The habits of some of St Kilda’s smallest inhabitants will soon be uncovered, as the University of Edinburgh begins a three-year study of the archipelago’s native field mouse.

The St Kilda Field Mouse is unique to the islands, which are owned and cared for by the National Trust for Scotland. Although field mice are common through the UK, the ones on St Kilda are unusual for several reasons, the most notable being that they are nearly twice the weight of their relatives on the mainland and have different hair colouration on their belly. They also live in unusual conditions, in that they have almost no predators on the islands and share the grass and herb food supply with only one other mammal, the diminutive Soay sheep.

Another subspecies of mouse unique to the islands, the St Kilda House Mouse, became extinct shortly after the evacuation of the archipelago in 1930.

While the St Kilda Field Mouse has been known about for many years, almost nothing is known about its numbers, habits or life cycle. The PhD study intends to uncover the manner in which these creatures live in order to understand how much they differ from mainland mice and to better conserve them in the future. Tom Black has been appointed to carry out the research and will travel to St Kilda in November to begin work on the mice.

The work is supported by the Natural Environment Research Council, the National Trust for Scotland and Scottish National Heritage.

Dr Richard Luxmoore, Senior Nature Conservation Adviser at the Trust, said: “We are particularly keen to find out about this little animal because we don’t want the same fate to befall it as its former neighbour. We need to know how many there are, where they live, what they eat and how they survive the winter on these seemingly inhospitable islands.”

Tom Black, the PhD student undertaking the research, said: “It is very exiting to have the opportunity to study a British mammal about which so little known. Being able to address so many questions about the ecology and evolution of these mice within a single study and in a location as incredible as St Kilda is a rare privilege.”