Mule deer spatial association patterns and potential implications for transmission of an epizootic disease

Abstract

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.

Evaluation of a Test and Cull Strategy for Reducing Prevalence of Chronic Wasting Disease in Mule Deer (Odocoileus Hemionus)

“…By spring 2007, we had accumulated permissions to access nearly 1,400 separate private property parcels for deer capture and testing in addition to public and municipal lands, but this represented less than 20% (1,387/7,459) of the parcels in the area. Data on individual deer movements to measure home ranges or to identify clear social partitioning were not collected, but anecdotal field observations were consistent with patterns reported for mule deer elsewhere (Cullingham et al 2011;Mejía-Salazar et al 2017, 2018.…”

Giraffe (Giraffa camelopardalis) social networks in areas of contrasting human activity and lion density

“…A social network approach is useful because it provides a validated, quantitative approach to characterise both individual-and population-level social structure (Krause et al, 2007). Studying the social network of populations allows greater insight and understanding of processes which support disease transmission (Mejía-Salazar et al, 2017;VanderWaal, Atwill, et al, 2014), social learning (Hobaiter, Poisot, Zuberbühler, Hoppitt, & Gruber, 2014) and the evolution of social strategies (Brent et al, 2015;Cameron, Setsaas, & Linklater, 2009).…”

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

“…(), the applicability of CWD dynamic models can be greatly improved by expanding these models by considering both the non‐random social interactions between individuals (Mejía‐Salazar et al. ) and the environmental dynamics of prion transmission. Until such time that analytical techniques are developed to detect concentrations of CWD prions in the environment, our results can be immediately used to rank the relative importance of various environmental sources of CWD prions in future epidemic models for this region.…”

“…, Mejía‐Salazar et al. ), we divided the year into five seasons, which were fawning, pre‐rut, rut, early gestation, and late gestation. These seasonal categories were selected based on mule deer movement patterns (Silbernagel ) and reflect important behavioral, physiological, climatic, and agrarian changes occurring to mule deer and their habitat in the study area (Table ).…”

“…Found mule deer carcasses from other ongoing studies involving radio-collared deer (Silbernagel et al 2011, Reiczigel et al 2015, Mej ıa Salazar et al 2016, Mej ıa-Salazar et al 2017a). Available all year, but mainly in early gestation and rut (Appendix S1: Fig.…”