Well, I have read the paper referenced by SG and it really doesn't shed much more light than is in the abstract. It raises serious questions about the validity of young ram survival numbers based on skull counts and gives several postulations of why the method would be so innacurate on that count. It draws no conclusions but seems biased to the end that high mortality of young rams is from vulnerability to environment conditions rather than decreased vigor from increased reproduction effort caused by an unsound harvest regime.
The other thing that is interesting was this quote "Survival varied among years if hunting mortalities were ignored, but not when all causes of death were considered." Which they make no futher comment on, but I interpret to be - Basically, when less legal rams were killed by hunters, more died from natural causes maintaining a stable death rate. This is very consistent with managed harvest theory.
The other thing to note is that the total annual death rate of mature aged rams in this hunted population mirrors the death loss numbers from studies on non-hunted populations in other studies such as the one conducted by Geist. The only discrepancy in the data from this study and others (regardless of whether the study is in a hunted or non-hunted population) is in the <2 year category where skull count studies have matching low loss rates and marked animal studies have consistent high loss rates. Personally I would place much greater stock in the numbers coming from the marked animal studies, but as the authors lament, published studies of marked ungulates are rare.
After reading this study I have serious doubts that a change in the harvest strategy would actually result in a greater number of older rams on the mountains, unless it is true that a reduced harvest of rams in the 5-7 year class would result in a decreased mortalility of the <2 year rams. If such were true then there would be an increase in older rams on the mountain as a result of the overall increase of the number of rams in total. As I said though, the authors raise a lot of questions that are as yet unanswered regarding the validity of such a theory.
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