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UM News
February 08, 2013


The size of antlers and horns in 25 trophy categories of big game in North America have declined over the past 108 years, according to data analyzed by a team of scientists including UM Boone and Crockett Professor of Wildlife Conservation Paul Krausman.

Six researchers studied data from 22,000 Boone and Crockett Club records. They found a small, yet consistent 2 percent decline in horn and antler size. The results of their study, “Effects of Harvest, Culture and Climate on Trends in Size of Horn-Like Structures in Trophy Ungulates,” were published in the January issue of Wildlife Monographs, a publication of The Wildlife Society.

“The Boone and Crockett Club is the oldest conservation club in the U.S. and the second-oldest in the world,” Krausman said. “One of the things the club does is maintain a record of all the horns and antlers of species in North America. They use it as a record of the health of wild populations, but it had never been analyzed.”

Evidence moderately supports that an over-harvest of males – which would lower the age structure – allows fewer animals to reach trophy status prior to harvest. The evidence also provides limited support for genetic changes from selective harvest of larger males.

“All of the authors hunt, and initially were quite surprised by the outcomes from their research,” said Idaho State University biological sciences Professor Terry Bowyer, who oversaw the initial analyses at ISU. “No other study, however, has spanned the time, geographic extent, simultaneously examined multiple ungulates – big game species – or amassed such a huge sample size.”

The article outlines management recommendations to overcome the decline and to address potential causes of smaller horns and antlers. It also notes, however, that the reduction in size of trophy horns and antlers is small. The recreational, management and conservation benefits from hunting may offset the detriments of a small reduction in trophy size.

“It’s statistically significant; it’s really a change,” Krausman said. “But biologically it doesn’t make a whole lot of difference.”

The authors include Krausman, Kevin Monteith from the University of Wyoming; Bowyer and Ryan Long from ISU; Vernon Bleich with the Sierra Nevada Bighorn Sheep Recovery Program of the California Department of Fish and Game; James Heffelfinger with the Arizona Game and Fish Department.

For more information call Krausman at 406-241-1489 or email



State, National Wildlife Biology


Contact: Paul Krausman, UM Boone and Crockett professor of wildlife conservation, 406-241-1489,