Effects of canine parvovirus on gray wolves in Minnesota

Long-term effects of disease on wild animal population demography is not well documented. We studied a gray wolf (Canis lupus) population in a 2,060-km² area of Minnesota for 15 years to determine its response to canine parvovirus (CPV). The CPV had little effect (P > 0.05) on wolf population size while epizootic during 1979-83. However, after CPV became enzootic, percentage of pups captured during summer-fall 1984-93 and changes in subsequent winter wolf numbers were each inversely related to the serological prevalence of CPV in wolves captured during July-November (r² = 0.39 and 0.72, P = 0.05 and < 0.01, respectively). The CPV antibody prevalence in adult wolves increased to 87% in 1993 (r2 = 0.28, P = 0.05). However, because population level remained stable, CPV-induced mortality appeared to compensate for other mortality factors such as starvation. We -predict that the winter wolf population will decline when CPV prevalence in adults consistently exceeds 76%. The CPV may become important in limiting wolf populations.