A decade-long study on antler progression in mule deer revealed some surprising results — muley bucks reach their antler peak earlier than most hunters thought.
Justin French, Big Game Specialist and Research Scientist at the Borderlands Research Institute at Sul Ross State University, led the research and presented results at Caesar Kleberg Wildlife Research Institute’s Deer Research Meetings in March.
“To study mule deer antler progression, it requires monitoring a large number of known-age bucks,” he said. “And it takes 10 years to get the data, which is tough with free-ranging mule deer, since the density is low and their range is wide.”
Two questions considered in the study were:
When do bucks mature?
Do scores crash later in life?
“Predicting future antler characteristics depends on understanding antler progression,” French said. Researchers captured 93 bucks as fawns or yearlings over four years in the study, then fit them with colored ear tags and numbers. Then they monitored feeding and water stations with game cameras for 10 years.
Using a computer program to estimate antler scores, antler progression curves were developed for 53 bucks. “The scoring system, called ICY, was developed by a student,” French said.
When scores were compared with known physical measurements, a correction factor was applied.
“The estimated scores were coming in a little high,” French said.
Two patterns were discovered.
“The average buck reached a peak score of 152 4/8 by 5.5 years of age,” French said. “That’s younger than often thought for mule deer. I’ve heard most of my life that they hit their peak at age 7 or even 8.”
The bucks were found to hold onto those scores for a good while, though.
“There was little evidence of a crash on average,” French said. “They reach their peak earlier, but hold on to the peak longer.”
As might be expected, there was a lot of variation in the individual results.
“Some bucks peaked at 3 and fell off,” French said. “There was about a 20-percent variation with how early or late they peak.”
French said some of the conceptions of when mule deer peak could be a result of the difficulty of aging mule deer on the hoof.
“It could be we were aging wrong all along on the hoof,” he said. “We used mule deer biologists and showed images of bucks and gave them 30 seconds to estimate age. They were only correct one out of four times. There was a tendency to age to the middle.”
French said the study was the first of its kind in the Trans-Pecos.
“Levi Heffelfinger at CKWRI did some research in the Panhandle with similar results,” he said.
Selective harvest also was examined in the study.
“Culling really doesn’t work to improve antler quality in mule deer,” French said.
What should wildlife managers do?
“You can manage to the habitat and nutrition,” French said. “If you don’t like a certain buck and if there are good numbers, take it and leave more resources for the rest of them. At the least, selective harvest increases access to resources for the bucks you like.”
Photo from Boarder Land Research
