Invasive Alien Species in Northern Ireland

Cervus nippon, Sika Deer

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Cervus nippon
© Tom Ennis
Cervus nippon
© Tom Ennis
Cervus nippon
© Tom Ennis
Cervus nippon
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Cervus nippon Temminck, 1838
Sika deer are small to medium-sized deer originally from Japan. They were introduced into Ireland as decorative additions to the native deer in 1860 by Lord Powerscourt. The first sika deer arrived in Northern Ireland in 1870.
Sika deer prefer woodland habitat with plenty of cover, this can be either deciduous or coniferous.
Sika deer are slightly smaller than fallow deer, males can measure up to 85cm at the shoulder; females are slightly smaller. Coat colour varies from summer to winter. In summer the coat is a reddish chestnut with white or fawn spots and a pronounced dark stripe running along the spine. The winter coat varies from grey in females to almost black in males. Both sexes have a white, heart-shaped tail patch surrounded by darker hairs. When the deer is alarmed, the white hairs rise up and fan out making the white patch on its bottom much more noticeable. Other deer can see this patch easily and it acts as a danger signal.
The hock glands on the hind legs are surrounded by tufts of white hair making them very noticeable. Only males have antlers; these are shed in spring and a new set starts to develop immediately. The growing antlers are covered in velvet which dies when the antlers are fully grown and is then rubbed off.
Country of origin
Current distribution
Sika deer are found in Scotland and England. They are not present in Wales. In Europe they are found in a number of countries which include the Czech Republic, Denmark, Germany, Austria and Russia. They have also been introduced into New Zealand and the USA.
Location in Ireland
In Northern Ireland, Sika deer are found mainly in Fermanagh and Tyrone. In the Republic of Ireland the largest numbers are in Kerry and Wicklow, with smaller numbers in Dublin, Donegal, Carlow, Cork and Kildare.
Sika deer were introduced into Ireland in 1860 by Lord Powerscourt. A single male (stag) and three females (hinds) were released into his estate in County Wicklow. The sika bred with red deer already in the estate and within a few years the herd of sika and sika hybrids had increased so much that Lord Powerscourt was able to supply deer to other estates. Many deer escaped from the estate into surrounding woodland. From the 1940s onward, large areas of state forest were planted in the Republic of Ireland. This provided the deer with shelter and allowed them to spread over large areas of County Wicklow.
Sika were released near Killarney, County Kerry in 1865 by Lord Kenmare for hunting purposes. By 1948 there were around one thousand animals in the herd.
The first sika deer arrived in Northern Ireland in 1870 when a stag and five hinds were sent from Powerscourt to Colebrooke Park, County Fermanagh and twenty years later sika deer were sent from Colebrooke to Baronscourt, County Tyrone. In the 1920s, all the sika deer escaped from the deer park at Baronscourt and became established in the local woodland.
Life cycle
Sika deer are solitary for most of the year. In late autumn the rut takes place, when males fight amongst themselves to establish territories and gain access to females. Small mixed herds are formed after the rut, when mating takes place. Single calves are born in May and June. They have white spots at birt but these fade within a few months.
Sika deer prefer to spend the daytime in dense woodland and are rarely seen far from cover. At night they come out into the open to feed, mainly on grass and tree leaves.
Wildlife and habitat impacts
Sika deer are related to red deer and will interbreed with them. The hybrid offspring are fertile. Interbreeding would destroy the genetic purity of the native red deer as a species.
Sika deer can damage trees by gouging the trunks with their antlers and by bark stripping. They may prevent native woodland regeneration by browsing on young shoots and seedlings.
Human impacts
Sika can cause damage to commercial forestry plantations.
Key vectors
Sika deer were intentionally introduced into Ireland in 1860 as decorative additions to the native flora and for hunting purposes.
What you can do as an individual
Report sika deer sightings to CEDaR, Botany Department, Sciences Division, National Museums Northern Ireland, 153 Bangor Road, Cultra, Holywood, County Down BT18 0EU. Tel: 028 9039 5256, email[at]
Management measures
The Forest Service employs wildlife rangers who help to manage the wild herds of deer that live in their woodlands. This involves managing population numbers through a process of careful culling of the specific ages and sexes of animal required to keep the herd healthy and at sustainable levels. Forest design can also play an important part in the management of deer.
The protection and humane management of deer in Northern Ireland is governed by the Wildlife (Northern Ireland) Order 1985 S.I. No 171(N.1.2)
Further information
Invasive Species in Ireland
Northern Ireland's Mammals, Amphibians and Reptiles
Northern Ireland Forest Service
The British Deer Society
Hayden, T. and Harrington, R. (2000). Exploring Irish Mammals. Town House and Country House Ltd., Dublin.
See the Invasive Species Ireland web site for further information -
Text written by:
Angela Ross, Curator of Vertebrates, Ulster Museum