Scotland's red deer are shrinking — and its imported Sika deer are getting larger:
Sika deer (Cervus nippon) occur in many of the habitats in Scotland that the native red deer (Cervus elaphus) lives.Although it was already known that sika crossbreed with red deer, it was thought the overall impact on the native species was low.
The two species differ greatly in appearance: red deer are larger than sika, usually standing 30cm taller at the shoulder.
Red deer stags can also grow antlers with 12 points or more but sika antlers rarely exceed eight points.
Despite the fact that sika are smaller in size, the two species can mate giving birth to hybrids that are fertile.
At present hybrids are a rare occurrence, with scientists estimating that between 0.01 to 0.02% of deer in most areas where the species overlap are hybrids.
However, it has been found that in some areas as many as 40% of deer are of mixed breed.
Such crossbreeding may permanently alter wild deer on Scotland’s mainland, some researchers fear.