The document is the earliest recorded list of the archipelago’s population and was discovered by archivists among a hoard of clan papers, the Belfast Telegraph reported.
The census lists 90 person living on the main island of Hirta on June 15, 1764 — 38 males and 52 females, including 19 families and nine individuals.
Shedding further light on the islanders’ diet, the report said each resident ate “36 wild fowls eggs and 18 fowls” daily — an island-wide total of 3,240 eggs and 1,620 birds every day.
The census report was discovered among the papers of Clan Maclachlan during cataloguing by the National Register of Archives for Scotland (NRAS), the branch of the National Records of Scotland which holds historical papers held in private hands.
Alison Rosie, NRAS registrar, said: “This document sheds new light on the history of St Kilda and the families who lived there, and gives us an insight into their lives more than 250 years ago.”
The archipelago is the largest seabird colony in the north-east Atlantic with 600,000 nesting birds each year.