Michael J. Lindeman and David M. Forsyth
The Department of Sustainability and Environment (DSE) commissioned the Arthur Rylah Institute for Environmental Research to evaluate the agricultural impacts of deer in Victoria.
We first evaluated temporal and spatial patterns in the numbers of Authority to Control Wildlife (ATCW) permits issued by DSE for deer in Victoria during the 2002–2007 calendar years. The number of permits issued increased from 25 permits in 11 municipalities in 2002 to 178 permits in 23 municipalities in 2007. Most permits (76%) were issued for Sambar Deer Cervus unicolor, followed by Red Deer Cervus elaphus scoticus (24%), Fallow Deer Dama dama (20%) and Hog Deer Axis porcinus (2%). The largest increase in the numbers of permits issued occurred in eastern Victoria, particularly East Gippsland Shire, Murrindindi Shire, Wellington Shire and Yarra Ranges Shire.
The main reasons given by holders of ATCW permits for wanting to control deer were preventing damage to the following agricultural values: pasture, fruit, grapevines, vegetables (especially potatoes), pine and other trees, native tree revegetation, and flowers and foliage. We randomly selected one ATCW permit holder from each of the three main impact types (plantation, competition for pasture and orchard) and visited the property to inspect the impacts and conduct a spotlight survey to estimate the number of deer on the property. At the orchard there was evidence of Sambar Deer breaking the branches of apple, cherry and plum trees, but there was no recent damage and no deer were seen during the spotlight survey. At the cattle farm no impacts directly attributable to deer were observed and the landholder considered the Eastern Grey Kangaroo Macropus giganteus and Common Wombat Vombatus ursinus more serious competitors for pasture than Sambar Deer. In two spotlight counts we observed an average of four European Rabbit Oryctolagus cuniculus, one Common Wombat, four Eastern Grey Kangaroo and four Sambar Deer on the property. An inspection of the farm-forest property revealed that antler rubbing (almost certainly by Sambar Deer) and bark stripping (probably by Sambar Deer but possibly also by Black Wallaby Wallabia bicolor) had damaged about 10% of the surviving 530 Pinus radiata trees 30 cm or more tall, and some were so damaged that they would likely die or would not be saleable. No deer were observed on this property.
Most landholders considered that shooting deer with the aid of a spotlight was the most cost-effective way of minimising the agricultural impacts of deer, and most of this control was provided free-of-charge to the landholder by sporting shooters through the Authority to Control Wildlife permit system.
A method was developed for quickly assessing the extent of bark stripping and antler rubbing by Sambar Deer on Pinus radiata, and spotlight surveys are suggested as the most appropriate method for determining the extent to which deer are competing with livestock for pasture. Further work is required to estimate the impacts of deer on orchards, vineyards and market gardens and to estimate the economic costs of all impact types.