Forage Availability and the Diet of Fallow Deer (dama Dama) in the Blue Mountains, Otago

Fallow deer did not prefer either of the two main canopy species (silver beech, Nothofagus menziesii, and radiata pine, Pinus radiata), or any of the common indigenous shrubs, ferns, herbs and monocotyledons in three habitat types (beech, shrub-hardwood, and exotic forest). They did prefer all the common sub canopy tree species, and these comprised the bulk of diet in all habitats. Broadleaf (Griselinia littoralis) was the most important single food, with litterfall being its dominant source. The most important non-woody foods were lichen and fungi (beech forest) and introduced grasses (exotic forest). Total forage availability did not differ between habitats (590 ±148 kg of dry matter ha), but composition did. Preferred foods (other than the introduced grasses) were scarce, particularly in the beech forest. A comparison of probable food production and use within the browse zone indicated that, at present densities, deer were not likely to prevent regeneration of the less preferred species (including silver beech). In the beech forest, regeneration of most sub canopy tree species will be minimal while deer densities remain near present levels (0.1 deer ha). However, the biomass of silver beech, shrubs, ferns, lichen, and fungi appears adequate to sustain the current deer population even if most of the preferred tree species disappear.