Hope the gentleman Mr. Roe doesn't mind, but I saved the following great anology from last year since it's an anual topic.
Posted by Certified Wildlife Biologist Chris Roe:
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There is actually a lot of science out there on this. ...I could RE-write a book on this, but in brief:
Antler growth and "drop" is related to testosterone levels in the body, and THAT is related to the amount of daylight vs. darkness AND breeding activity. Those that say that animals can/do drop antlers within a couple of days the same time each year are seeing this fact in action; cycles of day vs. night are consistent year to year, and thus the primary driver of testosterone levels, and thus cycles of antler development. Also, most deer/elk farms/research facilities/populations have fairly stable sex ratios so breeding activity and "intensity" is often fairly consistent year in and year out (excluding changes in age and dominance of course) meaning that breeding affects are fairly consistent.
How does breeding fit in? It depends on age and sex ratios of the population. Animals don't "use up" their testosterone, but testosterone levels can be affected by external stimuli. So - in populations where males nearly equal females, all females typically get bred within their very first estrous cycle. Because of that, "breeding stimulus" (i.e. the scent and pheromones of estrous females) comes and goes fairly quickly - females come in to estrous, they get bred, and that's it. Without external stimulus to keep testosterone high, levels settle back fairly quickly and follow circadian rhythms (day vs. dark). Because the animal's body "metabolizes" hormones "out" of its system at pretty much a fixed rate, the sooner testosterone drops after breeding, the sooner the animal's testosterone levels fall enough to allow the next cycle to begin and drop his antlers.
In populations where there a lot more females than males, then some females miss getting bred the first go-round, and come into estrous a second or even third time. The longer females stay in estrous, the longer males have external stimuli keeping their testosterone levels high. The longer they are high, the longer they - ultimately - keep their antlers (within reason).
Age plays into it as well. Younger males are like teenage boys, with hormones raging; they can stay "stimulated" and excited to breed longer than mature animals. Mature animals know what the "actual" breeding cycle is, and breeding "realities" are, and can - depending on the animal, and - for lack of a better way of putting it - "bow out" of the breeding excitement as soon as females aren't receptive any more. ...young males can keep trying, and thus their testosterone levels might not fall as rapidly as more mature animals. Hence, in these type of populations, mature animals can drop before immature animals.
Antler size and weight also plays in on the equation, but not - in my opinion - significantly.
Body condition plays into it as well. If the winter puts the animal in a net "negative" body condition, then the animal will need to get its body condition into a net "positive" condition before any significant (if any) antler growth occurs. If an animal isn't placed in a net "negative" body condition over the winter (or if the negative condition is very brief), and body condition stays in the "positive" territory, then antler growth can start as soon as hormone levels allow. Hence why food plots in northern areas can help with antler development, and why winter severity/annual moisture can have an impact from year to year.
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Topic: Bucks shedding already (Read 391 times)
