8 BULLETIN 936, U. S. DEPARTMENT OF AGRICULTURE. 



end of South Baj^, and a week later there were many hundreds. 

 Birds that were shot for examination had the genital organs greatly 

 enlarged, showing that they had finished breeding recently. They 

 began molting into the eclipse plumage at once, and the mud flats 

 where they rested during the day were strewn with cast-off feathers. 

 In 1916 pintails appeared even earlier in the season; on June 7 

 about 100 drakes were found in South Bay, while on the following 

 day their numbers had been augmented to approximately 1,000. 

 On June 14 a flock of male pintails in the region known as Lands 

 End was estimated to contain between 2,500 and 3,000 birds. With 

 these were only two or three females. As it was estimated that in 

 1916 there were only 130 pairs of breeding pintails in this entire 

 marsh area, it will be seen that there was a great influx of males at 

 this time. Where these summering birds nest is of course uncertain, 

 but they must gather here from great areas that apparently lie 

 largely outside of Utah. Though the pintails arrive first, they are 

 soon joined by many mallards and shovelers, of which a part come 

 from the surrounding marsh and a part from other regions. These 

 males steadily increase in number and, joined later by broods of 

 immature birds, form great banks of ducks that rest during the day 

 on the shallows covering the mud flats. 



The Canada geese follow a different procedure in their molt. They 

 nest early, and as soon as their young are strong enough they take 

 them far down on the flats. The adult birds are more or less in 

 evidence until about May 25, when most of them disappear. At this 

 season adults and young frequent the great growths of rushes 

 (Scirpus paludosus) in the lower marsh, and while hidden here the 

 adults molt their flight feathers. In 1916 a number of families of 

 geese lived in the lower part of Hansens Island through this period 

 of molt. In feeding they apparently ranged over considerable areas 

 and at night came into dense green rush growths near the open bays, 

 where they slept close together on small hummocks. At this season 

 they were warier than ever and seldom was one seen. In the heavy 

 growths of rushes their roosting places, marked by broken, trampled 

 vegetation and great piles of excreta, were found frequently; and 

 goose tracks were often seen in small channels and runs through the 

 marsh, so fresh that mud stirred up as the geese passed was still held 

 in suspension in the water, but the birds themselves kept well hid- 

 den. By molting at this early date the wing feathers of the adults 

 were renewed by the time the young were able to fly, and old and 

 young were thus able to remain together. Geese begin to reappear 

 on the marsh between Juty 1 and 4, and by July 10 small flocks with 

 their musical fall notes were again a familiar morning and evening 

 feature of the life of the marsh. 



