Eighteen (29%) of 62 females resident in areas of low 

 topographic relief died. Only 1 (3%) of 37 migratory females 

 and 8 (9%) of 85 females resident in areas that contained 

 steep terrain with north- and south-facing slopes died. 

 Females resident yearlong in areas of low topographic relief 

 not only died at the highest rate overall, but also in each 

 winter. When they were compared to all other females that 

 used steeper terrain, whether resident or migratory, the 

 difference in mortality rates remained significant (X-13.8, 

 P<0.001, 1 df ) . 



There are several probable explanations for the higher 

 winter mortality rates of females resident in areas of low 

 topographic relief than for other females. During late summer 

 and autumn, succulent forage was scarcer in areas of low 

 relief than in steeper terrain both because of more intensive 

 cattle grazing and because the shallow drainages were less 

 protected from the desiccating effects of sun and wind. These 

 areas also had less topographic and microsite diversity and 

 therefore less diversity of plant species and plant phenology 

 than areas of greater topographic relief. Thus, deer resident 

 to areas of low topographic relief had shorter periods of 

 access to high quality forage than other deer and females 

 probably experienced more lactation stress, especially during 

 dry summers. During winter, these deer had to spend more 

 energy moving through deeper snow because of the lack of bare 

 south-facing slopes and large, thickly-timbered, snow- 

 intercepting north-facing slopes. Also, they did not have 

 access to large, warmth-radiating south-facing slopes and the 

 diversity or quantity of winter forage available in steeper, 

 more diverse areas. Overall, deer resident to areas of low 

 relief had a shorter period of positive energy balance and a 

 longer, more severe period of negative energy balance than 

 deer occupying areas with more diverse topography. They were 

 more susceptible to all sources of natural mortality including 

 coyote predation and malnutrition. 



We expected that in areas of low relief, fawn production 

 and survival should be relatively low, and total deer numbers 

 lower than on areas with greater topographic relief. This 

 generally appeared to be the case, but because of the 

 variability in movements of migratory deer between areas of 

 low and high relief, interpretation of the data was difficult. 



At least some of the higher surviving migratory females 

 had not moved to areas of steeper terrain at the time of some 

 early winter surveys and some had not moved back to areas of 

 low relief at the time of some spring surveys, thus fawn 

 survival and total deer numbers in areas of low relief was 

 difficult to determine. Also, if females in low relief areas 

 died at a greater rate than other females during winters of 

 high mortality, fawn survival for original numbers of females 



168 



