The word ‘sika’ in Japanese, where this deer species is originally from, means ‘deer’ and hence why this species is only referred to as ‘sika’ rather than ‘sika deer’. Four sika from Japan were imported, in 1860, first to Lord Powerscourt’s Demense in Wicklow, and subsequently three (one male, two females) from Powerscourt’s estate were sent to the Lord Kenmare’s Muckross estate in Co. Kerry in 1865.
The summer coats of adult sika are a light-reddish brown colours with white spots. Sika have a dorsal black stripe, which is prominent in both summer and winter coats, which runs from the back of the head to the tail. They also have a black-bordered white rump patch. The winter coats are darker and coarser and without the white spots.
The antlers, which are only borne by the males of the deer species and are shed annually in late Spring and subsequently regrown, are of a number of points (usually eight). The antler form and size can vary considerably with age and condition of the male and the number of points on each antler does not directly correlate with age (years) of the deer.
The typical life span of a wild deer is between 10 and 15 years of age, though exceptions can occur especially in deer parks and captive deer herds. The highest mortality period is in their first year of life, with over 80% of deaths occurring within the first week of birth. Females and males become reproductively mature at about 18 months of age, but are socially mature at different ages: females must attain a minimum body weight threshold before they can successfully conceive and produce a calf, usually two and a half years and older. On the other hand, males have a much slower growth rate and only reach their full adult body size/weight from the age of five years and can begin to successful fight and defend territories at that age.
Habitat and Foraging
Sika are predominantly grazers but can be classified as intermediate grazer-browsers due to their highly opportunistic feeding patterns. Sika will feed on grasses, broadleaf buds and twigs, heather, fruits, fungi and acorns. They can readily adapt to sparse conditions found in conifer plantations. This allows them to flourish in areas of pine forests, sitka spruce and larch stands.
Outside of the mating season, males can be found in small bachelor groups whereas females and their offspring (making up family units) live and eat in different ranges to the males. Adult males and females only come together to mate during the rut, which occurs during the months of September. The rut generally last for approximately 6 weeks. The males are very vocal during this time, attracting females and deterring males from their territories. Male deer can become highly aggressive during this time and will lash out at vegetation with their antlers, causing bark damage to young trees, branches and shrubs. It is very unwise to approach male deer during the rut as they may perceive a human observer as a threat to their territory. Sika males have a high pitched scream and whistle call. Adult males fight each other by locking their antlers and pushing their opponent while twisting the head. Serious injury and possible death can result from males fighting each other during the rut. The males do not eat very much during the rut as their primary concern is defence and mating with females. They can lose up to 20% of their total body weight during this period. Older aged males that are weakened from the rut, or have suffered injuries sustained during fighting bouts, may die during the following winter months.
The offspring, usually single births of a calf, are born in May/June. The calfs are born with a dappled spotty coat that helps camouflage them from predators such as foxes while their mother is away feeding. These are not abandoned, so please do not pick the calf up if found during this time. The offspring are weaned from their mother’s milk between seven and nine months of age.
Sika Deer are protected under the Wildlife Act (1976) and Wildlife (Amendment) Acts (2000).
Red deer and sika can interbreed and produce fertile hybrid offspring. At present hybrids are found in Co. Wicklow and surrounding areas, where the Wicklow population has expanded. A significant concern is the potential hybridisation between sika and red deer in the Kerry region given that the Kerry red deer are direct descendants of a Neolithic introduction from Britain. Equally of concern is potential interbreeding of the pure Kerry red deer with other red deer (of mixed/other stock), as well as the expansion of hybrid deer from the eastern region of Ireland to the southwest region, and such effects will threaten the pure genetic integrity of the Kerry red deer population. Overshooting may also be an additional concern for this particular population that is of significance within an Irish context.