Animal social behaviour can have important effects on the long-term dynamics of diseases. In particular, preferential spatial relationships between individuals can lead to differences in the rates of disease spread within a population. We examined the concurrent influence of genetic relatedness, sex, age, home range overlap, time of year, and prion disease status on proximal associations of adult Rocky Mountain mule deer (Odocoileus hemionus hemionus) in a chronic wasting disease endemic area. We also quantified the temporal stability of these associations across different sex, age, and disease status classes. We used three years of high frequency telemetry data from 74 individuals to record encounters within 25 m of each other, and to calculate seasonal home range overlap measured by volume of intersection (VI). The strength of pairwise spatial association between adult mule deer was independent of genetic relatedness, age and disease status. Seasonal variation in association strength was not consistent across years, perhaps due to annual changes in weather conditions. The influence of home range overlap on association strength varied seasonally, whereby associations were stronger in pre-rut and fawning than in the rest of the seasons. The sexes of individuals also interacted with both VI and season. At increasing levels of VI, associations were stronger between females than between males and between females and males. The strongest associations in pre-rut were between males, while the strongest in rut were between females and males. The temporal stability of associations was markedly dependant on the sex and the diagnosis of the associating pair. Our findings highlight the importance of considering concurrent effects of biological and environmental factors when seeking to understand the role of social preference in behavioural ecology and disease spread. Applying this knowledge in epidemiological modelling will shed light on the dynamics of disease transmission among mule deer.

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.