Ecological and physiological factors influencing the use of mineral licks by Stone’s sheep (Ovis dalli stonei)

Access to trace minerals is essential to the physiological functions of ruminant species. Deficiency in essential minerals can cause adverse effects ranging from reduced growth to impaired metabolic function and fitness to mortality of adults and neonates. Ungulates commonly practice geophagia at areas referred to as “licks”, where they obtain minerals presumably lacking in their diet. We used local knowledge and GPS collar data from 19 Stone’s sheep (Ovis dalli stonei J.A. Allen, 1897) in the Cassiar Mountains of northwestern British Columbia, Canada, to locate mineral licks. We used the location data from 18 collared female sheep and fractional regression to test 13 model hypotheses that explained the frequency and timing of visitation to five licks. Hypotheses represented the physiological traits of collared sheep, site elevation, vegetation, adjacency of human disturbance, and mineral composition of the soil at the lick. We found that visitation was best described by models that included nursing status of ewes, concentration of magnesium and sodium in the soils, and the elevation of the mineral lick. These findings supported our prediction that post-parturient ewes would use mineral licks at a greater rate than ewes without lambs. Location data for one Stone’s sheep ram were analyzed, and this individual spent a greater proportion of his time at licks than all ewes in the study. Our results suggest that mineral licks are an important habitat feature for Stone’s sheep