THE DUCK SICKNESS IN TJTA II. 17 



The great prevalence of the duck sickness beginning with L910 

 must be attributed to the lessened supply of water in the streams. 

 Coupled with this, however, must be other factors not wholly under- 

 stood. It seems probable that changes in the water level of Great 

 Salt Lake may be prominent among these. Through the courtesy 

 of Otis West, of the Engineering Department of the Southern Pari fie 

 Railroad, there is available a graph showing oscillations in the lake 

 level between the years 1850 and 1914. This chart shows a steady 

 decline in the water level from 1886 to 1902. From 1902 to the 

 beginning of 1906 the water remained about the same, except for 

 the usual rise and fall that occurs each year. A rapid rise began 

 then, so that the lake at its highest point in 1910 was nearly 8 feet 

 above the minimum in 1905. From 1910 there was at first a slight 

 drop, then the level was more or less stable until 1914. In 1914 and 

 1915 the water lowered again somewhat. 



The soil below the surface in the Bear River marshes is strongly 

 saline, and the ground water permeating it is heavily impregnated with 

 salts. Though water in the lower channels and bays was fairly fresh, 

 a hole 10 to 15 inches deep at the water's edge usually yielded an 

 abundance of strongly saline water. The great rise in the lake 

 water would, in this region of low elevations, cause a correspond- 

 ing rise in the water table of the soil and bring salines in quantities 

 to the surface or near it, perhaps for a considerable distance inland. 

 Thus poisonous elements might be available in abundance in areas 

 where ducks formerly had fed with impunity. The effect of the 

 rising salts in the soil is readily seen in the great areas in which the 

 rushes have been killed in the lower portions of the marshes that 

 border the lake front. In many places there remain of the former 

 growths merely the bulbs with short projecting stubs, or again the 

 plants may be newly dead. 



Ducks may establish a slight immunity to the alkali when they 

 gradually become accustomed to it in d^uted amounts. In the spring 

 numbers of sick birds were said to be found in the lower channels on 

 Bear River when the birds returned from the south. This was verified 

 when many bodies were seen on the banks of the overflows in May 

 of 1915 and 1916. These birds must have died during the early 

 spring, otherwise the spring water and the ice would have carried 

 them away. Following this there are practically no sick ducks until 

 the first part of July. If che water rises in May or June a good 

 many young avocets and stilts are killed in the salt pools formed on 

 the flats, and occasionally sick coots or young ducks are found. In 

 May, 1916, there was a curious instance of the way birds seemingly 

 exempt from this trouble may be affected. A large flock of cliff 

 swallows was driven down to the flats about Duckville by a heavy 



