The willow grouse (Lagopus lagopus) has a circumpolar distribution from Canada to Russia, including Britain and Ireland. British and Irish grouse are considered distinct from the typical willow grouse based on plumage characteristics. For example British grouse do not change colour between seasons, unlike the willow grouse, thus they are taxonomically classified as separate subspecies (Lagopus l. scoticus).

Its habitat within the UK includes blanket bogs, raised bogs and heath. Although the status of this population as a subspecies is generally well accepted, a more controversial question relates to the Irish population of red grouse. Whether or not the Irish population of grouse is taxonomically distinct from the British population was one of the issues address in the genetic research conducted by the trust.

The Irish race is paler in plumage colouration (almost yellow) due a higher proportion of grasses and sedges in Irish moor land habitats. The red grouse is one of only two remaining resident native species of Galliforme in Ireland, the other being the grey partridge (Perdix perdix).

A third species of Galliforme quail (Coturnix coturnix), is a species that breeds in Ireland and overwinters in Africa. All of these species are red listed species of conservation concern in Ireland (Newton et al 1999).