46 Game Survey of the North Central States 



of territory otherwise unoccupied. It probably consisted rather of a local increase 

 from residual stock made possible by a succession of easy winters and favorable 

 breeding seasons. The reason for assuming this cause is, first, that there are no 

 records of migratory invasions or other long-distance movements on the part of 

 this species, and second, because I found only one report of a preceding abundance 

 in the "regular" quail range to the south and west of the irruptive area. (This 

 was Trempealeau County, beginning 1915.) If there had been a preceding 

 period of abundance in the regular quail range, the alternative assumption of a 

 true irruption would have been indicated. 



The significance of these irruptions does not lie in my particular hope that 

 the irruptive area can be converted to regular quail range, but rather in illustrat- 

 ing the extremely rapid increase which takes place whenever environmental con- 

 ditions allow. Repetitions of the event will doubtless occur in the future unless 

 the decline of agriculture in the Sand Area, which occupies the heart of the irrup- 

 tive area in Wisconsin, too far restricts available grain feed. 



Sudden changes in bobwhite populations which sound somewhat like these 

 Wisconsin irruptions have been heard of in Oklahoma, Nebraska (1880), and 

 Texas, and also in Michigan (1863), but as far as I know they have not been in- 

 vestigated. The fact that these areas of violent fluctuation all occur on the border 

 of the range of the species strongly suggests, however, that irruptive or cyclic 

 behavior may characterize the border of the range in many gallinaceous birds, and 

 that cycles and irruptions may be a property not of the species, but of the border 

 environment. 



Summary. In 368 samples of present quail population in the region, 

 densities of two to four acres and four to eight acres per quail occur with equal 

 frequency. This roughly is one quail per five acres, or two covies per 160 acre 

 farm. The most frequent density in Missouri is a little higher, and in Michigan a 

 little lower. 



The maximum density is one quail per acre, or 10 covies per farm. This is 

 evidently the saturation point of favorable range, and holds throughout the region. 

 It seems to hold for former times also. 



The maximum is not now attained in the Lake States, and seldom in any 

 but the riverbreak and hill types. 



Small areas closed to hunting in Missouri show sparser populations than 

 nearby open lands with better balanced food and cover. 



No State with a yearlong closed season was sampled with sufficient intensity 

 to justify a conclusion on its effects. 



Temporary concentrations of quail occur in fall and winter, especially in 

 Missouri. ~ 



Large temporary increases or "irruptions" occur on the northern fringe. 

 They are apparently the result of a succession of mild winters. 



