WILD DUCKS OF THE BEAR PJVEE MARSHES, UTAH. 15 
importance to merit attention. Any of the ducks will turn to animal 
matter for sustenance when it is readily available and snap up in- 
sects or even small minnows that may be accessible, though normally 
the bulk of their food may be vegetable matter. There are. however, 
at the mouth of Bear Eiver. a few species belonging to the animal 
kingdom present in such numbers as to form a food supply upon 
which some ducks feed to large extent during part of the year. Be- 
low the lower end of the marsh, where saline conditions are so pro- 
nounced as to prevent vegetable growth, are great quantities of the 
immature stages of several species of alkali flies (Ephydra hums, 
E. suhopaco. and E. gracilis). The larva? and pupa? of these insects 
form great masses in the water and the cast-off pupal cases are 
washed up in windrows that frequently extend for miles along the 
shores of the lake. "With them in equal numbers, or possibly ex- 
ceeding them in abundance, are the fairy or brine shrimps (Artemia- 
fertilis). These small, almost transparent creatures are so abundant 
that they form veritable clouds in the water, and these, with the fly 
larva? and pupa?, form an important source of food for certain 
species of ducks and also for various shorebirds. 3 After the summer 
molt spoonbills, or shovelers. begin to gather in the lower bays, and 
by September 1 are present in considerable numbers. The flocks 
continue to increase, until by October 1 it is not unusual to see close 
banks of these birds 2 miles or more long and from a fourth to half 
a mile deep. At this time the birds feed largely on the brine shrimps 
and on alkali-fly larva 1 and pupa?. Thev remain here until finally 
driven out by the freezing of the fresh-water bays, to which they 
resort to drink. Usually the shoveler is thin and poor in body, but 
birds killed here were exceedingly fat. so that while this species 
ordinarily is considered a mediocre table bird, those killed on the 
lower bays were good eating. 
During October the spoonbills were joined by great flocks of 
lesser scaup ducks (Mariia affinis) and later by a considerable num- 
ber of golden-eyes, or whistlers {Clangula clangula americana) , and 
all subsisted largely upon the brine shrimps and the immature 
alkali flies. These ducks were found regularly only in this part of 
the bay and it was unusual to see them higher up. Ducks shot in 
this lower area often were crammed with food, so that when the 
birds were ^ncked up by the feet brine shrimps and. fly larva? oozed 
in a slimy mass from their throats. It is hardly necessary to point 
out the value of these supplies of animal food as an additional at- 
traction to bring wild ducks to this marsh. 
3 Cf. Wetmore. A.. On the Fauna of Great Salt Lake : Amer. Naturalist, vol. 51, pp. 
753—755, 1917. 
