WILD DUCKS OF THE BEAK RIVER MARSHES, UTAH. 



Species. 



Redhead 



Cinnamon teal 



Mallard 



Shoveler, or spoonbill 



Gadwall 



Ruddy duck 



Pintail 



Estimated 



number of 



breeding 



pairs. 



1,725 

 800 

 300 

 250 

 200 

 175 

 130 



Green-winged teai 



Widgeon 



Blue- winged teal 



Scaup duck, or bluebill . 



Total 



3,650 



1 Not included in total. 



As a conservative estimate each pair of clucks may be expected to 

 rear 5 young, and as the average brood varies from 7 to 12 indi- 

 viduals this allows for considerable mortality among ducklings. 

 Adding the survivors to the original pair, the total number of native 

 birds on this marsh at the end of the breeding season should be 

 approximately as follows : 



Species. 



Individ- 

 uals. 



Species. 



Individ- 

 uals. 





12,075 

 5,600 

 2,100 

 1,750 

 1,400 

 1,225 





910 







350 







70 







70 





Total 







25, 550 









In addition to the ducks, about 100 pairs of Canada geese breed 

 on these marshes. Allowing 3 young as the average number brought 

 to maturity by this species, there would be a total of 500 birds at 

 the close of the season. The nesting season for these geese is prac- 

 tically over by May 15, and their • numbers were estimated from 

 observations made before they disappeared in the lower marshes 

 for their annual molt. 



The figures given above are approximations, but it is believed 

 that they are not far from the truth. From them it is learned that 

 this marsh area produces between 25,000 and 30,000 ducks in the 

 average season, as in 1916. The question may arise as to the pro- 

 priety, in arriving at a total, of adding the original pair of birds 

 to the young produced. It is probable that a large part of the 

 adult ducks that die from natural causes (as opposed to shooting) 

 do so toward the close of the breeding season and during the molt 

 that follows. Exhausted by the calls made upon their strength by the 

 needs of the nesting season, they have not sufficient vitality to carry 

 them through the annual molt that takes place as soon as they are 

 freed from their parental duties. In the estimates^ however, suffi- 

 cient allowance has been made for mortality among the young to 

 cover losses among the adults as well, so that the totals given should 



