Fawn Mortality!!!

[Cougeyes]

In terms of population maintenance, loss of 80% of the fawns from birth to 1 year old will result in a stable population (with pregnancy rates of 1.5 fawns/doe).  By contrast, loss of more than 15% of does annually leads to a declining population.  Buck mortality does not affect population growth rates until buck numbers get so low that pregnancy rates are affected. 

In terms of effects on the deer and elk populations, it is predation on adult females that most affects populations.  IMHO, therefore, cougars are the predators with the greatest affect on populations where cougars are abundant.  That includes nearly all of the timber lands and national forest lands where the majority of hunting occurs.

Black bears are incredibly efficient fawn and calf predators for a couple of weeks every year.  They can definitely suppress populations when they are low.  Coyotes can have a major effect when there are prolonged crusted snow conditions.  Effects vary by region, but at a statewide level cougars get my vote for the greatest impact to populations through predation on adult does and cows. 

I don't think 2,000 cougars is too far off the mark.  Assume 60% of the postseason populations are adult cows and does, with fecundity rates around 50 calves:100 cows for elk, and 150 fawns:100 does.  With a postseason population of 55,000 elk and 300,000 deer statewide, we have a June population including newborns of 71,500 elk and 570,000 deer.  Assuming 50 kills/year/cougar, and 50% kill composition of adults and newborns, and proportional killing of elk and deer, 2,000 cougars will kill 100,000 deer and elk, comprising roughly 4,000 adult elk, 4,000 calves, 46,000 adult deer and 46,000 fawns.   

With stable breeding populations, that leaves 8,500 elk and 178,000 deer to die annually: other predators, hunter harvest, poaching, tribal harvest, vehicle collisions, disease, accidents and starvation.  If we have 2,000 cougars, and these assumptions are in the ballpark, cougar predation is responsible for nearly half (48%) of all annual elk mortality and over 1/3 (34%) of all annual deer mortality.   
 

Do you have any references for this data? I'm by no means calling b.s. on any of it.  I know you were a state bio in the past so figured you may have some references for this that I could tap into.  I'm working on a report where info like this would be very beneficial.  Thanks.