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 hnowy Owl is largely a 
