Reviewing Deer in Britain for Invasive Species Week – 16th -22nd May 2022
Deer get a mixed press – they are simultaneously loved and disliked. People love to watch them as beautiful or majestic mammals, some are easily seen and others can be elusive so an exciting challenge to find. They are hunted (and poached); venison is a popular and healthy meat and they can bring big economic gains such as stalking in the Highlands. However, deer can also have a serious negative impact causing damage to crops, forests, nature conservation and causing a high number road traffic accidents with implications for human health. All deer bring benefits and all deer can have negative economic and environment costs.
There are six species of deer in Britain and the Mammal Society’s 2018 status review confirms that all deer have increased in population size and geographical range in the last 20 years, making them among the most successful British mammals. Lack of any natural predators has enabled deer to expand. Some argue that predators such as Lynx and wolf should be reintroduced (both having become extinct due to hunting) should be reintroduced to assist with deer management.
Only two deer are native, Red deer (Cervus elaphus) and Roe deer (Capreolus capreolus). Four deer are invasive non-native species. This means they have been moved from their country of origin (as their name often suggests) and brought into Britain by humans. It also means they have a negative impact on the environment, the economy and human health. (There are around 2000 non-native species in Britain, but these species do not have negative impacts).
These four invasive non-native deer were brought into Britain at different times, have different impacts and different geographical ranges:
Fallow deer (Dama dama) were deliberately released into the wild for hunting by the Normans and are fairly widespread across Britain. Woodland habitat can be significantly impacted and they are frequently involved in road traffic accidents.
Sika deer (Cervus nippon) have been present in Britain since 1860 and have a patchy but expanding distribution across Britain. (These deer are not common in the South West where I live; I have mixed feelings about wanting to see one down here). Sika deer can cause damage to forestry and crops but also have a negative impact through hybridisation with the native red deer.
Muntjac deer (Muntiacus reevesi), also known as Reeves’ muntjac, were deliberate or accidental releases after being brought here for private collections in the 1830s. It has a patchy presence in Britain, being more common in England, sparse in Wales and with only a few records in Scotland. It has impacts on biodiversity, forestry and can be involved in road traffic accidents (I’ve only ever seen Muntjac on the road – all dead but one racing across the road).
Chinese water deer (Hydropotes inermis) became established in the wild in the 1940s from private collections. The population is predominantly limited to the east of England but has shown some expansion and show a preference for wetland habitats, e.g. along rivers or reedbeds. (I’ve never seen a CWD, but would love to see this strange looking deer). Britain forms a high proportion of the global total as they are declining in their native countries. Chinese water deer can cause damage to agricultural crops.
Throughout the week will be sharing daily blogs on all six deer, their status, impact, management and how to identify them. The aim of Invasive Species Week is to raise awareness and encourage reporting. We want to encourage sharing records of all six species of deer. We don’t just want records made during Invasive Species Week, but any historical records you have hiding in old journals or stored on your computer. You can email, post or use Mammal Mapper. By getting a better understanding of deer distribution, we are better placed to advise on conservation needs.
Article by Kate Hills, a founding member of the Cornwall and Devon Mammal Groups and former Vice Chair of the Mammal Society and Local Groups Committee chair. She retired from Council in April 2022, but remains involved with the Local Groups Committee. Her day job is as the Biosecurity and Invasives Manager at South West Water. Talking about invasive mammals combines two passions!