The benefits of being in a bad neighbourhood: plant community composition influences red deer foraging decisions

摘要

Diet selection by mammalian herbivores is often influenced by plant community composition, and numerous studies have focused on the relationships between herbivore foraging decisions and food/plant species abundance. However, few have examined the role of neighbour palatability in affecting foraging of a target plant by large mammalian herbivores. We used a large-scale field dataset on diet selection by red deer Cervus elaphus in Fiordland National Park, New Zealand to: (1) estimate the palatability of native forest plant species to introduced deer from observed patterns of browse damage; and (2) examine whether intraspecific variation in browsing of plants can be related to variation in the local abundance of alternative forage species. Overall, 21 of the 53 forest species in our dataset were never browsed by deer. At a community level, plants were more likely to be browsed if they were in a patch of vegetation of high forage quality, containing high abundances of highly palatable species and/or low abundances of less-palatable species. Our findings suggest that deer make foraging decisions at both a coarse-grain level, selecting vegetation patches within a landscape based on the overall patch quality, and at a fine-grain level by choosing among individual plants of different species.