TREE SELECTION FOR ANTLER RUBS BY WHITE-TAILED DEER. AARON M. GIVEN, 195 East Autumn Ridge Road, Carbondale, IL 62901, USA

Transcription

1 TREE SELECTION FOR ANTLER RUBS BY WHITE-TAILED DEER AARON M. GIVEN, 195 East Autumn Ridge Road, Carbondale, IL 62901, USA Abstract: Antler rubs by white-tailed deer(odocoileus virginianus) were used for study on an isolated section of the Crab Orchard National Wildlife Refuge in Southern Illinois. I examined tree species and the diameter of tree at the midpoint of the rub. Species selected for rubbing included eastern red cedar(juniperus virginiana), sumac(rhus sp.), black walnut(juglans nigra), and boxelder(acer negundo), but could not conclude the deer select specific tree species for rubbing. Aromatic species were preferred over nonaromatic species. White-tailed deer seemed to prefer trees with a mean diameter of cm. Keywords: antler rubs, Odocoileus virginianus, tree selection, Southern Illinois, whitetailed deer. Scent-marking behaviors have been studied for a number of ungulates including moose (Alces alces; Bowyer et al. 1994), elk (Cervus elaphus; Bowyer and Kitchen 1987), roe deer (Capreolus capreolus; Johansson and Liberg 1996), and white-tailed deer (Odocoileus virginianus; Benner and Bowyer 1988, Miller and Marchinton 1999). Scent-marking behaviors of white-tailed deer include antler rubbing of trees, which is practiced by males prior to and during rut (Kile and Marchinton 1977). Antler rubs are made by stripping bark from a portion of a small tree with the antlers and then rubbing this area with the forehead (Kile and Marchinton 1977, Miller et al. 1987). During rut, sudoriferous glands in the forehead secrete pheromones that act as olfactory signals to other deer that become increasingly active during the breeding season(atkeson and Marchinton 1982). Antler rubs are used as signposts to establish white-tailed deer dominance hierarchies prior to the breeding season (Kile and Marchinton 1977). Miller et al. (1991)

2 hypothesized that the occurrence of rubs well into the mating season suggests that they also help to maintain hierarchies throughout that period. Antler rubs serve other functions among ungulates, such as visual display of dominance (Benner and Bowyer 1988), auditory display of dominance (Miller et al. 1987), and helping induce estrus in females (Sawyer et al. 1989, Bowyer et al. 1994). The following objectives will be used to understand tree selection for antler rubs by white-tailed deer: 1) determine tree species preferred by white-tailed deer for rubs, 2) determine if aromatic trees are selected over non-aromatic trees, and 3) examine the influence of tree diameter on selection. I will test the following null hypotheses: 1) white-tailed deer exhibit no preference in tree species to rub, 2) there is no difference between the selection of aromatic trees and non-aromatic trees, and 3) tree diameter does not influence selection for deer rubs. METHODS Study area My study area was a 16.2 ha section of Crab Orchard National Wildlife Refuge isolated from the main refuge area in Carbondale, Illinois. The area is located 8.5 km west of the main part of the Refuge. The site is characterized as mixed hardwood forest with intermixed conifers dominated by eastern red cedar(juniperus virginiana). Small farm plots of soy beans(glycine max), corn(zea mays), and clover(trifolium sp.) border the area on the North and South. Houses border on the West and a cow pasture borders on the East. Sampling procedures The study area was searched for antler rubs from 6 to 13 November New and old rubs were recorded. Information recorded at each rubbed tree included tree species and diameter at the midpoint of the rub. All lengths were measured to the nearest 0.1 cm. Characteristics of trees with rubs were compared with those trees available, which

3 were located from a random starting point by using the Point-Quarter Technique(Cox 1996). In total, 77 trees were randomly selected for comparison to rubbed trees. Selection of trees by bucks was evaluated using a Mann-Whitney U test. The comparison between aromatic and non-aromatic tree species and diameter of tree at midpoint of the rub was assessed using Chi-square analysis. RESULTS Forty rubs were located; 13 of 19 species of trees were rubbed by deer (Table 1). Deer selected eastern red cedar(juniperus virginiana), sumac(rhus sp.), black walnut(juglans nigra), and boxelder(acer negundo); while sugar maple(acer saccharum), sassafras(sassafras albidium), black cherry(prunus virginiana), autumn olive(elaeagnus sp.), black locust(robinia pseudoacacia), white oak(quercus alba), and black hickory(carya texana) were rubbed in proportion to their availability (Table 1). Shingle oak(quercus imbricaria), American elm(ulmus americana), hackberry(celtis occidentalis), ash(fraxinus sp.), flowering dogwood(cornus florida), northern red oak(quercus rubra), hawthorn(crataegus sp.), and common locust(gleditsia triacanthus) were avoided (Table 1). Tree species selection was not statistically significant(u = 73, U = 122) with the critical value of 141. The diameter (mean + SD) of trees with rubs ( cm) differed (X 2 = 2.76, 1 df, P < 0.1) from that of available trees ( cm). Of trees with rubs, 55% had a diameter between m, 22.5% between m, 10% between m, and 12.5% between m (Table 2). Aromatic trees with rubs differed (X 2 = 9.0, 1df, P < 0.1) from that of non-aromatic tree with rubs, as aromatic trees were rubbed more frequently.

