History of Scottish Gaelic
All surviving dialects are Highland and/or Hebridean dialects. Dialects of Lowland Gaelic have become defunct since the demise of Galwegian Gaelic, originally spoken in Galloway, which seems to have been the last Lowland dialect and which survived into the Modern Period. By the 18th century Lowland Gaelic had been largely replaced by Lowland Scots across much of Lowland Scotland. According to a reference in "The Carrick Covenanters " by James Crichton, the last place in the Lowlands where Scottish Gaelic was still spoken was the village of Barr in Carrick: only a few miles inland to the east of Girvan, but at one time very isolated. Crichton gives neither date nor details.
Scottish Gaelic
As with other Celtic languages, monolingualism is non-existent except among native-speaking children under school age in traditional areas. In 2014, the census of pupils in Scotland showed 497 pupils in publicly funded schools had Gaelic as the main language at home, a drop of 18% from 606 students in 2010. During the same period, Gaelic medium education in Scotland has grown, with 3,583 pupils being educated in a Gaelic-immersion environment in 2014, up from 2,638 pupils in 2009. However, even among pupils enrolled in Gaelic medium schools, 81% of primary students and 74% of secondary students report using English more often than Gaelic when speaking with their mothers at home.