56 FISH AND GAME COMMISSION 



with these parasites. Liver flukes have been found to be common in deer 

 in areas where these parasites are a serious problem with cattle and sheep, 

 but in areas where domestic livestock are not infected, deer also are 

 free of this parasite. A type of papilloma, or skin tumor, occasionally 

 seen in cattle, has been observed on several deer from Marin County. An 

 extensive survey was conducted to determine the incidence and possible 

 importance of a round worm parasite that occurs in the feet of deer. 

 Although large percentages of deer were found to be infected in many 

 areas of the State, it did not seem that these parasites were causing 

 much suffering or debilitating results in the infected animals. Studies 

 were conducted on the nasal bots of deer and the fly responsible for this 

 infection was determined. 



Examination of a number of antelope during the special hunting 

 seasons revealed that although several types of parasites occurred in 

 these animals, they were in such small numbers as to be causing no harm. 



Further investigations were made in an effort to determine the 

 source of a so-called "iodine" condition of ducks in the lower San Fran- 

 cisco Bay area. J. B. Swim, toxicologist for the city and county of San 

 Francisco collaborated in this study. No iodine is involved in the con- 

 dition although the ducks develop a medicinal odor somewhat resembling 

 iodine. This odor is readily distinguishable from the sewer smell which 

 develops in some ducks on the bay which feed extensively at the outflows 

 of several sewer disposal areas. 



This condition in the ducks was first observed by hunters and game 

 wardens in the years following cessation of extensive feeding of grain 

 by the various duck clubs in the area. Apparently the shortage of food 

 forces the ducks remaining in the area to consume much algae which 

 grows particularly abundant in some of the marshes and salt ponds 

 bordering the bay. When dried, this material gives off the characteristic 

 odor. When fed to healthy ducks, these birds develop the odor which 

 rapidly permeates their muscle tissue. Ducks which feed on this mate- 

 rial sometimes can be recognized immediately by the odor when shot, 

 but in many cases the sickening aroma is not evidenced until the flesh 

 is heated or while cooking in the oven. The condition causes no noticeable 

 harmful effects on the birds ; they remain in good flesh and apparently 

 recover when they leave the area or cease feeding on the algae. The chief 

 problem presented by this condition is the fact that many hunters dis- 

 card such birds when them come to bag, thus creating a considerable 

 waste. 



The program of studies on the blood and other parasites of quail 

 has been continued, and now is expanding to include similar investiga- 

 tions on the diseases of mountain quail and pheasants. Field samples 

 obtained chieflly through the cooperation of the Associated Sportsmen of 

 California and other hunters have added much to our knowledge of the 

 distribution of some of the parasites of quail. Laboratory studies on fly- 

 borne Haemoproteus-malarm showed that infected birds can harbor the 

 parasites in their blood continuously over a period of several years with- 

 out being subjected to possible reinfection and that the large parasitic 

 fly which occurs on the birds is capable of transmitting the infection just 

 as the smaller species of fly was known to be a vector. 



Collateral with our studies on the diseases of game birds, comparable 

 information is being obtained on other species of birds. It was found that 



