Movements, resource selection, and risk analyses for parasitic disease in an expanding moose population in the northern Great Plains

Little is known regarding moose ecology in North Dakota, and a decline in moose in northeastern North Dakota may be linked to parasites of white-tailed deer (Parelaphostrongylus tenuis and Fascioloides magna). I investigated the ecology of moose, including the potential effects of parasitic disease. I used global positioning system collars to estimate home ranges and habitat selection and collected fecal samples for diet estimates. I reviewed historical data and examined livers moose for evidence of F. magna infection. I examined 3730 white-tailed deer for P. tenuis and investigated whether prevalence had increased since 1991. I modeled the relationship of climate, habitat and deer density to P. tenuis prevalence and sampled gastropod intermediate hosts to determine habitats functioning in P. tenuis transmission. I estimated moose harvest rates, investigated climate trends, and compared moose population trends to climate for three areas. Finally, I created a risk map for P. tenuis infection that incorporated climate, deer density and habitat.;Home ranges (F1 = 30.9, P < 0.001) and habitat use (F 1 = 30.9, P < 0.001) differed between study sites. Moose selected for wooded habitats, and primarily consumed woody browse (> 65%). Habitat spatial pattern likely influenced home range size, and moose range expansion to the prairie appears related to human-induced habitat change. Historical data revealed that F. magna is endemic to North Dakota, although this parasite was absent in moose livers collected from 2002-2003. This parasite is probably not a primary factor in moose declines, and a lack of permanent wetlands may limit transmission. P. tenuis prevalence in deer was 14%, and had increased since 1991 (P = 0.05). A model of growing season precipitation, winter temperature, and growing season temperature best predicted prevalence (r2 = 0.84). Gastropod sampling suggested that woodlands are critical to P. tenuis transmission. Harvest rates ranged from 16.8-26.7%. Summer temperatures were cooler; May-June precipitation increased, and growing season lengthened. In northeastern North Dakota, P. tenuis risk was higher, and population trends were correlated with climate. Moose declines are likely due to overexploitation and increasing P. tenuis transmission resulting from a wetter climate and increased deer abundance.