422 PARASITISM AND DISEASE IN RUFFED GROUSE 



Although the stomach worm was found to be the most pathogenic species in ruffed grouse, 

 in no sense should it he iinafrined that infection is alwavs fatal. Considerahle indirect evidence 

 was gathered indicating that hirds may lose their parasites. In a number of instances healed 

 lesions were found in the proventriculus, characterized by extensive scar tissue. Since no worms 

 could he found in these birds, it is safe to interpret these findings as instances of recovery from 

 the parasitism. 



One case is worth mentioning here since it represented a rather unusual situation. Fifty- 

 three stomach worms were removed from a markedly enlarged proventriculus. Yet the bird, a 

 male, was in excellent condition for it weighed 622 grams (about 22 oz.). It is quite likely 

 that this infection may have been recently acquired and the deleterious effects of the ])arasi- 

 tism may not ha\e set in. The extent of the infection and the resistance of the host undoubt- 

 edly play a major role in determining whether or not the parasitism will evcntnallv kill the 

 bird. 



With the exception of one serious case of tick infestation, stomach worm infections were 

 the cause of death of all wild grouse without mechanical injuries that were found dead in the 

 field. The relative infrequency with which dead grouse are picked ii|> in the field gives this 

 fact even more significance. 



During the months of October and November. 19.33, 11 ruffed grouse were referred to the 

 Investigation by the Coiniecticut State Hoard of Fisheries and Game. Tlicse birds had been 

 submitted by hunters and other interested individuals whose attention had been attracted by 

 their abnormal behavior. Seven of this number were found to be heavily infected with the 

 proventricular worm. In all probability similar conditions prevail in other areas where this 

 parasite is found. 



In no sense, however, should it be assumed that ruffed grouse in all regions suffer from this 

 infection. Attention has been called to Boughton's" survey in Minnesota where not a single 

 instance of infection was encountered though .SOO birds were autopsied. Again. Muellers sur- 

 vey^' of niffcd grouse in New Hampshire indicated the absence of D. spiralis in any of 46 

 grouse examined. These records clearly indicate the danger of attempting to draw conclusions 

 from data collected in restricted areas. 



Incidence and Ini /lortance. Aside from being a {)rime factor in killing birds, stomach worm 

 infection undoulilediv adds indirectly to grouse niortalitv. Parasitized birds, especially in 

 the latter stages of the disease, may become so weakened that iheir flight is seriously impaired. 

 There is no doubt that predators may make short work of many such birds, if found. 



Infection with stomach worms takes place earl\ in the life of the chick but the worms are 

 not ajiparcnt until the second month when 8.2 per cent of the birds are infected. The incidence 

 rapidly rises to 29.1 per cent in the three to nine months ajjc ;^innii and ihcri >lMin|is sliarph 

 to 8.7 per cent in the spring and summer adults, 



Ihc high prccentage of infection of the young bird.-- ami the low pciccEilagc found in those 

 wild ha\(' survived the winter, raises a very pertinent question as to the reasons for this 

 change of incidence. It is problematical if the parasites are lost during that cold period or 

 whether the infected birds died and only those free of parasitism lived to be examined in 

 the spring and summer. The answer depends upon further research. If it were found llial 

 the stomach worm caused the death of most of the infedi-d \onng prou>c. llic laii;i' nuinliers 

 involved would explain one major source of loss. 



Since, in llic fall and winter adults, the incidence only rises to 1 I per cent, the further 



