Populations with "young" age structures are growing populations, for the most part, if the sex ratio is not too badly skewed one way or the other . Populations with an "old" age structure may be stable (in the absence of significant predation and with recruitment equaling mortality), or declining (i.e., recruitment is less than mortality).
I am not familiar with the data from Banff that Casey cited, but I cannot remember having seen cervid populations with sex ratios greater than 1:2 (males to females) that were not intensively managed to achieve these levels. That includes a lot of unhunted populations around the globe. All of the life table data that I have reviewed indicates that males naturally suffer higher mortality rates than females at all ages, but especially in the first 2 years of life.
I would be interested to see some population data for free-ranging elk herds with naturally high male/female sex ratios in the absence of hunting...
