Located in County Mayo, Lough Mask is situated south of Lough Carra (site 049), which drains into it, and north of Lough Corrib (site 056), into which it drains. It is one of the deepest lakes in the country and is calcareous. It is fed by the Owenbrin river which deposits large amounts of sandy sediment at its entrance forming an extensive delta.
The site was designated as a Special Protection Area on the basis of its migratory waterfowl populations, with Aythya fuligula occurring in numbers of national importance (684 birds, 1996). There are also nationally important colonies of breeding gulls, with Larus fuscus (722 birds, 1993), L. canus (742 birds, 1993) and L. ridibundus (2,650 birds, 1993). It is also a probable breeding site for the nationally scarce Melanitta nigra.
BirdLife International (2020) Important Bird Areas factsheet: Lough Mask. Downloaded from http://www.birdlife.org on 12/08/2020.