Tuesday, March 11, 2014
By Bob Humphrey
Deer hunters pursue their quarry for many reasons but among the top is antlers. We marvel at these natural works of art. Big antlers bring bragging rights at hunting camp, win local contests and get hunters in the record books. But what makes one deer’s antlers bigger than another? Most hunters know antler size is influenced primarily by three things: age, nutrition and genetics. Let’s start with the genetics.
It’s probably fair to say most bucks are born with a genetic predisposition to grow a good set of antlers, though there are exceptions. Some deer don’t have the genes. Sometimes absurdly big racks are produced by captive deer and some free-range deer in lightly hunted areas.
Next comes nutrition. If given enough of the right food, bucks will grow bigger antlers, but limiting factors vary. Antlers are bone, which consists of minerals. Deer get minerals from the soil, indirectly through plants they eat. The soil must contain the right kind of minerals in the right amount. Then there must be enough of the right types of plants to convert those minerals into useable form. And deer need to be able to access those minerals at the right time of year.
Biologists use the average yearling antler beam diameter (YABD) of bucks from a particular area as an index to the population size in relation to habitat. Average YABDs of 15-16 millimeters or less generally indicate the population is exceeding the carrying capacity. The 17-19 mm range indicates deer are near carrying capacity. When average YABD exceeds 20 mm, it’s a good sign deer are below the carrying capacity and there is ample nutrition.
If deer populations are maintained at sufficiently low levels, as in Maine, food is not a limiting factor most of the year. Where it becomes important is in winter. Without sufficient winter food, deer become stressed and it takes them longer to recover from that stress in the spring. This effectively delays antler growth the following year. That’s at least partly why Maine tends to produce fewer trophy-class bucks.
This brings us to the third and arguably most important factor – age. Antlers begin growing from the already-formed pedicels on a buck’s forehead just a few months into his first spring. By autumn they’ll protrude slightly but are usually covered by leathery buttons. It’s not until his second year that a buck grows his first real set of antlers. These yearling bucks typically sport single spikes or forked antlers, but with exceptional nutrition it’s possible to grow a rack with several points. Regardless, this is the age class that experiences the most hunting mortality, which is why most hunters end up with small-racked bucks. If they let them go, they would grow.
The following year is a big one, though not the biggest in terms of antler growth. By age 2 a buck in good habitat should sport a decent rack of six to eight points or more. Again, depending on genetics and nutrition, it may measure somewhere between 110 and 130 inches (occasionally larger), according to standard measurements used by antler scoring organizations. They represent the majority of deer taken by those willing to hold out for a decent rack buck, or lucky enough to have one happen by.
If it manages to reach age 3, a buck should realize noticeable improvement in antler size, possibly scoring as much as 140 to 150 inches, possibly more. These are the majority of Maine bucks that will meet minimums for the Maine Antler and Skull Trophy Club, and end up at the taxidermist. But we’re approaching the peak of the population pyramid. There are far fewer older deer in the annual harvest.
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