 

 assembled from points over the entire hemisphere can be satisfac- 

 torily made only at the central office. There are, however, exceptions, 

 as occasionally a station operator will obtain an adequate quantity 

 of data from his own birds, or he may be able to coordinate the 

 activities of several widely scattered stations and so be placed in 

 possession of sufficient material to warrant interpretation. The 

 following examples, dealing with the evening grosbeak and the 

 Harris sparrow, illustrate the case in point. 



East and west migy^ation. — The general (and usually correct) 

 conception of bird migration is of a north and south movement. 

 In addition, for many j^ears we have been familiar with what is 

 known as " vertical migration " whereby mountain-dwelling species 

 obtain latitudinal changes in habitat b}^ the simple expedient of 

 moving down the mountain sides in the autumn and back aoain in 



