There are three species of deer

Deer

Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...

 living wild in Ireland

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 today, namely Red Deer

Red Deer

The red deer is one of the largest deer species. Depending on taxonomy, the red deer inhabits most of Europe, the Caucasus Mountains region, Asia Minor, parts of western Asia, and central Asia. It also inhabits the Atlas Mountains region between Morocco and Tunisia in northwestern Africa, being...

, Fallow Deer

Fallow Deer

The Fallow Deer is a ruminant mammal belonging to the family Cervidae. This common species is native to western Eurasia, but has been introduced widely elsewhere. It often includes the rarer Persian Fallow Deer as a subspecies , while others treat it as an entirely different species The Fallow...

, and the Sika Deer

Sika Deer

The Sika Deer, Cervus nippon, also known as the Spotted Deer or the Japanese Deer, is a species of deer native to much of East Asia and introduced to various other parts of the world...

. Red deer have been in Ireland since the end of the ice age, but almost became extinct there, with only around 60 left, in the 20th century, but have now made a comeback to approximately one thousand. Fallow deer were introduced in Norman times, 1169 AD, and now have a population of about 10,000. Sika deer were introduced in Powerscourt

Powerscourt Estate

Powerscourt Estate , located near Enniskerry, County Wicklow, Ireland, is a large country estate which is noted for its house and landscaped gardens, today occupying 19 hectares . The house, originally a 13th century castle, was extensively altered during the 18th century by German architect...

 park in 1860, escaped from captivity, and now number about 20,000. A recent itroduction Reeves's Muntjac

Reeves's Muntjac

The Reeves' Muntjac is a muntjac species found widely in southeastern China and in Taiwan. They have also been introduced in the Netherlands, the United Kingdom and Ireland by 2008. It feeds on herbs, blossoms, succulent shoots, grasses and nuts, and was also reported to eat trees...

 is becoming established.

The Irish Elk

Irish Elk

The Irish Elk or Giant Deer , was a species of Megaloceros and one of the largest deer that ever lived. Its range extended across Eurasia, from Ireland to east of Lake Baikal, during the Late Pleistocene. The latest known remains of the species have been carbon dated to about 7,700 years ago...

became extinct in Ireland about 10,500 years ago, many of their skeletal remains have been found well preserved in peat land.