Mike Belt said:
OK let's take a potential scenario. We'll say that there's a sizable property with a pre-hunt adult sex ratio that is adequate. During hunting season a big percentae of the bucks are killed and not many does and this happens for several seasons in a row. Buck fawn recruitment is going to rebalance that sex ratio each summer?
Yes, simply by shear number. Each year, the fawn crop is the largest single age-class of all deer. And approximately half (or a little more than half) of that huge age-class is male. In summer, they turn one year old and become adult bucks at the same time that the next huge crop of fawns (next years adult bucks) are being born. It sounds crazy, but I can show you the math that even if every living adult buck is killed every year, and not a single doe is ever killed, the button buck crop turning a year old and joining the adult population will never allow the
pre-hunt sex ratio to ever be worse than about 3 adult does per adult buck. And in the "real-world" it's far more balanced than that. However, the key to this situation is large fawn crops. If fawn production or survival fawns dramatically, there is no large button buck crop to turn one year old and join the adult population, and in that scenario, pre-hunt adult sex ratios
can become skewed (if a huge difference in mortality exists between adult males and females).
Here's an ultra-simplified version of the math:
Since healthy adult does produce a fawn recruitment of between 80-120% (for every 100 does, 80-120
surviving fawns are produced). Let's say at the end of a hunting season we have 100 adult does, their 100 surviving fawns, and zero adult bucks. And for simplicity's sake, let's say half the fawns are male and half female (50 female fawns and 50 male fawns [button bucks]). Now, at the beginning of the next hunting season, the 50 button bucks have passed their first birthdays andare now 50 yearling bucks [adult bucks]). The 100 adult does from the previous year, plus the 50 female fawns which have now reached adulthood [have passed their first birthdays and are now adult deer]), add up to 150 adult does. So you have 150 adult females and 50 adult males. That's a pre-hunt adult sex ratio of 3 does per buck. And again, that's taking things to the absolute extremes, where no bucks survive hunting season and all does survive hunting season.
You can carry out that simple math of all bucks die and no does die year after year, and the pre-hunt sex ratio stays around 3 does per buck. The growing size of the adult doe population keeps producing even larger fawn crops (half of which are male) that keep replacing the adult buck population each year after those male fawns turn one year old in summer and become adult bucks. of course, in this scenario, the buck age structure is
terrible. The adult buck population each year is 100% yearling bucks.
