138 



the heavy decrease took place simultaneously in both species. Recovery began in 

 ruffed grouse a year sooner than it began in prairie chickens. This supports the 

 deductions drawn from the game survey. 



The highs and lows shown by both investigations compare with each other 

 as follows: 



Order of Mortality by Sex and Age. 



(a) No information sufficient to support conclusions was obtained. 



(b) Several hunters reported that most of the ruffed grouse remaining dur- 

 ing the last low were males, but their ability to distinguish sexes may be 

 doubted. If they were males, the observation would indicate differential survival. 



Length of Mortality Period. 



(a) The most reliable observations on single localities all agree that the 

 decimation in any one species in any one locality is seldom or never accomplished 

 within a single year, but usually requires at least three years. Recovery requires 

 a similar period. 



(b) The indications are that the year of heaviest mortality is always pre- 

 ceded and usually followed by at least one year of lighter loss. If there is an 

 exception to this, it is in snowshoe rabbits, which may sometimes fall off all 

 within a single year. 



Almost all of Grange's game observers reported both mortality and recovery 

 during the last cycle to have required three or more years each in their respec- 

 tive localities. This held good in both ruffed grouse and prairie chicken. 



The period of mortality over many localities has already been described under 

 the discussion of "lag." 



Season of Mortality. 



(a) Mortality as indicated by sick, dead, or heavily parasitized ruffed grouse 

 and prairie chicken took place during the last two cycles at various seasons of the 

 year. 



(b) Sick or dead birds seem to have been found mostly during the year of 

 heaviest loss, but heavily parasitized birds seem to have occurred at least a year 

 before and a year after. Sick or dead cottontails during the last cycle were found 

 mostly during early winter. 



