Muntjac are in Ireland, north and south of the border. It is thought they were deliberatley introduced for shooting / sporting reasons, though whoever did this has opened a serious can of worms. They were introduced to Woburn Park, Bedfordshire in 1838.
Muntjac are very destructive, eat just about whatever is in there path, can breed a couple of times a year and often have a calf at foot. So that along with the fact that they are more solitary in habit can make selecting the right animal for culling quite difficult. The herd size in England is around 60,000, but that increases 10% annually, far more than any other deer species. They are serious habitat destroyers and grazers, particularly in forestry, market gardening / veg growing and coppice re-growth / young trees. They cause around £10 million of damage to the east of England alone.
It is estimated that the uk national herd will have doubled in size by 2015, and they will soon take over the Fallow as the 3rd most common deer in the uk. They compete with the Roe deer in this country, with the Roe often coming off second best and being pushed out of it's territory.
I belive there are pretty hefty fines in place for deliberate introduction, but obviously it's a bit late for that now, so now you guys in Ireland need to get shooting them before they take over!
Though they do not physically compete with 'native' species, it's food, fertility and breeding that often leads to the natives coming off worst, though they havn't made serious inroads into Red territory in the uk as one thing they hate is the cold. In really cold winters, like last year, there are higher than normal mortality rates among Muntjac.
