Feral Deer include Red Deer (Cervus elaphus) (including hybrids), and Fallow Deer (Dama dama).  These feral deer are included in Canterbury's Regional Pest Management Strategy in the Biodiversity Protection Programmes.  The aim of the programme is that over the duration of the Strategy, feral deer are maintained at levels sufficient to ensure that biodiversity values are protected in targeted areas of the Canterbury Region.

General

Red deer are present throughout the Region apart from Banks Peninsula. Fallow deer are confined to moderate numbers in isolated scrubfilled gullies on private land in South Canterbury and a number of small herds are present in other parts of Canterbury.  Deer occur in tussock grassland, forest, scrub and riparian areas. Their density is believed to be about 2 - 5 per square kilometre in most of the South Island forest areas, and near zero in tussock grassland and open areas where they are susceptible to hunting. Their capacity to increase appears to be slightly under 30 per cent per year, although hunting pressure means that these rates of increase are rarely seen. Red deer are controlled only by hunting pressure and have no other predators. Rates of dispersal are high for young males, but older males and females remain closer to their home range.  Red deer are selective feeders, with about 80 per cent of their feed obtained by browsing and the remainder through grazing. They have strong food preferences, and favour Pseudopanax species (lancewoods), Coprosma species, pate, broadleaf, and the fern Asplenium bulbiferum. In most forests these are now severely depleted and deer switch to less palatable species. They even eat relatively unpalatable beech, podocarps and woody shrubs when more palatable shrubs have been eliminated. Deer have considerably altered many forests, and the preferred browsing species are now rare. Fallow deer are thought to have severe impacts in beech forests, although the impacts are not as well studied because fallow deer are less common.

Adverse effects of feral deer

Deer affect the sustainability of the native forest ecosystems by modifying its structure and composition. Local reductions of 50-60 per cent in stem frequency and 30 per cent in woody species have been recorded, and they eliminate the understorey, prevent or delay regeneration, and alter botanical biodiversity toward unpalatable species. Many vulnerable species will only regenerate in the near absence of feral deer, and their browsing is presumed to lead to the loss of species diversity. Feral deer populations are sustained in depleted forests by leaves falling from the canopy above, and their populations may remain at levels that are able to continue driving declining patterns of forest diversity.  Red deer may compete with native bird life, and the decline of kokako in the North Island has been attributed in part to the degraded habitat caused by deer and possums. Their effect on South Island bird populations is uncertain, but it is possible that they are similarly affecting native pigeon populations.  Grazing pasture forms only a small part of feral deer feeding. As their numbers are low and confined to less productive pasture types, their economic impact is not likely to be significant.

Environment Canterbury's role

Environment Canterbury can facilitate and assist community and land occupier selfhelp programmes to destroy possums, mustelids, feral cats, feral deer, feral goats, feral pigs and wasps particularly adjacent to areas of high environmental value to complement control operations or in other areas if there is community support for control operations;  For example, the Banks Peninsula possum programme.