74 



DEPARTMENT OF FISH AND GAME 



Laboratory and field studies on the disease indicated 

 the importance of aquatic insect life and the role of 

 fly larvae in the epidemiology of the disease. It was 

 found that a single fly maggot could contain enough 

 botulinus toxin to cause illness in a pheasant, and three 

 to cause death quickly. 



That ducks do consume maggots has been shown 

 by examination of the gizzard contents of ducks sick 

 or dead from the disease. A high percentage of shore 

 birds found infected have fly larvae in their gizzards. 

 This indicates that the carcasses left in a botulism area 

 are a factor in the continuation and spread of the dis- 

 ease. One of the vital procedures followed in botulism 

 control is the removal of these carcasses from the area. 

 This is particularly important in outbreaks among 

 game farm pheasants. 



Fowl Cholera 



There were three minor outbreaks of fowl cholera 

 during the biennium. In the delta area, 406 swans by 

 actual count were victims of the disease. Just outside 

 Gray Lodge Refuge about 1,000 birds, primarily coot, 

 succumbed. On the Colusa Federal Wildlife Refuge an- 

 other 2,000 birds, of which 1,800 were coot and 200 

 were widgeon, pintail and mallard, were lost. 



Control measures consisted principally of removal 

 of carcasses. It was found that infected gulls, swans 

 and geese were instrumental in spreading the disease 

 to other areas because of natural resistance which 

 enabled them to survive long enough to fly consider- 

 able distances. 



Department personnel could not have created a bet- 

 ter clinical laboratory test of this than one they ob- 

 served in the field. As they watched a flight of snow 

 geese, one set its wings and glided to earth at Honey 

 Lake, Lassen County. The bird was penned and died 

 in about four hours. Game laboratory diagnosis tabbed 

 the cause of death as pasteurellosis— fowl cholera. It 

 \\ as the first case ever found at Honey Lake, an area 

 not considered endemic to fowl cholera, indicating the 

 bird came from an infected area, possibly from the 

 delta which experienced an outbreak at that time. 



Aspergillosis 



The largest outbreak of aspergillosis, a disease in- 

 volving pneumonia-like symptoms, was discovered 

 near Woodland where 400 ducks were victims. 



The department laboratory traced the outbreak to 

 a rice hull dump where the ducks had fed on moldy 

 rice remaining in hulls. The dump owner agreed to 

 burn his hulls continuously as he dumped them. After 

 the burning there \\ as no repetition of the disease. 



Trichomoniasis 



During the biennium outbreaks of trichomoniasis 

 in doves were investigated in the vicinity of San 

 Diego, centered in the metropolitan area. Incidence of 

 infection was as high as 10 percent of the population. 

 The infection appears in the spring and dies out bv 

 fall. Prophylactic medication with the drug enheptin 

 was applied in the late spring of 1956 in dove concen- 

 tration areas. 



Economic Poisons 



During the biennium investigations were begun on 

 the problems of economic poisons on wildlife. These 

 studies v\'ere mainly field investigations on incidence 

 of losses. Contact was made with agencies employing 

 poisons and sprays, and attempts were made to cor- 

 relate losses with the use of these agricultural sprays 

 and poisons. With the increased use of these insecti- 

 cides and poisons, problems continue to arise in re- 

 gard to their effects on wildlife. 



Nutritional Studies 



During the biennium comparisons were made of 

 the relative eflfects of net digestible protein and 

 digestible carbohydrates and fats and their impor- 

 tance in deer survival. An expanding program is being 

 undertaken to study the effects of environment on 

 deer. These studies include the effects of weather and 

 climate on the deer and their movements, as well as 

 the effects of these and other stresses on the well-being 

 of the herds, and the interrelation of all of these fac- 

 tors, including nutrition, on the problem of deer losses 

 during the w inter. 



Food Habits of Wildlife 



Continuing studies were made of the food habits of 

 game and predators. This knowledge of the food 

 preferences of the game species becomes a valuable 

 management tool in assessing range conditions. 



In addition, food habits determinations were made 

 for the game departments of several western states. 

 This service has been paid for by these states on a 

 cost basis. 



