Effects of harvest, culture, and climate on trends in size of horn‐like structures in trophy ungulates

摘要: Hunting remains the cornerstone of North American model wildlife conservation and management. Nevertheless, research has indicated potential for hunting to adversely influence size horn-like structures some ungulates. In polygynous ungulates, mating success males is strongly correlated with body structures; consequently, sexual selection favored development large horns antlers. Horn-like are biologically important great cultural interest, both which highlight need identify long-term trends in those structures, understand underlying mechanisms responsible such trends. We evaluated horn antler trophy (individuals exhibiting exceptionally or antlers) recorded from 1900 2008 Records Big Game, comprised >22,000 records among 25 categories encompassing geographic extent species occupying America. The broad-scale nature data neutralized localized effects climate population dynamics, making it possible detect meaningful changes over past century; however, ages individual specimens were not available, prevented us evaluating age- class specific size. Therefore, we used a weight-of-evidence approach based on differences life-history characteristics, distribution, morphological attributes, harvest regimes discriminate competing hypotheses explaining provide directions future research. These young male age structure caused by intensive (H1), genetic change as result selective (H2), sociological effect (H3), (H4), habitat alteration (H5). Although number entries per decade increased most categories, negative significant 11 17 antlered 3 8 horned categories. Mean predicted declines during 1950-2008 1.87% 0.68% antlers horns, respectively. Our results consistent nutritional limitation imposed (H5) explanations trophies. contrast, our harvest-based explanation. Two that experienced conservative America (i.e., bighorn sheep (Ovis canadensis) bison (Bison bison)) did exhibit significant, trend addition, pronghorn (Antilocapra americana), capable attaining peak 2-3 years age, significantly century. Both support intensive-harvest hypothesis, predicts gradually shifted towards younger, thus smaller, males. absence mountain goats (Oreamnos americanus), difficult accurately judge field, provided selective-harvest hypothesis. One other prediction followed hypothesis was supported; game more susceptible reductions A harvest-induced reduction can increase harvested prior size, whereas may be less likely occur free-ranging populations when factors, nutrition, override Long-term incentive evaluate appropriateness current paradigm, wherein focused largely males; although lack information rigorously differentiating causal mechanisms. Disentangling underpinning daunting task, but one worthy additional elucidating relative nutrition (both demographic genetic) harvest. 2013 Wildlife Society.