410 



PARASITISM AND DISEASE IN RUFFED GROISE 



PARASITISM AND DISEASE IN WILD GROUSE 



The fact that all parasites and patholopiral conditions are not found in all places, at all 

 times and in birds of all ages, leads to speculation as to the causes which influence the distrib- 

 ution and effect of various infections. Here many interesting questions arise: — Is the inci- 

 dence of parasitism in grouse the same in different regions of the State? Does it vary from 

 year to year, or from season to season? Do adult birds have the same parasites as the imma- 

 tures and are they found in the same numbers? \\ hat diseases observed in captive birds are 

 found in the wild? Are soil and climatic conditions factors influencing disease? 



Wherever the information accumulated during the Investigation appeared reasonably ade- 

 quate, it has been analyzed with these problems in mind. 



Before the picture is considered in detail, it is informative to gain an overall impression. 

 Based on the collection of a substantial number of wild birds from each region of the State, 

 for each season and covering a period of ten years, table 64 was compiled showing the relative 

 occurrences of parasites. Examination of this reveals that these are only four internal para- 

 sites whose incidence exceeds five per cent. It is also apparent that their relative positions 

 differ, depending on whether they occur in adults or chicks. 



T\BI,K r.l. 



HKIATIM-: orrtniHFxrE of PvnvsiTRs i\ Yoii\r, and vdtti.t r.nousE 



I.\ M:\V ^OliK l')31-l')41 



* The lapcworm commonly found in chicks is a large form known as Railtietina letragona, while the one listed from adults is 



a fine, thrrad-likc typ*- known a* Hymcnnlrpix mirrofis. 

 A Sincr toller flics arr Koinetimrt rulloqiiinlly kniiwn ns "flying tirkn". it should he {lointril out that they are winged insects 



and that the term tick should only be al>l>lici4 to tlic more sedentary, wingless ectnpnrasitic relatives of the spiders and mites. 



One might conclude from the table thai intestinal wtirms. which occur in such a high per- 

 centage of the birds, arc of the greatest importance. This \ iew. however, can not be siil>staiili- 

 ated when the ability of the parasite to produce disease is considered. The inlestinal wDrrn 

 ( Ascariilia honasdc) . on account of its size ami fretpiencN of occurrence, is the one most com- 

 monly obserxcd by si)ortsmen and which the\ arc iikcK to regard as a serious enemy of grouse. 

 The organism which is, however, most capable of producing disease is the seldom seen stomach 

 worm which occii|iies luil fourth place in frctiiicniy of occurrence in chicks and second 

 place in adults. 



