108 years’ worth of data on the size of horns and antlers

[mike rossi]

A team of scientists has just completed a comprehensive analysis of 108 years’ worth of data on the size of horns and antlers among 25 trophy categories in North America and discovered that, over the past century, size of trophy horns and antlers for most species has declined slightly.

The team of six biologists—from Idaho State University, the University of Montana, the Arizona Game and Fish Department, and the California Department of Fish and Game, led by Dr. Kevin L. Monteith, now at the University of Wyoming—analyzed 22,000 records of trophy categories of big game from North America, including mule deer, mountain sheep, and moose. Publishing their results in The Wildlife Society’s newest Wildlife Monographs, the authors found a small (less than 2 percent) but consistent decline in horn and antler size across most trophy categories over the past century.

Through careful analyses, the biologists ruled out several potential causes of the declines, including climate change, habitat alterations, and the “sociological effect” of increased interest among hunters in submitting trophies to the record books. Instead, the analyses provided moderate support for intensive harvest of males as the most likely explanation for the declines, which lowers male age structure, allowing fewer animals to reach trophy status prior to harvest.

The findings have potential implications for management of many species, although the small declines in size of trophy horns and antlers may be of little importance relative to the benefits of hunting as the cornerstone of wildlife management in North America. Nevertheless, the authors offer several recommendations to managers concerned about balancing overall opportunity to hunt with opportunity to harvest large males.

The authors were “initially quite surprised” by the results, says Terry Bowyer, who oversaw the analyses at Idaho State University. Yet he adds that no other study has spanned the time (108 years), geographic extent (all of North America), and range of ungulate species (25 trophy categories), or amassed such a huge sample size (22,000 animals), using precise official horn and antler measures of the Boone and Crockett Club. “There is little doubt that our findings are real,” he concludes. “We hope our research will be of value to fish and game agencies charged with the management of these important natural resources.”