Primarily nocturnal or crepuscular, the sika deer can also sometimes be seen foraging during the day, grazing singly or in small herds. The sika deer is not a particularly gregarious species, and adult males tend to be solitary for most of the year, only gathering together once their antlers have been shed. Male and female sika deer occupy different areas for most of the year, and only come together during the mating season. Sika deer do not migrate large distances between summer and winter, but this species is known to migrate to lower valleys in the winter. Interestingly, the sika deer is a good swimmer, and is also capable of jumping over objects up to 1.7 metres in height.
The sika deer is a herbivorous species, feeding on many different plants including grasses, browse and even fruit. In the summer, this species’ diet tends to consist primarily of grasses and herbs, whereas in winter months more woody plants are consumed. The shoots and bark of coniferous trees may sometimes be taken, and the sika deer has been reported to feed on crops in the spring and early summer.
As in other deer, male sika deer rub their antlers against trees both to remove velvet and as a territory marker. The antlers are cast in May, and grow throughout the summer. The breeding season of the sika deer, known as the rut, typically occurs in the autumn, from about September to November or December. Males establish and defend territories, using their forefeet and antlers to dig holes up to 1.6 metres wide and 0.3 metres deep in which they frequently urinate to signal territory boundaries. Fierce fighting often occurs between rival males, who all try to drive available females into their territories where mating takes place. Successful male sika deer may mate with as many as 12 females, and may be so intent on finding females that they do not feed until later on in the rutting season.
The gestation period of the sika deer is around 30 weeks, after which time the female gives birth to a single calf, rarely two. The timing of birth varies slightly with geographic location, but young are typically born between April and July, mostly in May and June. Young sika deer grow rapidly, and are weaned by late summer, approaching the weight of the mother by eight months of age. Female sika deer may be sexually mature at six months of age, and tend to first breed as yearlings. The sika deer has been reported to live for up to 12 years in the wild, but individuals in captivity have been known to reach 25 years old.
The sika deer (Cervus nippon) is a relatively small deer, although there is considerable variation in size between its numerous subspecies. In the summer months, its coat is mainly reddish- to yellowish-brown, with a dark line running down the centre of its back from head to rump and numerous white spots patterning its body. In the winter months, the coat of the sika deer generally becomes greyer, with males turning dark grey to black and females turning light brown to grey, and the white spots become far less conspicuous. The underparts of the sika deer are whitish or grey, and there is a large, white, heart-shaped patch across the rump and tail which is edged with black. A thin, dark line also runs down the white tail.
Male sika deer, known as stags, are much larger than the females, and can be distinguished by the presence of antlers which are narrow and branched, usually with between two and five points or ‘tines’. These antlers typically reach between 30 and 66 centimetres in height. A pronounced V-shaped mark can be seen on the brow of the male sika deer, and distinct white glands are visible on the lower hind legs.
The sika deer produces a wide range of vocalisations, which are typically most noticeable during the mating season. During this time, known as the ‘rut’, males make long, drawn-out whistling cries which are said to sound like a siren and can become more scream-like as the rut progresses. Stags are also known to produce groans and raspberry-blowing sounds, while female sika deer use a goat-like bleat to contact their young. When alarmed, sika deer produce a short, high-pitched bark. There are several recognised subspecies of sika deer, although there is some disagreement about how many.
The sika deer can be active throughout the day, though in areas with heavy human disturbance, they tend to be nocturnal. Seasonal migration is known to occur in mountainous areas, such as Japan, with winter ranges being up to 700 metres (2,300 ft) lower in elevation than summer ranges.
Lifestyles vary between individuals, with some occurring alone while others are found in single-sex groups. Large herds will gather in autumn and winter. The sika deer is a highly vocal species, with over 10 individual sounds, ranging from soft whistles to loud screams.
Sika males are territorial and keep harems of females during the rut, which peaks from early September through October, but may last well into the winter months. Territory size varies with habitat type and size of the buck; strong, prime bucks may hold up to 2 hectares (5 acres). Territories are marked with a series of shallow pits or "scrapes", into which the males urinate and from which emanates a strong, musky odor. Fights between rival males are sometimes fierce and long, and may even be fatal.
The gestation period lasts for 7 months. Hinds give birth to a single fawn, weighing 4.5 to 7 kilograms (9.9 to 15.4 lb), which is nursed for up to 10 months. The fawn becomes independent 10 to 12 months after birth, and attains sexual maturity at 16 to 18 months in both sexes. The sika deer may interbreed with the Red Deer; hybrid descendants may have adaptive advantages over purebred relatives. The average lifespan is 15 to 18 years in captivity, although one case is recorded as living 25 years and 5 months.
InNara Prefecture, Japan, the deer are also known as "bowing deer", as they bow their heads before being fed specialshika senbei(鹿せんべい?, called "deer cookies"). However, deer bow heads to signal that they are about to headbutt. Therefore, when a human 'bows' to a deer, the deer will assume the same stance and may charge and injure the human. Deer headbutt both for play and to assert dominance, as do goats. Sika deer are found throughout thecity of Naraand its many parks and temples likeTōdai-ji, as they are considered to be the messengers of theShintogods.
The sika deer is native to Japan, China, Taiwan and other adjacent regions of the eastern Asian mainland, including south-eastern Siberia. Although once found in both the Republic of Korea and the People’s Democratic Republic of Korea, the sika deer is known to be regionally extinct in the former, and potentially extinct in the latter. There are several subspecies of sika deer, which all have different distributions.
The sika deer has also been widely introduced to countries outside of its natural range, including Austria, Denmark, Germany, New Zealand, the United Kingdom and the United States. This species was first introduced to the United Kingdom in 1860 when it was released into deer parks, and has since become established in the wild following escapes or deliberate release. The sika deer increased its distribution on the British mainland by 5.3 percent per year between 1972 and 2002, and continues to expand its range in Scotland, as well as in many other countries to which it was introduced.
Showing a preference for habitats with acidic soil, the sika deer can be found in a variety of habitats including heath, coniferous forests and plantations. This species tends to be found in forests with a dense understorey, but is known to forage in grassy areas and in dense woody thickets along the borders of freshwater or brackish marshes. In its introduced range within the United Kingdom, the sika deer occupies a range of habitats, including mature broadleaf woodland, bogs, saltmarshes and offshore islands.
Across its original range and in many areas to which it has been introduced, the sika is regarded as a particularly prized and elusive sportsman's quarry. In Britain, Ireland, and mainland Europe, sika display very different survival strategies and escape tactics from the indigenous deer. They have a marked tendency to use concealment in circumstances when red deer, for example, would flee, and have been seen to squat and lie belly-flat when danger threatens.
Hunters and control cullers have estimated that the sika's wariness and "cleverness" makes it three or four times more difficult to bring to bag than a red or fallow deer.In the British Isles, sika are widely regarded as a serious threat to new and established woodlands, and public and private forestry bodies adopt policies of rigorous year-round culling.