QUESTION: Hi Bob, in order to monitor which deer survived our hunting season, I placed corn in front of my trail cam and was surprised to capture this photo of two bucks fighting. This raises an interesting question. Will bucks fight at times other than the rut or when they are competing for does? - Wes
ANSWER: Bucks have aggressive interactions for several reasons. In early fall, waning day length triggers an increase in testosterone. This in turn causes bucks to become more aggressive.
They start by taking out aggression on the local vegetation, and eventually on one another. Casual sparring and shoving matches become more intense, as do posturing, snort-wheezing and other forms of intimidation. This "pre-season training" period is a way for bucks to get in shape for the breeding season. It also helps them establish a dominance hierarchy - a pecking order.
Sorting out the hierarchy before the rut has the distinct advantage of minimizing the likelihood of real combat.
Occasionally, two evenly-matched bucks square off over breeding rights and the results can be quite dramatic.
As with any animal behavior, there's a cost-to-benefit ratio associated with fighting.
The benefit of winning a fight could mean the right to mate with a particular doe and pass along genetic material to the next generation.
The cost of participating in one is, at the very least, a loss of energy, which becomes increasingly important going into the stress of winter.
Even greater costs include injuries that might take weeks or even months to recover from, or the ultimate sacrifice, death.
All the above are reasons why fighting is usually a last resort and fairly rare occurrence which is typically restricted to the peak breeding period.
As noted, bucks will spar before this, sometimes quite aggressively.
After the rut, the incidence of fighting declines fairly soon. Again, this is because of the energy cost at a time when bucks are depleted and food is becoming scarce.
However, the second rut might spur a slight increase in aggressive behavior. Additionally, some bucks might lock "horns" and engage in a little shoving match for reasons we don't clearly understand.
The bucks in your photo don't appear to be highly aggressive, and this interaction could simply be some sort of post-rut greeting, somewhat analogous to hockey teams shaking hands after a hard-fought game.