 Temperatures fell as low as −17.2 °C (1 °F) in County Mayo on 20 December and up to a metre (3 ft) of snow fell in mountainous areas.Because Ireland became isolated from mainland Europe by rising sea levels before the last ice age had completely finished, it has fewer land animal and plant species than Great Britain or mainland Europe.There are 55 mammal species in Ireland, and of them only 26 land mammal species are considered native to Ireland.