Foliar fibre predicts diet selection by invasive Red Deer Cervus elaphus scoticus in a temperate New Zealand forest

1. There is much interest in how herbivores interact with plant communities, but the association between foliar traits and the feeding behaviour of invading browsing mammals has not been explored in this context. 2. We investigated whether eight foliar traits predicted the preferences of invasive Red Deer for 21 woody plant species in lowland forest in southern New Zealand. 3. The four models with substantial support for predicting variation in two indices of diet selection all included one or more traits related to foliar fibre (acid detergent fibre; acid detergent cellulose; acid detergent lignin). In all models the coefficients were negative, indicating that as the concentrations of foliar fibre increased, the preference of deer for foliage decreased. 4. Our results thus link the feeding behaviour of Red Deer with previously demonstrated shifts in the composition of New Zealand forests towards understorey species and leaf litter with high concentrations of foliar fibre.