194 THE MIGRATIONS OF BIRDS 



Migratorial movements among some of the native 

 ducks of southern South America are regular with 

 the coming of colder weather. Males of some of 

 these have the habit, which has been noted for other 

 species, of abandoning the female so that these males 

 band in large flocks in late summer. Their migra- 

 tion may come early: during the first week in No- 

 vember, in 1920, I saw large numbers of South 

 American pintails come from the south into a region 

 of marshes and lagoons in the eastern part of the 

 Province of Buenos Aires, following a tremendous 

 storm of wind and rain that flooded the country. 

 This flight continued morning and evening for three 

 days and included many thousands of birds. The 

 ducks travelled in small or large flocks, which flew 

 steadily to the northward only thirty to sixty yards 

 above the earth. During one forenoon I estimated 

 the total number that passed my camp at between 

 15,000 and 20,000, and believed that fully 95 per 

 cent of them were males. Those that I shot were 

 still in full breeding condition, indicating that they 

 had only recently deserted their mates. The main 

 flight comes later in the year, from March to May, 

 when the hosts of young bred in the south come up 

 to winter in the northern lakes. At this season the 

 birds are found in tremendous numbers in suitable 

 localities. 



