The threat of deer
Damage to beech forest by fallow deer
Deer cause damage to native forests by feeding on forest plants, trees and seedlings. By targeting these plants, deer can change the composition of the forest understorey.
When deer populations get too large, favourite plants like schefflera, broadleaf, three-finger, hen and chicken fern and lancewood are all but removed from the ground tier in forest understoreys. Plants like alpine buttercup, Spaniard grass and tall tussocks are damaged by deer in subalpine habitats.
In New Zealand, deer have no natural predators (apart from hunters) and apart from occasional instances of bovine Tb, are relatively healthy. Whilst red deer and sika compete where their ranges overlap, none of the other deer species in New Zealand are competing for food.