Britain’s biggest land animal and it’s ever growing population

Six species of deer exist in the UK, all differing in geographical distribution, abundance, population growth rate, behaviour, and impact. Only two, the red and roe deer, are considered a native species although the fallow deer is now generally consider part of our natural heritage having been introduced around the 11th century. Muntjac, Sika and Chinese water deer were all introduced within the last 150 years.

It is generally agreed amongst government agencies, NGOs and academics that deer are more abundant today than they have been since the last ice age. While it is difficult to assess deer numbers, due to their secretive nature and ability to roam across large areas, it is believed that there are roughly 2 million deer in the UK. Evidence for this population growth is found in their expansion of geographical range and an increase in deer impacts.

Why are there so many deer?

The rapid increase in deer population is due to a number of interacting environmental and ecological factors. Initially, numbers have increased due to escapes and releases from parks and farms. Milder winters, due to climate change, have favoured the deer allowing them to survive through the winter and spread to areas that would otherwise be unsuitable. An equally important factor in the deer’s expansion is changes in land use. The landscape has seen alterations in agriculture, with the planting of winter crops and an increase in woodland. With an increase conservation efforts there have also been a greater connectivity between green spaces in urban areas. There is little control over deer numbers with no natural predators in the UK, making human intervention important. Despite an estimated 350,000 deer culled every year and relatively high levels of road accident related deaths, current mortality rates are not high enough to halt the exploding population growth.

Research led by Dr Paul Dolman, ecologist at the University of East Anglia, suggests that current management techniques are failing. While the number of roe and muntjac deer in Breckland, East Anglia are stable, he believes it’s due to thousands of animals being pushed out into the surrounding countryside rather than successful management. The research proposes that 50% to 60% of deer would need to be killed in order to keep the numbers under control. This is far greater than the 20% to 30% previously recommended by the Deer Initiative (DI), a partnership dedicated to the delivery of a sustainable, well-managed wild deer population.

This research did however focus in on two species in one location and so cannot be applied to all the species across the whole of the UK. The RSPCA is opposed to the principle of culling and says they need very strong scientific evidence to support it. Along with the DI, they also believe that any decision to carry out a cull must be taken on a case by case basis and should reflect the ecology and environmental impacts rather than manmade ownership boundaries.

Why does managing deer matter?

Deer browse and graze, eating and considerably damaging woodlands and crops and threatening biodiversity. Dr Dolman explains that deer are noted as the major cause of unfavourable conditions in terms of woodland structure and regeneration. Deer damage young trees and coppice regrowth undermining efforts to establish and regenerate woodlands. At high densities deer can alter the structure and species composition of woodland vegetation which in turn can reduce the abundance of wild, and sometimes rare, flowering plants. This can also be detrimental to the growth of vertebrate and invertebrate fauna. Evidence suggests that deer reduce the number of woodland birds including the migratory birds Blackcaps and Nightingales. It has been suggested that biodiversity is likely to be greatest when there are low densities of deer, rather than high density or none at all.

As well as adverse impacts on woodland ecosystems there are a number of other economic costs such as damage to agriculture, the transfer of diseases and posing a direct threat to public safety through their involvement in road accidents. That said there are also economic benefits of deer, such as being a large part of the tourism industry, especially in Scotland.

What do you think? Is it our place to manage deer? How is the best way to go about it? Is there a more ethical and sustainable approach than culling?

For more on UK deer and the impact they have on the environment:

Deer Initiative

Deer: 50% cull ‘necessary to protect countryside’

Economic costs and benefits of wild deer and their management in Scotland

Economic impacts of wild deer in the east of England

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Abi Gardner

I'm a Ecosystem Services (MSc) student at The University of Edinburgh, with a background in Environmental Geography. I'm passionate about ecology, biogeography, environmental management, sustainability and climate change.

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