Meningeal Worm in White-Tailed Deer in Northwestern Ontario and Moose Population Densities

Abstract

The prevalence of the roundworm Parelaphostrongylus tenuis Dougherty in white-tailed deer (Odocoileus virginianus) was inversely related to moose (Alces alces) population densities. First stage larvae of P. tenuis were found in 286 (47.4 percent) of the 603 deer pellet groups examined. J. WILDL. MANAGE. 37(3):327-330 Karns (1967) found that the prevalence of P. tenuis varied from one part of Minnesota to another. Where prevalence was high in white-tailed deer, moose populations were low, and where prevalence was low in white-tailed deer, moose populations were relatively higher suggesting a relationship between P. tenuis and moose population densities. A recent study of the distribution of meningeal worm P. tenuis in Canada (Bindernagel and Anderson 1972) has also shown that prevalence of the parasite in white-tailed deer varies considerably from one place to another. This raised the question whether variations in the prevalence of meningeal worm in deer existed in the Kenora area of Ontario and whether moose and deer population densities might be related to or correlated with these variations. I wish to acknowledge the assistance of Dr. John Bindernagel and the Conservation Officers of the Kenora area. I further wish to thank Dr. Roy Anderson for his encouragement and helpful suggestions during this study. MATERIALS AND METHODS Fecal pellet groups of white-tailed deer were collected from the surface of the snow during January, February, and March of 1970 and 1972. An attempt was made to collect at least ten pellet groups from each area, but this varied with the circumstances. Each fecal pellet group was stored in a separate plastic bag and kept frozen until analyzed. The pellet group collections were widely distributed throughout the study are in order to include areas of high and low deer densities. Dr. John Bindernagel examined 193 of the 603 fecal pellet groups collected in this study. A Baermann apparatus was used to collect first-stage larvae of P. tenuis. After a minimum of three hours a small amount of water was drawn off into a Petri dish and examined under a dissecting microscope (25-50x). The characteristic firstst ge larvae of P. tenuis (Anderson 1963), usually assume a comma-like position, are nongranular in appearance and have a dorsal spine on the tail. First-stage larvae are resistant to freezing temperatures. Moose and deer populations in two portions of the study unit (Lake of the Woods and Sand-Sydney lakes area) were determined by a pellet group census (Table 1). Pellet group counts were randomly distributed cluster samples with a maximum of 80 plots per cluster. The field staff of the Kenora area were asked to rate moose population densities in the 56 specific areas (Fig. 1) where pellet groups were collected. The ratings were given numerical values one through five, with one equaling one moose per five square miles, two equaling one moose per four square miles, etc. The prevalence of J. Wildl. Manage. 37 (3):1973 327 This content downloaded from 157.55.39.139 on Sat, 26 Nov 2016 04:06:43 UTC All use subject to http://about.jstor.org/terms 328 MENINGEAL WORM IN DEER Saunders Table 1. Moose and white-tailed deer densities and prevalence of P. tenuis in the Lake of the Woods and Sand-Sydney lakes area of the Kenora area of Ontario. Lake of the Woods Sand-Sydney lakes Deer Moose Deer Moose Area (square miles) 2111 2111 1004 1004 Estimated population (per square mile) 12.66 0.97 10.38 2.23 Deer pellet groups examined 145 -52 Deer pellet groups infected 82 -14 -Prevalence (percent) 56.5 -26.0 -larvae in feces was related to moose population indices (Table 2).