Chronic wasting disease (CWD) is a fatal transmissible spongiform encephalopathy 
affecting white-tailed deer (Odocoileus virginianus), mule deer (Odocoileus 
hemionus), Rocky Mountain elk (Cervus elaphus nelsoni), and moose (Alces alces 
shirasi) in North America. In southeastern Wyoming average annual CWD prevalence 
in mule deer exceeds 20% and appears to contribute to regional population 
declines. We determined the effect of CWD on mule deer demography using 
age-specific, female-only, CWD transition matrix models to estimate the 
population growth rate (λ). Mule deer were captured from 2010-2014 in southern 
Converse County Wyoming, USA. Captured adult (≥ 1.5 years old) deer were tested 
ante-mortem for CWD using tonsil biopsies and monitored using radio telemetry. 
Mean annual survival rates of CWD-negative and CWD-positive deer were 0.76 and 
0.32, respectively. Pregnancy and fawn recruitment were not observed to be 
influenced by CWD. We estimated λ = 0.79, indicating an annual population 
decline of 21% under current CWD prevalence levels. A model derived from the 
demography of only CWD-negative individuals yielded; λ = 1.00, indicating a 
stable population if CWD were absent. These findings support CWD as a 
significant contributor to mule deer population decline. Chronic wasting disease 
is difficult or impossible to eradicate with current tools, given significant 
environmental contamination, and at present our best recommendation for control 
of this disease is to minimize spread to new areas and naïve cervid populations.