Effects of harvest, culture, and climate on trends in size of horn-like structures in trophy ungulates; Los Efectos De La Explotación, La Cultura Y El Clima En El Tamaño De Estructuras Corniformes En Los Ungulados Tipo "Trofeo"; Effets de la récolte, de la culture, et du climat sur les tendances de la taille des ornements chez Les ongulés à trophée

• Published in: Wildlife monographs 2013-02, Vol.183 (1), p.1
• Main Authors: Monteith, Kevin L, Long, Ryan A, Bleich, Vernon C, Heffelfinger, James R, Krausman, Paul R, Bowyer, R Terry
• Format: Article
• Language: English
• Subjects: Body size; Climate effects; Flora; Geographical distribution; Habitats; Harvesting; Life history; Nutrition; Ungulates; Wildlife conservation
• ISSN: 0084-0173; 1938-5455
• DOI: 10.1002/wmon.1007

Hunting remains the cornerstone of the North American model of wildlife conservation and management. Nevertheless, research has indicated the potential for hunting to adversely influence size of horn-like structures of some ungulates. In polygynous ungulates, mating success of males is strongly correlated with body size and size of horn-like structures; consequently, sexual selection has favored the development of large horns and antlers. Horn-like structures are biologically important and are of great cultural interest, both of which highlight the need to identify long-term trends in size of those structures, and understand the underlying mechanisms responsible for such trends. We evaluated trends in horn and antler size of trophy males (individuals exhibiting exceptionally large horns or antlers) recorded from 1900 to 2008 in Records of North American Big Game, which comprised >22,000 records among 25 trophy categories encompassing the geographic extent of species occupying North America. The long-term and broad-scale nature of those data neutralized localized effects of climate and population dynamics, making it possible to detect meaningful changes in size of horn-like structures among trophy males over the past century; however, ages of individual specimens were not available, which prevented us from evaluating age-class specific changes in size. Therefore, we used a weight-of-evidence approach based on differences among trophy categories in life-history characteristics, geographic distribution, morphological attributes, and harvest regimes to discriminate among competing hypotheses for explaining long-term trends in horn and antler size of trophy ungulates, and provide directions for future research. These hypotheses were young male age structure caused by intensive harvest of males (H1), genetic change as a result of selective male harvest (H2), a sociological effect (H3), effects of climate (H4), and habitat alteration (H5). Although the number of entries per decade has increased for most trophy categories, trends in size of horn-like structures were negative and significant for 11 of 17 antlered categories and 3 of 8 horned categories. Mean predicted declines during 1950-2008 were 1.87% and 0.68% for categories of trophy antlers and horns, respectively. Our results were not consistent with a sociological effect (H3), nutritional limitation imposed by climate (H4), or habitat alteration (H5) as potential explanations for long-term trends in size of