4 DISCUSSION Results suggest that it seems that there is no preference in tree species for antler rubs. Kile and Marchinton (1977) concluded that bucks in Georgia are highly selective in their choice of tree species and that physical characteristics of the trees are involved. In contrast, Miller et al. (1987) reported that trees did not appear to be selected disproportionately to their availability. Eastern red cedar was the most heavily rubbed species(35%) in proportion to their availability (12.5%). Sumac and black cherry were also rubbed in higher proportion to their availability. Kile and Marchinton (1977) also concluded that white-tailed deer selected aromatic species such as shining sumac(rhus copallina) and black cherry(prunus virginiana) for rubs, but seemed to avoid eastern red cedar(juniperus virginiana), because few were available in the appropriate size class. Miller et al. (1987) reported that white-tailed deer in Georgia rubbed trees that were most abundant as reflected by their availability. Benner and Bowyer (1988) suggested that aromatic properties may have been a factor in determining whether trees were rubbed by deer in Maine. However, they also reported that aromatic conifers were avoided. Reasons for this difference may relate to the abundance of the eastern red cedar. Studies in Maine (Benner and Bowyer 1988) and Georgia(Kile and Marchinton 1977) reported lower availability for eastern red cedars. Texture of the bark is a property I did not consider, but previous studies have reported that deer prefer smooth barked trees over rough barked ones, devoid of low branches and thorns(nielson et al. 1982, Kile and Marchinton 1977). White-tailed deer selected smaller diameter trees to rub compared to availability. Kile and Marchinton(1977) and Benner and Bowyer (1988) reported that white-tailed deer concentrated rubs on trees that were cm in circumference. Miller and Marchinton (1999) found a mean diameter of rubbed trees to be 2.4cm. Similarly, Oehler et al. (1995) found a mean diameter of 2.3 cm.

5 LITERATURE CITED Atkeson, T. D., and R. L. Marchinton Forehead glands in white-tailed deer. Journal of Mammology 63: Benner, J. M., and R. T. Bowyer Selection of trees for rubs by white-tailed deer in Maine. Journal of Mammology 69: Bowyer, R. T., and D. W. Kitchen Significance of scent-marking by roosevelt elk. Journal of Mammalogy 68: , V. V. Ballenberghe, and K. R. Rock Scent marking by Alaskan moose: characteristics and spacial distribution of rubbed trees. Canadian Journal of Zoology 72: Cox, G. W Vegetative analysis. Pages in M. J. Kemp, editor. Laboratory manual of general ecology. Seventh edition. Wm. C. Brown Publishers, Dubuque, Iowa, USA. Johansson, A., and O. Liberg Functional aspects of marking behavior by male roe deer (Capreolus capreolus). Journal of Mammology 77: Kile, T. L., and R. L. Marchinton White-tailed deer rubs and scrapes: spatial, temporal, and physical characteristics and social role. American Midland Naturalist 97: Miller, K. V., K. E. Kammermeyer, R. L. Marchinton, and E. B. Moser Population and habitat influences on antler rubbing by white-tailed deer. Journal of Wildlife Management 51:62-66., R. L. Marchinton, and P. B. Bush Signpost communication by whitetailed deer: research since Calgary. Applied Animal Behavior Science 29: , and R. L. Marchinton Temporal distribution of rubbing and scraping by a high-density white-tailed deer, Odocoileus virginianus, population in Georgia. Canadian Field Naturalist 113:

6 Nielsen, D. G., M. J. Dunlap, and K. V. Miller Pre-rut rubbing by white-tailed bucks: nursery damage, social role, and management options. Wildlife Society Bulletin 10: Oehler, M. W., Sr., J. A. Jenks, and R. T. Bowyer Antler rub by white-tailed deer: the importance of trees in a prairie environment. Canadian Journal of Zoology 73: Sawyer, T. G., R. L. Marchinton, and K. V. Miller Response of female whitetailed deer to scrapes and antler rubs. Journal of Mammology 70: Table 1. Trees selected and avoided for rubbing by white-tailed deer in Illinois.

7 %rubbed %available (n = 40) (n = 77) Juniperus virginiana a Rhus sp. a Acer saccharum Juglans nigra a Sassafrass albidium a Quercus imbricaria Acer negundo Elaeagnus sp Prunus virginiana a Robinia pseudoacacia Quercus alba Carya texana Ulmus americana Celtis occidentalis Fraxinus sp Cornus florida a Crataegus sp Gleditsia triacanthus Quercus rubra a Aromatic species.