Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria

In recent years the Victorian feral deer population and distribution have rapidly increased with analysis by the Victorian Department of Environment, Land, Water and Planning (DELWP) suggesting that the population of deer could be between ‘several hundred thousand up to one million wild animals or more’. The dramatic increase is partially a result of the current legal status of deer, which makes it difficult undertake strategic, large-scale management.

The challenge in managing feral deer is likely to be exacerbated in future, with populations expected to increase significantly over the next thirty years, driven by a combination of climate change, natural dispersal and deliberate releases and farm escapes. Our analysis estimates that even under conservative assumptions, if no significant management action is taken, by 2050 there could be 1.7 to 4.6 million feral deer in Victoria.

While the number of deer in future is uncertain, what is known is the significant economic, social, cultural, and environmental cost imposed by feral deer on the Victorian community.

Frontier Economics was engaged by the Invasive Species Council to examine the economics of managing feral deer in Victoria. As part of this analysis we have identified, and where possible, valued the economic, social, cultural and environmental impacts on society of failing to manage feral deer to an ecologically sustainably level (i.e. at a level at which they are likely to have limited negative impact on the economic, social, cultural and environmental outcomes in Victoria). To the extent that controlling the feral deer population saves economic, social, cultural and environmental costs, these are considered to be an economic benefit arising from the controls.

Drawing on the best available information, our analysis indicates that the cost to the broader community of feral deer could be over $1.5bn (7% discount rate) or $2.2bn (4% discount rate) in present value (PV) terms, over the next 30 years. This estimate is made up of:

• $245m to $350m in economic costs from lost gross margin due to grazing (in PV terms, over the next 30 years, 7% and 4% discount rate, respectively). This assumes 10% of the feral deer population are grazing on farmland, which reduces the opportunity to fully stock that land for grazing, resulting in a reduction in income for the farmer.
• $106m to $144m in economic costs from resources spent managing feral deer (in PV terms, over the next 30 years, 7% and 4% discount rate, respectively). This assumes a farmer spends 20 days a year managing feral deer on their properties.
• $269m to $365m in economic costs from lost forestry production (in PV terms, over the next 30 years, 7% and 4% discount rate, respectively). This assumes a reduction in production of plantations as a result of feral deer grazing and trampling through the forests.
• $576m to $825m in economic costs from deer-related vehicle accidents (in PV terms, over the next 30 years, 7% and 4% discount rate, respectively). This assumes that all future feral deer related crashes on highways within Victoria can be avoided.
• $308m to $474m in social costs from reduced recreation and use values (in PV terms, over the next 30 years, 7% and 4% discount rate, respectively). This is based on the assumption that uses of Victorian national and state parks for recreation will be dampened by 1% due to the impact of feral deer.

Although our analysis has sought to value the benefits (including cost savings) associated with managing feral deer in Victoria, given the availability of information these figures do not capture the full range of potentially significant costs of feral deer in Victoria. These include the impact of feral deer on:

• the other costs of management
• the cost of water supply
• the risk of disease
• Indigenous cultural heritage
• biodiversity
• the health of rivers and waterways

As such, it is likely that the true economic, social, cultural and environmental costs imposed on the community as a result of feral deer in Victoria are larger than our estimate.

Understanding the change in outcomes and the appropriate price is critical to robustly value the economic, social, cultural and environmental benefits of managing feral deer within Victoria. Given the significant impact of feral deer in Victoria, there is likely to be benefit in undertaking further work to better understand the magnitude of the problem, and therefore, the benefits of action.

While there are costs associated with reducing feral deer numbers to sustainable levels, these are unlikely to outweigh the benefits of control. Our analysis suggests that if management is taken in 2022, the cost of removing all feral deer could be between $338m and $581m (depending on the population scenario). This cost would have to rise by around four times before the conservatively estimated benefits of controlling deer was outweighed. Having said this, we acknowledge that both the extent and approach to feral deer management will determine the level of benefits society receives, because different management strategies will have different impacts on the feral deer population, at different costs.

Our findings highlight the need for decisive action to manage the feral deer population in Victoria. The longer control is delayed the larger the population of feral deer and the greater the cost of inaction. In other words, a strategy that quickly and significantly reduces deer numbers will deliver greater benefits than a slower response, while at the same time requiring lower costs to achieve.

These results are inherently uncertain and there are gaps in the available research and primary data on the impacts of specific feral deer in Victoria. However, even if these uncertainties could be resolved with more research, given the conservative approach we have taken, improved information is more likely to increase the benefits of control, thereby reinforcing the conclusion that controlling feral deer is net beneficial.