Chronic wasting disease (CWD) is an invariably fatal transmissible spongiform encephalopathy of white-tailed deer, mule deer, elk, and moose. Despite a 100% fatality rate, areas of high prevalence, and increasingly expanding geographic endemic areas, little is known about the population-level effects of CWD in deer. To investigate these effects, we tested the null hypothesis that high prevalence CWD did not negatively impact white-tailed deer population sustainability. The specific objectives of the study were to monitor CWD-positive and CWD-negative white-tailed deer in a high-prevalence CWD area longitudinally via radio-telemetry and global positioning system (GPS) collars. For the two populations, we determined the following: a) demographic and disease indices, b) annual survival, and c) finite rate of population growth (λ). The CWD prevalence was higher in females (42%) than males (28.8%) and hunter harvest and clinical CWD were the most frequent causes of mortality, with CWD-positive deer over-represented in harvest and total mortalities. Survival was significantly lower for CWD-positive deer and separately by sex; CWD-positive deer were 4.5 times more likely to die annually than CWD-negative deer while bucks were 1.7 times more likely to die than does. Population λ was 0.896 (0.859–0.980), which indicated a 10.4% annual decline. We show that a chronic disease that becomes endemic in wildlife populations has the potential to be population-limiting and the strong population-level effects of CWD suggest affected populations are not sustainable at high disease prevalence under current harvest levels.

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Chronic wasting disease (CWD) is an infectious and fatal transmissible spongiform encephalopathy of members of the family Cervidae. Although CWD has been a serious concern among wildlife managers in several states in the United States and 2 Canadian provinces for over a decade, it is not known how CWD affects movement of hosts during the preclinical and clinical phases of disease. We hypothesized that normal movement patterns are altered by CWD. We evaluated migratory status, migration corridors, dispersal behavior, hourly activity patterns, home range areas, and resource selection for white-tailed deer (Odocoileus virginianus) of known CWD status as a means of understanding how CWD infection influenced habitat use and disease spread. We captured deer, tested for CWD by tonsil biopsy, marked deer with radio-transmitters (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010) or global positioning system collars (2006)(2007)(2008)(2009)(2010), and recaptured individuals annually for CWD testing. The proportion of CWD-positive females that migrated was significantly less than CWD-positive males. All deer that were CWD-negative were more active than their CWD-positive cohabitants, which was most pronounced in fall for males when CWD-positive deer were significantly less active throughout the day. Home range areas were small (x ¼ 1.99 km 2 ) and were larger for CWD-negative females than CWD-positive females. Resource selection analyses indicated that all deer, regardless of CWD status, sex, or migratory status selected riparian habitats. Riparian habitats represent high CWD risk areas that should be targeted for potential disease management actions (e.g., surveillance, culling, environmental treatments). Ó

Black bears have delayed implantation with fetal development and lactation energy demands during a period of maternal hibernation and starvation. Pregnant females in a state of diapause had about 23% greater fat depots than non­reproductive females going into hibernation. Fat provided 92% of the total energy for lactation and gestation. Rates of fat loss were 27% and protein loss 58% higher for reproductive females compared to non-reproductive females. The cost of winter reproduction to include gestation and lactation was 1432 kj/day to produce two cubs. While reproduction required elevated protein breakdown, the overall loss was relatively small, perhaps due to a short gestation period and urea recycling.

Bioelectrical impedance analysis (BIA) is a tool used to provide a measure of body water content and total body fat in an organism. Recently, researchers have validated BIA against tritiated water techniques in the laboratory and proposed it as a fast, non-invasive method for assessing body condition in free-ranging black bears. In the present study, we field tested BIA as a plausible tool for investigating body fat utilization during hibernation by three black bear populations in the Rocky Mountains. Body fat content in the fall ranged from a mean of about 39% for a group of large, lactating females down to about 29% by two groups of bears consisting of males and mostly non-lactating females. Daily rates of body fat use were greater for the larger, lactating female group than either of the other two groups. Although the fat data determined by BIA appear useful in terms of trends and relative changes, many of the absolute values are inconsistent and perhaps inaccurate. Because BIA is so sensitive to a variety of factors typical of field conditions, we recommend it not be used as the sole source for assessing body condition of large animals such as black bears.

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