Cooperative Fish and Wildlife Research Units Program: Wyoming
Education, Research and Technical Assistance for Managing Our Natural Resources

Wyoming Project

Harvest Records: implications for understanding factors affecting horn and antler size in ungulates

November 2014 - June 2019


Participating Agencies

  • Wild Sheep Foundation - CA Chapter
  • State of Utah, Department of Natural Resources
  • Wild Sheep Foundation - WY
  • Wild Sheep Foundation - National
  • Wild Sheep Foundation - Alberta
  • Wild Sheep Foundation - Arizona
  • Wyoming Community Foundation
Bighorn Sheep

Our overall goal is to provide a rigorous evaluation of two sources of harvest data to document long-term trends in horn size and age of bighorn sheep (Ovis canadensis), Dall’s sheep (Ovis dalli dalli and O. d. kenaiensis), and Stone’s sheep (Ovis dalli stonei) at a regional level, and to quantify the general relevance of trophy records recorded by conservation organizations. For the first analysis, we will seek to collaborate with state and provincial agencies throughout western North America to evaluate records for bighorn and thinhorn sheep collected by biologists. All harvested bighorn and thinhorn sheep are required to be inspected and have their horns permanently marked with a small identification plug. Because those ungulates can be aged via horn annuli, most western agencies employ a program to record size and age of all harvested sheep. Agency harvest records for sheep represent a valuable resource to assess trends in size and factors responsible for those patterns on a more regional basis, and thus, to also provide a more robust test of hypotheses and effects of specific management practices. For our second analysis, our data source will include trophy specimens recorded in the Pope and Young Records Program, which includes nearly all native, North American ungulates. Similar to the Boone and Crockett Club, the Pope and Young Club (founded as a nonprofit organization in 1961) adopted the same, universally accepted scoring system for collecting and recording information on horn and antler size of trophy big game harvested with archery equipment in North America. Minimum entry requirements for the Pope and Young Club however, are markedly lower than Boone and Crockett minimum scores. Therefore, data from the Pope and Young Records Program contain males of smaller size, and thus younger age classes, and the sample size is more than double that recorded by the Boone and Crockett Club.