Got Testosterone? An Overview of Cactus Bucks

This January I was sitting alongside a Sonora saguaro scanning some desert canyons for rutting muleys. The region holds a good number of mature bucks, but unfortunately there is a blemish in their genes and finding a good, deep-forked four-point can be tricky. However, I don’t dwell on this minor flaw; these desert bucks possess unique antler characteristics, heavy mass and abnormal points. This one particular morning I knew I had found something extraordinary. A solid three-point buck, well beyond his prime, was approaching a group of deer. With his nose on the ground like a bloodhound, the ol’ rutting buck looked spellbound. I steadied my tripod, knowing that at any moment the monarch of this small herd would come into view and rightfully teach the intruder a quick lesson. A new buck moved out from within the herd, feeding eagerly as he ignored the trespasser’s presence. This buck’s burrs were exceptionally heavy, velvet-covered, and resembled a cholla cactus, a typical large two-point frame with a handful of two to four-inch points. “Nick,” I whispered, pulling a cactus spine from my ankle, “I found a good one.” Nick, an Arizonan native, has spent countless hours looking for big bucks in the area. After I pointed the buck’s location, Nick quickly shared with me that I had found a local legend named “Ghost.” Nick had never personally seen this buck before, but had heard many a story about him from other hunters.

Ghost was a “cactus” buck. He was not interested in breeding. His behavior and physique were doe-like, unlike the engorged buck who watched Ghost – puzzled at his passive reaction to his rude intrusion on his herd. It was comical to watch the rutting buck nervously looking behind at Ghost each time he would attempt to mount a doe. Ghost never lifted his head from the succulent forbs that covered the desert canyon. Later that morning, I got within 48 yards from Ghost with my bow drawn back, but I was never presented with a good shot.

What is a “cactus” buck? Every year, we see pictures of deer that have bizarre, velvet-covered antlers that have a mass of knobby points and abnormally heavy bases. These are the type of deer usually known as cactus bucks. There has been a great deal of research done on what causes a deer to grow such an uncontrollable glob of velvet and I believe you’ll find the results interesting.

Velvet is an extension of skin that covers the growing antlers. Throughout the growing period, blood carries nutrients to the antlers via the velvet. Mineralization of antlers and a decrease of blood supply due to rising testosterone levels trigger velvet shedding. Testosterone is the hormone that dominates antler growth. In several studies, testosterone was artificially injected into deer during the antler-growing stage. The bucks reacted to the testosterone by shedding the velvet from the antlers before the blood supply had stopped. Have you ever noticed the last bucks to shed their velvet are the yearling bucks and the regressed old-aged bucks? Now you know why, they produce less testosterone than bucks in their prime.

So what do testosterone levels have to do with cactus bucks? Well, everything. In most cactus buck documentations, a buck had the misfortune to turn “himself” into an “it.” The buck’s testes, the major testosterone producer, may have been left on a barbwire fence line or seriously injured in any number of ways. These castrations continuously result in “cactus” formation antlers with permanent velvet.

The effect of castration on antler development varies, depending on the age class of the deer and the stage of antler growth when the castration occurs. If a young fawn is castrated within the first few months, that deer will not develop pedicles and therefore never develop antlers. Older fawns that have been castrated have been documented of growing a permanent, small, knob-like mass of velvet. If an adult buck is castrated during antler growth and in the velvet, the lack of testosterone allows the velvet antlers to continue growing, omitting the velvet shedding stage and total ossification of antler. These antlers may go on growing for a long period of time creating large cactus racks. These antlers will not shed in the spring. However, it has been reported that in freezing climates the moisture enveloped inside these velvet-covered antlers freezes and parts of the antlers break off. I believe this is why we see so many large cactus bucks in mild weather areas. The antlers are able to continue growing and growing without breaking. Arizona, Southern Utah, and New Mexico are prime examples of mild winter range country and large cactus bucks. A buck with fully-developed, hard antlers that is castrated will shed his antlers soon after the occurrence. With little or no testosterone, the buck takes part in the same shed antler cycle as an intact buck but in a quicker period of time. The low testosterone levels retard protein transfer and assists in erosion between the antler and pedicel. The castrated buck’s antlers will drop within a few weeks. The following year the buck may produce another set of antlers that will remain velvet-covered and permanent. It has been reported in Columbian blacktails, that old-aged bucks that were castrated shed their antlers and never developed another set of antlers.

Many deer are thought to be cactus bucks until closer examination. The unique cactus feature can also be found on another strange deer phenomenon. The potential for antler development may also occur in female deer. Many of these females are still fertile and have been observed lactating with offspring. The antlers are formed by short-term increases of growth hormones. Usually these antlered females cannot produce testosterone to complete the antler cycle, as a result, the antlers remain soft and often permanent, similar to a cactus buck’s antlers. It doesn’t take much to put some antlers on a female’s head, one minuscule dose of testosterone is sufficient to stimulate the growth of a pedicle. Other female deer have grown antlers if their ovarian functions are chemically disabled. Have you ever had a run in with an antlered doe? Biologists know little about deer that are afflicted with this condition.

It’s only been a month since I stumbled across Ghost but it feels like a year. Now, I crawl slowly across the urban congestion performing my everyday jobs. During my commute from the driver’s window, if the evening rays strike the slopes just right, I can see Ghost’s haunt. I imagine he is still hanging in the shadows with the does. All the other bucks are thin, hungry, and wounded from fierce battles. Not Ghost, his physique is healthy and energized. December I’ll be back on my rocky perch with high anticipation that ghost is still alive and well, with an even more impressive collection of mass and points.