enclosure containing several hundred flies and 

 toxin placed above the reach of the birds. Almost 

 immediatel}', the ducks began to pursue and cap- 

 ture flies, but their aggressiveness in this respect 

 varied among individuals. When toxin taken by 

 flies was in the form of a laboratory culture of 

 Clostridium botulinum type C, the unprotected 

 pair of birds died, as did two more unprotected 

 pairs introduced into the pen on 2 successive days. 

 The pair protected with antitoxin survived. 

 Wlien flies acquired toxin from feeding on decom- 

 posing duck carcasses, two of four unprotected 

 birds died, one became paralyzed but recovered, 

 and the fourth was not obviously a fleeted. Four 

 protected control ducks remained free of symp- 

 toms throughout the experiment. 



Toxin-laden blowflies are now considered to be 

 important enough among factors contributing to 

 botulism outbreaks to warrant more extensive in- 

 vestigation in epizootic areas. 



Mal<iria infecti-ons in waierfowl. — During 19&i, 

 an estimated 450 of 600 goslings at the Seney 

 National Wildlife Refuge died, presumably of 

 LeucocytozoMu a malaria-type disease. Further 

 work conducted in an effort to detennine the spe- 

 cific black flies involved in transmission of the 

 disease was aimed at elucidation of their distribu- 

 tion, abundance, and biology in development of 

 biological control methods. Techniques were de- 

 veloped for the collection and transportation of fly 

 eggs for studies in the laboratory, and successful 

 rearing from egg to adult has been accomplished. 



Research was also done on the prevalence of 

 Pla.sinodium circumflexuin. a recently isolated, 

 mosquito-borne malaria in Canada geese. It was 

 demonstrated by inoculation of susceptible do- 

 mestic geese with blood from wild donors that over 

 60 percent of 89 wild Canada geese at the Seney 

 Refuge carried the infection. A similar .study of 

 50 Canada geese from the flock at the Patuxent 



The Iowa Unit, cooperating with the Department of Veterinary Medicine. Iowa State University, has made extensive 

 blood studies of wild and game-farm pheasants. Graduate- student shown drawing blood from pheasant in lab- 

 oratory. Studies of this nature permit checks for disease antibodies and blood parasites and identification of 

 blood types in pheasant populations. (Photo by Arnold O. Ilaugen) 



55 



