c 

 5 



CO 



-Q 



E 



3 



700 



600- 



500- 



400- 



300- 



200- 



100 



/A 



Autumn 



Winter 



Spring 



0-H— 

 1960-61 



T" ' I 1 



-I 1 1 1 I I 1 p 



65-66 



70-71 75-76 



Year 



80-81 



85-86 



Figure 4.4 



Estimated number of fawn mule deer on the 

 study area during autumn, early winter, and 

 spring, 1960-1988. 



season. Density also varied across the study area. For 

 example, a 21-km 2 area along the Missouri River on the 

 northwestern portion of the study area had mule deer densities 

 of 12-13/km 2 during autumn at population peaks. 



Log plots (Ln) of population one year (N t ) against 

 population the next year (N t . ) for early winter (Fig. 4.5) and 

 spring (Fig. 4.6) indicate the general cyclical nature of the 

 population and/or time-lag effects. These data and those in 

 Figures 4.1 through 4.4 also indicate, however, that time-lag 

 effects, if they occurred, were not uniform and that 

 population growth and decline occurred at a wide variety of 

 overlapping population densities. 



Population Growth Rates and Perspective 1930-1987 



The maximum observed annual instantaneous rates of 

 population growth (r = LnN t+1 - LnN t ) during the period 1960- 

 1987 varied from r=0.30 to r=0.38 during winter-to-winter and 

 spring-to-spring periods 1977-1980 and 1985-1987. Both 

 periods of highest observed population growth rates occurred 

 when harvest of antler less deer was not legal. However, those 

 growth rates did include harvest loss of adult males as well 

 as natural mortality of all sex and age classes. If no adult 

 males had been harvested during biological year 1979, but all 



85 



