The Meningeal Worm, Parelaphostrongylus tenuis, a Marginal Limiting Factor for Moose, Alces alces, in Southern Québec

Abstract

We estimated the relative importance of the meningeal worm (Parelaphostrongylus tenuis) as a limiting factor of Moose (Alces alces) populations living in sympatry with White-tailed Deer (Odocoileus virginianus) in southern Québec, using a questionnaire. We recorded 84 cases of moose showing typical signs of infection by the meningeal worm, 61 during the 1983-1992 period. There was close agreement between deer distribution and the location of symptomatic Moose. Signs of infection with the meningeal worm appeared equally between sexes in animals older than 1 year of age, but symptomatic calves were observed less often than expected. We found a significant linear relationship (r2 = 0.80; d.f. = 8) between apparent infection rate (observed cases•10 000 moose-1•yr-1) and estimated deer density. At the scale of hunting zones, we found no evidence of refugia in which moose would be protected from the parasite. Reported cases of symptomatic moose always represented less than 1% of total moose populations; monitoring of 149 radio-collared moose in two areas of southern Québec for other purposes also suggested an apparent annual mortality rate from parelaphostrongylosis of <1%. White-tailed Deer densities are probably not high enough to prevent the establishment of Moose populations anywhere in Québec. This limiting factor, however, diminishes the demographic vigour of infected populations, and the potential hunting harvest.