10 BULLETIN" 21*7, U. S. DEPARTMENT OF AGRICULTURE. 



drowned. It also developed that very weak birds should be separated 

 from the others. Under more favorable conditions the percentage 

 of recoveries could be markedly increased. California sportsmen 

 will be interested to know that at present this appears to be the only 

 measure that will prove successful on Tulare Lake. It is even possi- 

 ble that birds once cured may become to a greater or less extent im- 

 mune, and will not readily be affected again. 



In order to obtain data on this possible immunity and on the sub- 

 sequent longevity of birds which have recovered from the poisoning, 

 aluminum bands were placed upon the legs of 270 of the birds released 

 during the past summer. Each band bears a number on one side 

 and on the reverse the inscription "Notify U. S. Dept. Agr., Wash., 

 D. C." By this means the birds may be identified should any of 

 them be found or captured. 1 Already reports have been received 

 concerning more than 20 of these birds. Should more of these bands 

 be secured it is hoped they will be forwarded to the Department of 

 Agriculture with full information as to date taken and attending 

 circumstances. 



i Valuable information in another line of investigation will be forthcoming from these bands. At present 

 knowledge of the routes of migration followed by waterfowl is based upon observation as to the dates of 

 arrival or departure of the birds in various localities. These, properly tabulated, show the movement of 

 the species in question as a whole. The actual lines of flight pursued by individual birds are almost entirely 

 unknown. The importance of information on this point can not be overestimated. 



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