The World of Whitetail Antlers Part 2
By: Dr. James C. Kroll
In Part 1 of our antler growth discussion, I discussed how we believe antlers came to be the unique appendages in the deer family, first possibly as scent dispersal or display organs, then later evolving into their primary role as defensive and male combat organs. Whereas antler-like appendages were permanent protuberances from the frontal bones of the skull, modern antlers grow during a certain time of the year (depending on the hemisphere), die and remain attached to the skull for a period of time, then are cast to start the process anew. In this installment, I will discuss how antlers grow, the genetics of antler growth and what can happen during their growth.
Even as very young fawns, bucks begin growing the all-important pedicel from their frontal bones. Development of the pedicel is controlled by testosterone, the primary male sex hormone. Most buck fawns have a well-developed pedicel by 5-7 months. Whitetails are short-day breeders. The amount of hormone produced is determined by length of day.
Oddly enough, the buck measures length of day inversely — by measuring the serum concentration of melatonin produced by the pineal gland in the brain. Since more melatonin is produced at night, the buck’s brain can measure the concentration in the blood to obtain day length. Melatonin also affects another gland (hypothalamus), which consequently influences testosterone production. Another hormone, IGF (insulin-like growth factor), is produced by the liver under the direction of the pituitary gland. Yes, I know this is complicated, but stick with me!
READ THE FULL STORY ON NORTH AMERICAN WHITETAIL