Does Antler Size Really Matter To Does?

Occasionally, a scientific paper comes out that really makes you sit back and question the results. In this case, thinking outside the box and coming up with a studydesign really got my attention, because it was genius.

Daniel Morina recently completed his Master of Science degree in the Wildlife Department at Mississippi State University. One part of his thesis dealt with trying to determine exactly what a doe is really looking for in a buck prior to the actual breeding process. In other words, can you independently associate a buck’s body size, age, or antler size with what a doe is looking for in a mate?

Before we look at Morina’s study design, we need to understand that a buck’s antlers serve three main purposes: signal, weapon, and display ornament. One, large antlers are a signal to younger bucks. We know antlers are a reflection of a buck’s age and condition, but large antlers can intimidate smaller bucks and actually save them from potential harm.

Second, antlers can be used as weapons between bucks of similar size. Although fighting to the death is rare, it does occur. And while many hunters assume larger antler size is a benefit when fighting, the strength of the antler itself is actually more important. For example, large antlers that are fragile from a density standpoint and break off, do little in helping a buck establish himself within a herd’s hierarchy. This is one reason why smaller-antlered bucks with strong, high-density antlers win more skirmishes.

Third, antlers act as a display ornament to attract does, especially during the rut. This finding is something many biologists and hunters suspected, but this assumption is something no one could prove. Working at the Mississippi State University Deer Unit, Morina wanted to determine if body size (weight), age, or antler size was more important in mate selection. Or, was there a combination of factors involved? Most hunters would assume a doe would choose a large-antlered, larger-bodied, and older buck. But did this occur, and how can you look at each variable independently?

Morina took all his bucks and cut off their antlers two to three inches above the pedicle. With some redneck engineering, he then used an aluminum coupling device developed by his advisor, Dr. Steve Demarais, that was milled to fit over a buck’s cutoff antler. He attached the coupling device with screws, and then bonded and taped it over the antler base. This made it easier to install and switch any pair of antlers to his various bucks. Using this homemade coupling device, Morina could easily put small antlers on bucks that previously had large antlers, and vice versa.

To determine which buck had the higher preference rate, 25 estrous does were placed in a central enclosure. On both sides of the doe enclosure, a buck was placed in adjoining enclosures. Infrared video cameras were then used to record whether the doe was walking or bedded down within 10 feet of the fence that housed a specific buck. In each 36-hour trial, the doe had the choice of spending her time with the “preferred” buck, which was located on both sides of her enclosure.

The first trial involved a buck’s body weight. While keeping antlers the same size and the ages of all bucks consistent, Morina used bucks that were at least 35-percent different in weight. Although you may assume the does preferred the larger bucks, Morina saw no significant selection preference for one over the other by does.

Within the second trial, Morina used bucks of the same weight and antler size, but at least three years’ difference in age. Once again, there were no significant selection preferences between a doe choosing an older versus a young buck. I don’t know about you, but this really surprised me!

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On the final trial, Morina used bucks that were the same age and no more than eight-percent different in weight. Then he attached large antlers that averaged 163 inches on some bucks, and small antlers (64 inches) on others. Again, measuring the does preferred response to these bucks on each side of her enclosure, Morina found the does walked the fenceline near the larger-antlered buck 80 percent of the time. Additionally, the does bedded 79 percent of the time next to the larger-antlered buck.

I shared Morina’s finding with Bowhunter Contributor and decoy aficionado Danny Farris, and asked him his thoughts on the “bigger is better” antler results. Farris agrees with the results when it applies to doe-buck relations, but reminds hunters that during the hunting season, the social hierarchy among bucks is constantly changing. And this is a completely different matter. If a buck has smaller antlers, it’s a signal to larger bucks that they can easily kick some butt. This is one reason why deer decoys with smaller antlers are so effective, especially during the rut.

Other genetic research has shown smaller-antlered bucks have been reproductively successful in various herds. Morina agrees, but says, “Bucks will always be a primary driver during the rut. But, we’ve shown does also have a role that we are just beginning to understand in an evolutionary time scale.” In conclusion, the does in Morina’s study did not prefer bigger-bodied or older-aged bucks, but they did favor bucks with bigger antlers. So, if you’re wondering, yes, size does matter.

C.J.’s Summary

Although many believe weight and age are important, Morina’s study showed does prefer a buck with larger antlers. Biologists now know antlers simultaneously serve as a weapon between bucks, and a display ornament to attract does.

Biologists know a deer’s body weight seldom drastically changes from one year to the next, but the size of antlers can easily swing one way or the other by 10 percent. Why does this occur? Most likely because body size/weight is essential for survival, whereas antler size is important for reproduction. Research has shown the differences in antler size from same-aged bucks can be a valuable tool in assessing the condition of a deer herd.

For more information on Morina’s research, click here.