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Discussion Starter · #1 ·
Went for a short "Sunday drive" and found a few deer. One fawn was with a doe and looks to be extremely small for this time of year. Also found a couple a bucks hanging around town. Not a bad quick trip.
 

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That's the age old argument right? The theory that a lack of mature bucks means does wont let themselves get bred by smaller bucks early on in the rut, but they may later when they come back into heat in December. Pushing back the pregnancy date until the Dec estrous means a month later birth which means a fawn with a month or more less growth come winter. Means fewer fawns making it through winter.


-DallanC
 

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Discussion Starter · #3 ·
Obviously part of life, but you can't help but feel bad knowing, or thinking we know, it won't make it through the winter.
 

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That's the age old argument right? The theory that a lack of mature bucks means does wont let themselves get bred by smaller bucks early on in the rut, but they may later when they come back into heat in December. Pushing back the pregnancy date until the Dec estrous means a month later birth which means a fawn with a month or more less growth come winter. Means fewer fawns making it through winter.

-DallanC
And the problem with that theory, is that breeding later in the first estrous cycle, or breeding in the second estrous cycle, creates more bucks, and hence higher buck to doe ratios.

So with higher buck to doe ratios like we currently have, statistically there are also more mature bucks as well, which puts a big hole in said theory.

The problem is one of synchronous estrous cycles, which should be brought on by shortening days in healthy does. When the does are ready, they are ready, spike or 30" wide 4 point. It is a matter of overall health of the does, not a matter of whether there are mature bucks. Ultimately if everything is working as it should, you should have most does coming into estrous around the same time. This is turn brings on the rut which drives fighting among bucks for breeding.

There are several reasons why this is important. First is that mostly healthy does will be going into estrous, which helps assure the best chance for survival. The synchronicity of the rut, which is brought on by the synchronicity of healthy does going into estrous, ensures that fawns are all born to healthy mothers at around the same time. This ensures survival by saturating areas with fawns, which reduces the impact of early predation. This also keeps the at birth sex ratio at ~50:50 which among healthy populations shifts over time to ~10-20:100. These ratios among healthy deer with synchronous ruts are what are required to propel the trend line in an upward fashion. With regard to rutting bucks, there is some evolutionary genetics going on. With mature bucks challenging each other in the rut, it ensures that healthy, tested, bucks are doing the breeding.

So what happens when things don't play out under these ideal conditions? Lets say for example that something messes with the hormones of deer, which leads to metabolic disorders such as hypothyroidism(Which has been documented in deer all over the West).

So the first generation of deer that face this, may have minor problems. For example some does may not go into estrous in November. And some bucks may wonder around looking for little blue pills instead of going into the rut. The results of this are that the fawns born the next year are spread out, which drives higher predation rates among the fawns, later into the year. Also because of breeding occurring during the second estrous cycle, the at birth sex ratio is skewed in favor of males, which also drive mortality, because you lose male fawns at a higher rate than females. The remaining fawns have now inherited their parents health problems, with many females being born with congenital hypothyroidism, and are affected by this more than males by a ratio of 3:1. On the other side some males are born with malformed genitalia because of the affects of their mothers metabolic disorders. This is because the thyroid drives the genetic programming of many fetal developments including sexual dymorphism.

So as this progresses over a few generations, and the problem is fed with more hormonal disruption, the affects become more defined, and more extreme. With fawns being born at different times you now have more than one factor that is affecting the synchronicity of does going into estrus. The fawns that were born later in the year will also go into estrous later compounding the problem. Buck to doe ratios increase, fawn to doe ratios decrease, everything becomes more de-syncronized, and overall health continues to decline. Inevitably under these conditions(these are current conditions in many places by the way) the population heads into a slow unmarked decline, or suffers a massive quick decline because of a heavy winter or other exacerbating event, followed by slow to no recovery like we saw after the major decline of the early 1990s.

Real world example: I was watching 15 deer this evening, 12 does and 3 bucks. Of the 3 bucks one was a standard 4 point, one was a decent 2 point, and one was a small 1x2. Of the does 2 were being pursued by a buck because they were obviously in estrous. So which buck do you think was doing the pursuing? Guess what? it wasn't the 4 point. The 2 point was working the does and keeping very close tabs on the 2 does. The 1x2 stayed well away from all the activity, as did the 4 point. I almost did not see the 4 point at tree line he was so far removed. Shirker? Queer? I don't know, but what I do know is that is not normal, that is not how it is supposed to work.

While I can not confirm any of the above mentioned health problems in these live deer I watched. I have observed all of the before mentioned in road kill deer within a few hundred yards of where this was playing out.

So....just what are the ramifications of that young fawn?.......
 

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You'll never know unless you tie a red ribbon around its neck and watch it until next summer.
 

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An urban deer like that probably has decent odds of survival compared to a fawn out in the sage brush...
True, but I see a few small ones like this dead along my commute road every couple of days. Being that small they just go where mama goes, she at least might look for a car before running across... fawn just runs after mama and gets hit.

-DallanC
 

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And the problem with that theory, is that breeding later in the first estrous cycle, or breeding in the second estrous cycle, creates more bucks, and hence higher buck to doe ratios.
i'm curious on the science behind this? is it a widely accepted wives tale or just something to do with deer X's and Y's that i don't understand. It certainly doesn't work that way in people.

edit: nevermind, i should read thoroughly instead of skimming. you explained it clearly.
 

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i'm curious on the science behind this? is it a widely accepted wives tale or just something to do with deer X's and Y's that i don't understand. It certainly doesn't work that way in people.

edit: nevermind, i should read thoroughly instead of skimming. you explained it clearly.
More specifically, is the chemistry that I did not mention. It has to do with acidity. Biochemically, later in the estrous cycle does becomes more acidic, which favors male sperm over female sperm. This applies even more so to the second estrous.

Another part of this would be metabolic acidosis induced by "hormone disrupting agents", like those that cause thyroid disruption. In the case of metabolic acidosis, male sperm would be favored over female sperm even early in the first estrous cycle. And if does are not at peak health, an active, or overly active immune response would also have the same affect. The immune system of a sick doe would respond to sperm by creating a more acidic environment, which male sperm can more easily overcome.

You see copper and other mineral deficiencies in association with metabolic disorders such as metabolic acidosis. It messes with a lot of things.
 
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