4 MUSEUM BULLETIN NO. 28. 



known fact that periodically these hares contract a contagious disease 

 that practically exterminates them over wide ranges of country and 

 which sometimes spreads to the Jack rabbit and other prairie rabbits. 

 Thus the rabbits show a steady annual increase until they become very 

 numerous, then a sudden reduction to very few. In times of rabbit 

 abundance all the flesh-eating animals of the north, including the 

 Goshawk, revel in plenty and increase in number. When this food 

 supply is cut off hunger and starvation is their lot and their attention, 

 rendered keen by need, is turned to sources of supply neglected when 

 easier prey is procurable. At such times grouse of all kinds suffer most 

 severely. The grouse of the northern localities are soon exhausted and 

 the Goshawk and large owls are forced out into new fields. They then 

 come down in the southern prairie provinces in unusual numbers and 

 continue there the work that they began in the north. The winter of 

 1916-17 was the culminating fatal winter for rabbits and reports came 

 in from throughout southern central Canada of the unusual abundance 

 of "large grey hawks" and "large horned owls." The consequence was 

 that the summer of 1917 was marked by a scarcity of grouse of all kinds 

 Prairie Chicken, "Square- tails," and Ruffed, Spruce, and Blue Grouse. 

 Had this scarcity been primarily due to overshooting, as would be the 

 first natural conclusion, there would have been occasional small localities 

 which the sportsman had overlooked or had been unable to reach and 

 results would have varied in different parts of the country. Grouse 

 conditions, however, were similar over the whole country and out of the 

 way parts of the Red Deer badlands that are difficult of access and the 

 national parks where no shooting is allowed were as barren of game as 

 the immediate neighbourhood of settlements where sportsmen were plen- 

 tiful and active. It has been suggested that poisoned grain set out for 

 gophers might have been instrumental in killing the Prairie Chicken. 

 However, it appears from the reports of officers of the United States 

 Biological Survey, who are at work upon the problem of controlling rodent 

 pests, that they have seen no evidence of grouse poisoning from this 

 source and that this group of birds seems extraordinarily resistant to the 

 poisons usually used. Other evidence also proves that this cannot be 

 the primary cause of the grouse disappearance, for they are as scarce 

 to-day in areas where there has been no poisoning of gophers as else- 

 where. However, the blame for this destruction should not be placed 

 altogether on the Goshawks as they were helped by the Horned and 

 Snowy Owls and the coyotes, foxes, and lesser vermin. In the early 

 autumn and spring probably the owls mentioned must be considered, 

 but in all likelihood as soon as winter comes with sufficient snow for the 

 grouse to bury themselves in at night the importance of these nocturnal 

 birds is considerably reduced; and though the Snowy Owl is largely a 



