Meagan Koster heard the tree branches break as the bull elk moved closer. He grunted, then stopped broadside in front of the 17-year-old Koster. She pulled the trigger on her crossbow.
The elk moved 15 yards before collapsing.
She knew the elk she shot Sept. 21 was big, but she didn’t know how big. Measuring more than 377 inches, it set the new Safari Club International world record for a North American elk shot with a crossbow.
Antler sizes on the biggest Rocky Mountain elk haven’t changed much during the past century. It’s as easy now — or hard, depending how you look at it — to shoot a record elk like Koster’s as it was in the early 1900s. But, recent research shows, for some species, average sizes of the biggest animals are shrinking.
Average horn and antler sizes of more than 14 trophy categories of mammals in North America have decreased in the past century, according to research in a paper entitled “Effects of harvest, culture, and climate on trends in size of horn-like structures in trophy ungulates” published in February in Wildlife Monographs.
The decrease could be due to hunting pressure on males, according to the paper. It was written by a team of researchers from Idaho State University, wildlife biologists from Arizona and California game and fish departments and the Boone and Crockett Club professor at the University of Montana.
By analyzing the Boone and Crockett Club’s comprehensive record data, the scientists wanted to see if horn and antler size had changed over time, said Kevin Monteith, a researcher at the University of Wyoming, who was finishing his Ph.D. If it had changed, they wanted to know why.
“There is this rigorous, long-term data set that’s been acquired and collected and no one has really looked at it,” Monteith said.
Theodore Roosevelt started the Boone and Crockett Club in 1887 in response to disappearing big game species, such as bison and pronghorn, said Paul Krausman, a co-author and the Boone and Crockett Professor at the University of Montana.
The club formed to help bring large mammals back. Its members were instrumental in forming national parks like Yellowstone and Yosemite.
At the same time, it became a keeper of records.
“That’s where the whack ‘em and stack ‘em part came in,” Krausman said.
Each North American ungulate, or hooved mammal, has a minimum horn or antler size it must meet to be submitted into the record books. The data represent only the largest trophies.
What the researchers found surprised them. From 1950 to 2008, antler sizes of 11 of the 17 trophy animal categories decreased by
1.87 percent. Average horn sizes in three of the eight animal categories decreased by 0.68 percent, he said.
“The reality is they were negative and statistically significant,” Monteith said. “But if you look at it across the board it is less than 2 percent in antler size. That’s very little.”
The researchers looked at all possible variables including climate change and an increase in entries. An increase in hunting of males was the only consistent factor, Monteith said.
As animals such as deer and moose age, their antlers grow. If more males are killed before they reach their peak antler size, average trophy size could decline, Monteith said.
Of Wyoming’s species, researchers found decreases in Shiras moose, mule deer and white-tailed deer. Rocky Mountain elk, bighorn sheep and mountain goats stayed the same. Pronghorn actually increased.
What the data means for management is up to each state, Monteith said.
Whether or not states should change hunting regulations, “really depends upon the way in which you place your values or if they deem a change is even necessary,” Monteith said.
Troy Koster, the Cody hunter whose daughter set a new elk record, believes large, quality bulls are still available. But no matter what species, the biggest ones are few and far between.