412 



PARASITISM AND DISEASE IN RUFFED GROUSE 



ill both wild and captive grouse. In the former it was encountered only a few times and in 

 widely separated parts of the State. 



Inflammation of the crop, intestine and gizzard, associated with infections by crop worms, 

 tapeworms and gizzard worms respectively, were not of a serious nature and no deleterious 

 effects on the well-being of the birds were observed. 



Certain variations due to geographical, seasonal and age differences have become apparent 

 during the course of the Investigation. These indicated that a table of incidence based on 

 total collections presented information of an extremely general nature. To take but one ex- 

 ample, the incidence of the stomach worm ( Dis pharynx) in all birds over three months old is 

 listed at 12.7 per cent. Subsequent analysis revealed that this parasite was almost entirely 

 absent from the .Adirondack region, appearing only occasionally on the periphery. Further 

 examination of the data showed that 29.1 per cent of the birds of the year (from three to nine 

 months old) were infected, but adults taken during the spring and summer had infections in 

 only 8.7 per cent. Accordingly, in order to complete the picture, the variations due to age of 

 the birds, seasons and regional distribution are discussed in the following sections. 



Factors Affecting Different Ace Classes 



That certain organisms commonly parasitize adults while others are more liable to be found 

 in young hosts, has been observed frequently during the course of recent pathological examin- 

 ations. This phenomenon is clear-cut with reference to certain of the parasites encountered in 

 grouse but is less well defined for others. Incidences of the commoner parasites in the differ- 

 ent age classes are shown in table 67. 



TABLE ()7. INCIDENCE OF THE COMMON PARASITES OF GROUSE IN NEW YORK BV 



AGE CLASSES— 1931-19 a 



* Thp romliineil inculetifr of inlrrnal parasites indicated here fur iho three age claniie* cuverine the chick period (under 3 



nioritlia) diflern iili|;Iili\ from ihr ligiirrft in tab If 6i hcL-ausc rrtain specimens included there, although they were known to iall 



witliin this run^c i-<iuld not Ix- I'luRsilU-d by niunth. 

 A The laiirMitTnin refiTrril to in birds under three months of a^e are R, tetragona; thoKe in birds older than three months, 



//. microps. 

 t Tbf percenlaites given for stomach worms are based only on rolled ions from those regions of the State in which DispharjrmM 



occurs. 

 X On account of certain collecting procedures, described elsewhere, depemlablc data on incidence of eilernal parasites is not 



available for the (all and winter months. 



Parasitism \u rliicks urulrr two weeks of age is relatively infrequent. l>ut very soon there- 

 after ta|»e\v(>rms and coccidia are found. Botli of these are relatively al)undant in June and 

 July l>ut infrequently found by August. Most of the tapeworms found in these young birds 

 are a large form (Raillietina tetragona) also found in domestic poultry. It is presumed that 



