The Sika deer is one of three oriental species of deer now established in the UK following deliberate introduction and/or escape from private collections. There are currently thought to be two races of Sika in Britain; a larger-bodied race that originated from mainland Asia and Taiwan and a smaller-bodied race from Japan. Sika are considered an invasive species in Britain owing to the problems they cause to forestry interests and their ability to hybridise with native Red deer.
That which follows is a brief summary of Sika deer natural history. The detailed article for this species will follow in due course. Certain aspects of the natural history common to all deer (e.g. antler growth and formation, collisions with vehicles, chronic wasting disease) have been split from the individual overviews and placed into their own Q/A - this is partly to avoid repetition but also to allow more detailed coverage of the topics. A summary of the more general aspects of the biology, ecology and behaviour of Britain’s deer species can be found in the Deer Overview.
The Japanese Sika deer at a glance
Size: Adults 1.14 m to 1.7 m (5.5 ft) long; stag (male) stands 80 to 90 cm (3 ft) at shoulder. Adult males average 64 kg (140 lbs.), females 41 kg (90 lbs.), and newborn calf weighs ca. 3 kg (7 lbs.). Females (hinds) slightly smaller than stags. Size highly variable in accordance with habitat quality.
Colour: Two moults per year leading to red-brown coat with white spots (all ages) in summer and grey-brown or black coat (with less distinct or absent spots) in winter. White rumps with black stripe down tail and brown border; white metatarsal glands on hock. Antlers similar to Red deer, although smoother texture and max. 4 tines per antler - single front-pointing tine on each antler.
Sexing: As with most species, the males sport antlers for much of the year and tend to be larger and more muscular than females. Males are “stags”, females “hinds” and young are “calves”.
Distribution: Introduced from Japan some time ca. 1860. Now scattered populations across UK, including England, Scotland and Ireland - largest populations in Scottish Highlands. Absent from much of England and Wales. Population estimated at ca. 35,000; thought to be increasing at ca. 5.3% per year. Outside of UK, scattered populations in Europe (e.g. German, France and Czech Republic) - native range is Japan and South-east Asia.
Longevity: In wild reach 8 to 10 yrs, exceptional ages of 15 yrs known.
Sexing: Males have antlers for much of year (shed in spring), laryngeal prominence (Adam's apple) and penis sheath.
Antler Cycle: Antlers cast late March to late May (peak in April); velvet shed during August.
Activity: Active throughout day and night, with peak at dawn and dusk. Much time spent in woodland and surrounding grassland.
Habitat: Areas of mixed or deciduous woodland and grassy open spaces with shrubby undergrowth for shelter and feeding. Can be found in open conifer stands and parks.
Territory: Non-territorial. Prepare for rut late September; maintain rutting stands between hind resting and feeding sites - rut runs during October and November. Stags can range over 40 to 60 ha (100 - 150 acres) depending on age (will tolerate subordinates on territory); hinds range less - 18 to 22 ha (45 - 54 acres).
Diet: Primarily grazes grasses, herbs, and sedges, although will browse for leaves, shoots and ivy; bark, shrubs, fruits, berries and fungi taken according to season.
Reproduction: Rut early October to early November (peak around 20th October). Single (twins very rare) calf born after roughly 8 month gestation (bulk during May and June). Calf suckled for 6 to 10 months; stays with hind for first year and is sexually mature at about 16 months old. Rutting call is a protracted “whistle” - click below to listen.
A Sika deer (Cervus nippon) stag whistling during the rut in the UK - Credit: Marc Baldwin
Behaviour and Sociality: During late spring and summer (i.e. outside of rutting season), hinds may live in small social groups with calves, although in some areas (e.g. New Forest) majority seen either solitarily or with single calf; stags live either solitarily or in small bachelor groups. Mixed sex groups of adults established during rut and can persist until hinds leave to calve in spring.
Threats: Hunted for sport in parts of their range; generally shot by stalkers. Controlled in areas with peripheral populations of Red deer - Red and Sika can hybridise to produce fertile offspring, thus diluting the “pure-blood” Red gene pool. Roads can pose threat to deer; people often killed or seriously injured upon collision with deer. Sometimes come into conflict with forestry or private land owners because of the damage they can do to trees (esp. bark stripping in commercial plantations).
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