Some Morphological Characteristics of the Crab Orchard Deer Herd

Abstract

Whole and dressed body weights were obtained from 1,009 white-tailed deer (Odocoileus virginianus) from Crab Orchard National Wildlife Refuge, Williamson County, Illinois. Chest girths, hindfoot lengths, lower mandible lengths, and antler dimensions were taken from somewhat smaller samples. The data were analyzed by sex and age, and relationships with body weight were established. Males generally were larger than like-aged females with respect to all measurements. Both sexes reached near-maximum size at 4.5 years of age but females matured earlier than males, especially with regard to body weight. Indices of condition (body weight and antler size) indicated that the previously unharvested Crab Orchard herd compared favorably with nearby hunted populations with the possible exception of yearling males. J. WILDL. MANAGE. 39(1):48-58 This paper describes certain morphological features of a large sample of whitetailed deer from a previously unharvested herd. Body weights, chest girths, hindfoot lengths, lower mandible lengths, and antler measurements are analyzed by sex and age classes and growth patterns are discussed. Body weights and antler measurements are used to compare general condition of the herd with that of deer in nearby hunted range. The sample was obtained during a controlled harvest to reduce herd size on Crab Orchard National Wildlife Refuge (CONWR), Williamson County, Illinois (Roseberry et al. 1969). All deer were taken from a 7,285-ha (18,000-acre) portion of the Refuge that normally is closed to hunting. The herd was first established in 1942 and has been under intensive study since 1960 by the Cooperative Wildlife Research Laboratory (CWRL) of Southern Illinois University at Carbondale. The habitat, which is considered ideal for deer (Hawkins et al. 1971), has been described previously (Autry 1967, Hawkins and Klimstra 1970). Population density prior to the January 1966 special harvest was estimated to be 1 deer/3.2 ha (1 deer/8 acres) (Autry 1967). The authors are indebted to the many graduate and undergraduate workers of the Cooperative Wildlife Research Laboratory who aided in the collection of data. We also acknowledge officials of the Crab Orchard National Wildlife Refuge and personnel of the Illinois Department of Conservation for assistance. This paper is a contribution from Project No. 15 of the Laboratory: Big Game Investigations. METHODS AND MATERIALS All harvested deer were processed at one of two check stations operated by Laboratory personnel. The animals initially were weighed 0.45 kg (1 pound) with a Viking spring balance, eviscerated, then reweighed. The maximum chest girth of all deer with rib cage intact was measured ? 0.32 cm (1 inch) with a flexible tape measure. Length of the hindfoot from hock to the tip of the longest claw was measured by the same procedure (Brohn and Robb 1955, Park and Day 1942). Antler beam diameter was measured to the nearest 1.0 mm with a vernier caliper. The beam diameter was taken 2.54 cm (1 inch) above the burr and, when possible, did not include bony protuberances (Anderson and Medin 1969). Antler length was measured ? 0.32 cm 48 J. Wildl. Manage. 39(1):1975 This content downloaded from 40.77.167.54 on Sat, 14 May 2016 06:18:18 UTC All use subject to http://about.jstor.org/terms MORPHOLOGICAL CHARACTERISTICS OF DEER * Roseberry and Klimstra 49 ('s inch) with a flexible steel tape measure along the outside of the main beam from burr to tip. Length and diameter were recorded from the left beam, but the undamaged right beam was measured when the left was damaged. All antler protuberances over 2.54 cm long, excluding brow tines, were counted (as the number of antler points) on both beams. A lower mandible was removed from most animals for purposes of age determination. Age classes in this study were established on the basis of tooth eruption and wear (Severinghaus 1949). Total length of the mandible, from its most anterior point to the posterior rim of the angle of ramus (dentary length) was measured to the nearest 1.0 mm with a modified meter rule. The distance between the alveola of the anterior premolar and the corner incisor (diastema length) was measured to the nearest 0.1 mm with a vernier caliper (Bergerud 1964). All data were placed on 80-column IBM cards and processed with an IBM 370/155 computer at the data processing facilities of Southern Illinois University at Carbondale.