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Mice and Wrens

St Kilda Mice

Two kinds of mice used to be found on St Kilda. Both were varieties (subspecies) of the mainland house mouse and wood mouse respectively. They were probably brought to St Kilda by Norsemen. Like many animals which have become isolated, they evolved to be different from their ancestors, in this case larger.

St Kilda Field Mouse
Photograph: National Trust for Scotland

The St Kilda house mouse was dependent on the presence of people, as it fed on grain and other human commodities. With the evacuation of the people in 1930, its source of food was lost and it died out. It is now extinct and only exists as specimens in museum collections.

The St Kilda field mouse is still common on Hirta and is also present on Dun. It was never so dependent on people, so it did not die out like the house mouse. It feeds on snails, insects, moss and seeds, but will also feed on the carcasses of dead sheep, birds and any apples, Mars bars or other delicacies foolishly left around by work party members!


St Kilda Wren

The St Kilda wren is a sub-species of the mainland wren and has only been found on Hirta, Dun, Soay and Boreray. It is larger than those from the mainland.

A male wren proclaiming his territory in the Village
Photograph: Glasgow Museums

Recording courtesy of The British Library National Sound Archive

Altogether there are only a few hundred pairs, making it a great rarity. Specimens of the adult birds and their eggs were highly prized. The St Kildans used to collect eggs for selling to collectors. Today it is fully protected on St Kilda.

In recent years the islands' summer warden has been plotting the distribution of St Kilda wrens. The most recent census was done on Hirta in 1993. A total of 113 - 117 pairs were recorded. A map showing apparent occupied territories was produced. Territories were based on areas where males were recorded singing at least three times, a nest or young were found, or where a bird was giving an alarm call.

© The National Trust for Scotland