Do Dry Years Grow Bigger Bucks?

The original question asked of Macy Ledbetter, wildlife biologist as a multi-part question that is paraphrased as follows:  In drought years, are deer forced to eat food sources that are better for them in terms of antler development? And, what impact does supplemental protein feeding have in drought years on antler development? The essence of the question quickly became “Do Dry Years Grow Bigger Bucks?” Here is Macy’s response.
There is some research from South Texas that shows that during drought times, and when deer are eating more protein pellets, that they do in fact eat less browse plants.  Put simply:  deer have to eat every day, just like us. The problem is however, that the native habitat can only produce X amount of volume of browseable forage (within a deer’s normal reach) at any given time.  So, if it rains and the plants are actively growing (plants include forbs, grass, weeds, flowers, brush and trees in this writing) they can produce MORE food than the deer can consume. Basically, the supply is greater than the demand.  In this situation, deer eat LESS protein pellets because they don’t need it.
Another thing to remember is that most deer PREFER NOT to eat at feeders but do in fact prefer native vegetation over manufactured feed.  So when Mother Nature sets the table and the table is full of forage (lots of rain equals lots of plant growth) you will notice your pelleted feed consumption drops dramatically.  The recent case in point is when the mesquite beans ripened last month in south Texas (July).  Did you notice the dip in the feed consumption when this happened?  Most folks did, especially those writing the check each month!
Now, turn the table the opposite way.  If deer have to eat every day and they prefer to eat native plants, what do they do when it quits raining and there is NOTHING to eat?  Of course their stomach overrides their preferences and they readily accept any and all manufactured feeds.  This is why is it called “supplemental” feeding and not “primary” feeding.  The idea of offering a deer a manufactured feed in the form of a protein pellet is to give him options when he has none.
So, when times get hard and things turn dry, the deer will step up their daily pellet consumption because they HAVE to, not because they WANT to.  By the deer accepting this feed, their bodies will not go through the nutritional “feast or famine” and will stay on a more even nutritional plane (or level) and this is good for rumen health and normal body functions and that translates into healthier fawns, more fawns and bigger antlers.
For those of you just beginning a supplemental feeding program, the very first thing you will notice the first fall after the initiation is improved body weights.  NOT bigger antlers, but improved field dressed body weights.  Healthy deer are bigger, fatter and heavier.  The second thing you will notice is that your fawn survival rates will increase dramatically the following spring.  This is simply a function of mother’s health.  Now her body is healthy and she can give not only quality milk, but quantity of milk and it is usually enough to support BOTH fawns instead of just one.  So, healthy deer are heavier and because the females are able to produce more and better milk, her offspring are more likely to survive.
The third and final thing you will notice is larger antlers in the YOUNGER age classes.  Remember, antlers are a by-product of health.  A bigger healthier animal that got a good start at life can grow quicker and better.  Because antlers are made up of “left over” nutrition, the younger bucks have more of this left over nutrition sooner in life, and so for their ages, they can produce larger racks.   This third phase of observation usually happens on the third year while the first two happen in years one and two.  So, it takes supplemental feeding three full years before you can honestly see benefits from improved antler production.Now, back to a minor variant of the original question, which is Will dry years grow big bucks?  The answer is Yes!  So, how and why is that possible?Never forget the bell shaped curve of genetics.  That means that 25% of any population is “below average” and will always be below average.  Half (50%) of the population will be “average” and will always be average; however, average is a relative term for the population.  The other 25% of the population will be “above average” and some of these animals will be GREAT.
Within the 50% “average population”, in bad years you will have deer than can decline and will fall into the “below average” category. Conversely in good years, you will have deer normally considered to be average that can improve just enough to be considered “above average”, or even very good.So let’s say it rains perfectly and every deer has more than enough to eat.  In this case, supply far outweighs demand.  In this situation there will still be below averagedeer, or “sorry” deer, because their genetics are holding them back.  They will be big, fat, healthy and sorry.  In this ‘wet’ year, the “average” bucks will be better now (remember that average is a relative term) so the average of the herd is now improved because of the improved habitat conditions.
And in this same wet year, there will be a small percentage of “average” bucks that will slide over into the “above average” category. We call these deer “swing deer”.  They can swing into the above average category in good years. Their genetics are pretty good, but nutrition in less than great years has been holding them back.  Now, the good genetics are going to show up in the form of larger antlers because their full genetic potential is realized.  They lack for nothing, they need nothing and they grow a bigger rack because of that.
So, on wet years, big deer appear everywhere. This is due to two reasons. First, you have the swing deer showing up in big numbers. And secondly, the top 25% of the bucks that are already above average literally explode antlers on their head.  The average deer become good and the above average deer become great because the nutrition allowed it.Now, let’s assume a drought hits … like it has in Texas and the entire southwest this year.  Those below average deer ( or sorry deer) will remain sorry because that is the best they can do.  Sorry is as sorry does.  The average deer will dip downward because now the average is relative and so the entire population standards decline, but they are still average.  Those swing deer in the average herd revert back into only the average and do not move into the upper good class but instead, fall back into only the average classification (which is still relative).  The great deer are still great but simply not as great.  The nutrition did impact them for sure but their genetics allowed them to push through.  So, they grow big antlers but they are still down somewhat in terms of their potential.This is why there will still be some very large deer taken this fall.  There will not be nearly as many total big deer as last year, but there will still be some big deer taken.  I think you will see the field dressed body weights and fawn survival rates way, way down from last year.  Antlers are by-products of nutrition and when nutrition is lacking, antlers and those that are average will suffer the most.
I seriously doubt you will see a new world record typical buck, or a new Texas state non-typical record set like you did last fall … which this site was the FIRST to announce both bucks!  And I also doubt that the deer contests will run out of deer contest jackets or prizes like they did last year.
Here is a link to the authors site and to the source of this article.
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