Sex-Specific Associations Between Parasite Fecal Egg Counts and Activity Budgets in Wild Bighorn Sheep

Abstract

Parasites impose energetic and physiological costs on their hosts, potentially influencing behavioural time budgets, yet responses may vary among parasite taxa and host sexes. In this study, relationships between parasite burden and activity budgets in free-ranging bighorn sheep (Ovis canadensis) in southwestern Alberta, Canada were investigated. Behavioural observations and fecal samples were collected over seven months, and fecal egg, larval, and oocyst counts were used to quantify infection with multiple gastrointestinal helminth, lungworm, and protozoan taxa. Generalized linear mixed models examined associations between parasite burden and the proportion of time allocated to grazing, rumination, and movement while accounting for age, sex, and parasite-by-sex interactions. Females spent a greater proportion of time grazing than males. Grazing also showed weak evidence of sex-specific associations with lungworm larval counts and Trichuris fecal egg counts. Rumination was associated with a significant interaction between sex and Nematodirus fecal egg counts, indicating that males and females differed in their behavioural responses to this parasite. No predictors were associated with the proportion of time bighorn sheep spent moving. Overall, behavioural responses to parasitism showed stronger evidence for sex-dependent relationships than for consistent main effects of parasite abundance. These findings highlight the complexity of behavioural responses to parasitism in wild ungulates and suggest that host sex may influence how parasite infections are reflected in time allocation to different activities.

The authors' abstract, as published at the source. Pathogens, 2026 · DOI ↗