East Anglia: More severe cull ‘needed to stop deer populations spreading out of control’

© Kyle Moore Photography
Red Deer Stag

© Kyle Moore Photography Red Deer Stag - Credit: Kyle Moore

Current approaches to deer management are failing to control a serious and growing problem, according to new research by the University of East Anglia.

Researchers drove more than 1140 miles at night and used thermal imaging and night vision equipment to quantify the population of roe and muntjac deer in a unique study spanning the border of Suffolk and Norfolk.

The results, published today in the Journal of Wildlife Management, show for the first time that present management efforts are not enough to stop populations spreading out of control.

There are more deer in the UK than at any time since the ice age. In the absence of natural predators, populations are continuing to expand - causing a serious threat to biodiversity, as well as road traffic accidents and crop damage.

The research team investigated the numbers, sex ratio and fertility of roe and muntjac deer across 234km sq of forested land and heathland in Breckland, East Anglia, to measure the effectiveness of deer management. It is the first time that such a landscape-scale study has been carried out in Europe and the first time that control efforts have been compared to known numbers.

They found that while deer management appeared to control numbers at a stable level, this was only because thousands of deer are ‘pushed out’ to the surrounding countryside each year, helping drive the further spread of deer.

In the Breckland study area, researchers identified a necessary cull of 1864 muntjac from an estimated population of 3516 (53%) and 1327 roe deer out 2211 (60%) just to offset productivity, with greater numbers needing to be culled if populations are to be reduced. These figures greatly exceed previous cull recommendations for muntjac (30%) and roe (20%).

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Lead researcher Dr Paul Dolman, from UEA’s school of Environmental Sciences, said: “Deer management is often based on guesswork. This is the first time that a population has been quantified and studied in terms of how the deer are breeding - to measure the effectiveness of deer management.

Dr Kristin Wäber, who conducted the study while a PhD student at UEA, said: “Native deer are an important part of our wildlife that add beauty and excitement to the countryside, but left unchecked they threaten our woodland biodiversity. Trying to control deer without a robust understanding of their true numbers can be like sleepwalking into disaster. To effectively reduce and stabilise the population establishing numbers is vital.

“In Thetford Forest, despite an active programme of professional management culling thousand of deer, the numbers culled did not offset productivity. It is likely that this is happening in other landscapes across much of England. This is a particular problem for non-native invasive species like muntjac.

“In recent years people have become more and more concerned about the impacts deer are having in North America, Britain and elsewhere in Europe. Increasing deer populations are a serious threat to biodiversity – particularly impacting on woodland birds such as migrant warblers and the nightingale.

“They also carry diseases such as Lymes, and if numbers are not properly managed, they can cause damage to crops as well as road traffic accidents. To help control carbon emissions the government has set targets to increase woodfuel production, but this will be hard to achieve when woodlands are under so much pressure from deer.

“Current approaches to deer management are failing to contain the problem – often because numbers are being underestimated. Cull targets are often too low. This research shows that an annual cull of 53% for muntjac and 60 for roe deer is necessary to curb their continuing increase and spread.”

A Country Land and Business Association spokesman said: “The deer population in large areas of England is higher than the natural environment can support, leading to damage to woodlands and agricultural crops. The excellent research by the University of East Anglia in the east of England has confirmed our belief that the current cull numbers are not enough even to retain deer numbers at existing levels let alone reduce the population to a level where it stops impacting adversely on the natural environment.

“Woodlands are also under attack from a large number of insect pests and tree diseases such as Chalara, many of which are impossible to control. Therefore, it is even more important that we start effective management of threats such as deer and grey squirrels where we could have a beneficial effect.

“Even in areas such as Wales, where deer are not yet a major threat to the natural environment, the experience from the east of England is that it is much easier to take action early when the numbers are low than it is to try to reduce them when they have increased to the level that they are causing significant damage.”

‘Achieving Landscape-Scale Deer Management for Biodiversity Conservation: The Need to Consider Sources and Links’ by K. Waber, P. Dolman (both UEA) and J. Spencer (Forestry Commission) is published in the Journal of Wildlife Management March 7, 2013.