THIRTIETH BIENNIAL REPORT 77 



"Duck disease," which has caused very serious losses of ducks in 

 the past, is one of the principal problems. This disease has occurred 

 in several of the western states and at different times has appeared 

 in at least five widely separated sections of California. The disease 

 has been diagnosed generally as "alkali poisoning." 



During the late summer of 1926 and again in the fall of 1927, ducks 

 were affected with a malady at Tule Lake, Modoc County, and Buena 

 Vista Lake, Kern County, respectively. The investigations made in 

 these instances indicate that alkali poisoning Was not the cause of 

 the disease, but that in all probability the mortalities may have been 

 produced by a biochemical action that was attendant to the decomposi- 

 tion of large amounts of organic matter in lake water. Laboratory 

 studies have not progressed to the extent that it is possible to make 

 positive diagnosis, but this work is now well under way and will be 

 carried on as rapidly as possible. 



The determination of the cause of "duck disease" is a very impor- 

 tant conservation problem. Knowledge of the cause of this disease will 

 probably suggest measures that can be taken to reduce the mortality 

 in future occurrences. It has been found that many of the afflicted 

 ducks would recover rapidly when placed on different water and food. 

 Some 800 of the sick birds were taken from Buena Vista Lake to a 

 nearby "duck hospital" that was established for the purpose. A large 

 percentage recovered to the extent that they were liberated after the 

 close of the hunting season. All of these ducks were banded before 

 being liberated. Since California is now committed to a program for 

 the acquisition of game refuges, it is essential that the cause or causes 

 of duck sickness be determined so that this information can be avail- 

 able when waterfowl refuges are selected. 



Studies have been started to determine the identification, life cycles, 

 and pathogenicity of the external and internal parasites of deer, quail, 

 pheasants, duck, geese and other species. Considerable progress has 

 been made in the work on ducks, geese and quail. A report on a blood 

 parasite (Haemoproteus, or bird malaria) of quail has been recently 

 published in California Fish and Game. Another problem that has 

 been given attention is the relationship of the parasites of nongame 

 birds to those of game birds. Studies of this kind help to solve the 

 problem of carriers and the ways in which parasites are distributed. 



A survey of the diseases of all game species is a large undertaking. 

 Scientists have not directed their attention to the pathology of game 

 to any great extent ; but little of this work has been done in this state. 

 In most cases it has been found that the normal condition of California 

 game is not known; this must first be ascertained as the "abnormal" 

 can not be determined until after the "normal" is established. 



A general program has been outlined but of necessity the work must 

 proceed slowly as the opportunity to secure specimens is usually sea- 

 sonal and much of the material must be collected during the open sea- 

 sons. It is planned to extend these investigations to include the study 

 of the diseases of all of the more important species, both in the field 

 and at the state game farm. These studies will disclose the effect of 

 disease on the abundance of game, suggest any measures that may be 

 taken to reduce the mortality, and furnish much information of scien- 

 tific value to conservation. 



