Appeal for help on deer and disease risks

Much like the rest of the Northern hemisphere, deer populations are expanding throughout the UK and Ireland; by as much as double in the UK since the turn of the century and 4-fold in Ireland in the same period (according to the Deer Initiative and hunting statistics, respectively).

Friday, 2nd July 2021, 8:39 am

It is estimated that the current number of wild deer in the UK totals over 2 million.

While these are undoubtedly beautiful animals, that many people hold ‘deer’ (sorry!) to their hearts, deer in the UK and Ireland have no natural predators, and, left unchecked, ‘breed more rapidly than necessary to simply sustain their populations’ (British Deer Society). This makes continued population increase almost inevitable.

Know your deer: how to tell the main species apart

In the UK and Ireland, our main species of deer are; Red, Fallow, Sika and Roe (notably absent on the island of Ireland), Muntjac and hybrid deer species are also known to inhabit some regions. Each of these species have their own physical and behavioral characteristics, as well as dietary and habitat preferences. Red deer are the largest UK land mammal, weighing up to 190kg, with a red-brown coat and a cream coloured rump. Male antlers start with two prongs and are shed every year; in older bucks they can eventually develop up to sixteen pongs. Fallow deer weigh up to 93kg, usually have a light chestnut-brown coat with white spots in summer, a duller grey-brown coat in winter, and a black, horse-shoe shape on their rump. Bucks have broad, palmate antlers, that shed and regrow more elaborately every year. All-black and all-white coat Fallows also occur. Sika are medium sized; up to one meter tall, with a small head and a worried-looking furrowed brow. Their coats are yellow-brown with white spots and a white rump in summer, and they possess a short, white tail. Roe are up to 25kg with a bright rusty red coat in summer, dull grey in winter. Both sexes have a white rump, no tail, large ears and their facial features are highlighted by white areas. Bucks have three-pronged, velvety textured, knobbly antlers. Muntjac are small at just 10 to 18kg. Their rumps are higher than their shoulders and their coats are russet brown, grey in winter, and they have a wide, flat tail with a white underside. While males have black, vertical stripes down their faces, females have a dark ‘crown’. Bucks have small, inwardly curved, non-branching antlers.

How might deer population increases affect livestock?

So what’s the concern about population growth in animals that evoke associative words like ‘majestic’ or memories of Disney’s Bambi? Unfortunately, there are disadvantages to having too many large bodied mammals roaming the countryside. Most deer species can be destructive to forestry and commercial and agricultural crops, uprooting naïve shoots for food, trampling grounds and damaging trees with antler gouging. They are also implicated in a large number of road traffic accidents each year, causing damage to vehicles and injury or even death to both themselves and motorists.

Deer also share some diseases with livestock, including epidemic diseases like Foot and Mouth Disease, and those already present such as bovine tuberculosis. The place of deer in the epidemiology of livestock diseases is likely to be complex and there is currently no evidence that they are important reservoirs or sources of livestock disease in the UK and Ireland. However, it is worth knowing which infections they can and can’t carry, including those as yet unstudied. For example, it has been established that the viruses responsible for Bovine Viral Diarrhoea (BVD) and Infectious Bovine Rhinotracheitis (IBR) can also infect some deer species. The animal welfare and economic consequences of these two diseases in livestock are substantial, and there is a need for more information on whether viral persistence in deer might affect disease control and eradication efforts.

Help us to find out more

As part of my PhD in biological sciences, I am exploring the association between deer and diseases pathogenic in livestock, focusing on BVD and IBR.

To help us close some of the current knowledge gaps, we would like to know more about observations of deer on farmland. If you’d like to help, you can access a brief survey at: