Variability in the feeding ecology and behaviour of extant European reindeer subspecies inferred from dental microwear texture analysis

Reindeer (Rangifer tarandus), a keystone species of Arctic and subarctic ecosystems, display remarkable ecological and behavioural plasticity, occupying environments ranging from open tundra to closed taiga forests. However, little is known about dietary variability among wild forest reindeer (R.t. fennicus) or semi-domesticated populations (R.t. tarandus) inhabiting similar forested landscapes. This study investigates the feeding ecology of Finnish reindeer through dental microwear texture analysis (DMTA). We analysed individuals from five populations in central and northern Finland, sampled in autumn and winter, to assess dietary differences across regions, sexes, and seasons. Results reveal that Finnish reindeer exhibit distinct dietary patterns compared to other European populations, characterised by high complexity (Asfc), moderate anisotropy (epLsar), and low heterogeneity (HAsfc) values. No significant differences were observed between the two subspecies or between sexes, suggesting limited dietary variability within and among populations, likely due to shared habitats and low population densities that reduce intraspecific competition. However, seasonal comparisons show higher anisotropy and lower heterogeneity in winter, reflecting a less diverse diet likely linked to increased lichen consumption. These findings provide a valuable reference for understanding the feeding ecology of European reindeer populations and highlight the role of environmental adaptation over phylogenetic constraints in shaping dietary behaviour.