Data from: Use of environmental sites by mule deer: a proxy for relative risk of chronic wasting disease exposure and transmission

Prions that cause chronic wasting disease (CWD) in cervids can remain
infective for years outside the host. Infectious cervids shed prions for a
long time, consequently depositing prions in frequently used areas. These
environmental prions are important in CWD epidemiology. Unfortunately,
effective tools for quantifying CWD prions in soil, water, and other
environmental sources are not currently available. Our goal was to
investigate relative differences in visits by mule deer (Odocoileus
hemionus hemionus) to various environmental site types as an indicator of
the relative risk of prion contamination and disease transmission. For
this, we deployed a system of triggered-by-movement cameras at eight site
types in a CWD-endemic area in Saskatchewan, Canada. We first assessed
whether the relative differences among site types in the frequency of
visits by mule deer of any sex-and-age class, males, and females varied by
season and site type. We then assessed whether the rate of behaviors with
a high risk of environmental prion transmission (either contamination or
acquisition) differed by season and site type. Finally, we assessed
whether the intensity of visitation, based on the number of animals per
picture, differed by season and site type. We found that grain sources and
beds were key attractants for mule deer: (1) The greatest number of
pictures with mule deer per camera-day occurred at grain sources across
all seasons, except in fawning, when beds were the most visited sites; (2)
during pre-rut and early gestation, mule deer visited grain sources at
least twice as often as most other sites; (3) females were more likely to
visit beds and grain sources, but there was no significant site
preferences for males after accounting for season; (4) mule deer were most
likely to be pictured contacting the environment at grain sources in early
gestation; and (5) beds and grain sources were the most intensively
visited sites. We also found that environmental contacts at waterholes
were more frequent during spring. We discuss the potential importance of
various sites in the transmission of CWD and how their modification could
potentially reduce the risk of prion environmental exposure among mule
deer.