Seasonal and Interannual Dietary Variation During Winter in Female Svalbard Reindeer (Rangifer Tarandus Platyrhynchus)

Abstract

We investigated dietary variation during three winters in female Svalbard reindeer (Rangifer tarandus platyrhynchus) on the basis of rumen samples from animals culled in early and late winter during 2000–2002. The winter diet was compared to a late summer diet on the basis of samples from 1999, with variations in dietary composition in early and late winter among years also investigated. We conducted our assessment by identifying plant fragments in rumen samples using a point identification method. The effects of season and year on dietary composition of females were tested using non-parametric multifactorial MANOVA. During early winter, the diet seemed to be a function of both plant availability and plant quality, with the latter also highly important for the summer diet. During late winter, restricted forage availability due to snow cover seemed to have influenced dietary composition. We also found dietary variation among years both in early and late winter. We hypothesize that climatic effects previously found on the growth rate of Svalbard reindeer populations may be mediated through interannual variation in their diet where increased summer precipitation and winter rain may affect the dietary composition through decreased availability of forage biomass.