We did not have deer die within two months of capture from natural causes or

We did not have deer die within two months of capture

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nodes only. We did not have deer die within two months of capture from natural causes or capture myopathy. Deer mortalities resulted from predation (coyote (n = 5) and mountain lion (n = 5)), vehicle collision (n = 3), hunt- ing outside of Wind Cave National Park (n = 5), lethal removal by law enforcement (n = 4), and unknown causes (n = 6). Testability for CWD (19/28, 68%) and number of CWD-positive (8/19, 42%) deer varied by source of mortal- ity (Table 1). Predation by coyotes and mountain lions was the primary mortality factor and also the least likely to be able to be tested for CWD (50%) because tissues necessary for sampling were no longer present due to consumption or scattering. Unknown causes, the second most com- mon source of mortality, resulted from carcasses that were not testable (50%). Deer mortalities from human-derived sources (vehicle collisions and hunting) were more likely than other sources of mortality to provide a sample for CWD testing ( χ 2 = 4.47, p = 0.03) than those from preda- tion events. Females were six times more likely than males to be killed by a predator than by a human source (OR = 6.67, p = 0.078). There was no apparent age bias by mortality type, but our study population was primarily adult animals. If only mortalities were tested, observed CWD prevalence was 42%. Observed prevalence from human-induced mortalities only was 20%. No carcasses had indications of malnutri- tion, apparent disease, or heavy internal or external parasite loads. A few deer had positive titers for all serum tests, with the exception of Johne’s disease, throughout the three years of study (Table 2); there was no difference between sexes. Exposure to EHD (13%) was most commonly identified, followed by WNV (12%), MCF (11%), BT (11%) and 1 individual identified with antibodies to BVD. None of the Table 1. Cause-specific mortalities of 28 deer (of 67 collared) at Wind Cave National Park, South Dakota, USA, from February 2003 to December 2005 and chronic wasting disease (CWD) status of testable samples, either CWD-positive (+), CWD Non-detect (–), or Non-testable. MORTALITY CWD + CWD – Non-testable Coyote 1 3 1 Mountain lion 0 1 4 Vehicle collision 1 2 0 Hunting outside study area 1 3 1 Lethal removal in study area 3 1 0 Unknown 2 1 3
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4 carcasses examined had gross lesions consistent with these infectious diseases. There was no association between infec- tious disease exposure based on positive titers and future mortality or CWD infection. We constructed five known-fate models to examine differences in survival as a function of sex and age (Table 3). Constant survival was the best supported model with 0.36 of the model weight ( w ), however, all model structures were within four QAIC c units indicating little power in the data to detect covariate differences. Kaplan–Meier staggered-entry indicated a nearly constant pattern in survival with a lin- ear trend over 34 months (y = –0.016x + 20.27, r 2 = 0.985); constant survival was estimated at 0.9739 ± 0.0077 SE per month [ S annual = 0.7284 ( ± 0.069 SE)] based on the best supported model. Given the expected value of annual survival, the average life expectancy of deer was 3.2 years with a 95% CI [confidence interval] of (1.91, 6.87 years).
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  • Winter '20
  • Biology, Deer, White-tailed deer, Elk, Chronic Wasting Disease

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