Sound as a tool in the study of small mammals.

Barn Owl diet includes an array of small mammals, including Brown Rats and various species of mice and voles. Their abundance or otherwise affects survival and breeding success in the species, along with populations of other predators of small mammals. Photo ©Paul Sterry/Nature Photographers Ltd.

Small mammals are a challenge to study but a new approach is being pioneered by a team of scientists, including lead researcher Dr Stuart Newson of the British Trust for Ornithology. Their novel method monitors the vocalisations of Britain's mice, voles, shrews, rats and dormice. The team has developed a system of 'acoustic classifiers', which can be used to reveal the presence of different small mammal species in recordings made by automatic recording devices left in the field. This approach could be particularly valuable for determining the presence of different small mammal species on nature reserves or at sites where development is being planned.

Right: Being nocturnal and wary, Hazel Dormice are notoriously hard to study. Traditionally, ‘signs’ such as shredded honeysuckle bark and nibbled hazelnuts have provided indications of their presence. Hopefully, the use of sound as a way of detecting the species will improve the odds of discovering Hazel Dormice in locations where, for example, their habitats are threatened by development. Photo ©Paul Sterry/Nature Photographers Ltd.

Dr Newson commented "Our approach complements existing monitoring approaches for small mammals, adding data from many more locations for a suite of species whose status information is difficult to obtain and, in many cases, is lacking or not up to date. The collection of acoustic data for small mammals could be extremely cost-effective; small mammals often vocalise at night and their calls are often collected as 'by-catch' by those surveying bats. By running these recordings through the BTO's acoustic pipeline, small mammal calls can be detected, and the species identified. This approach could help conservation efforts by providing an economical and robust method for detecting the presence and abundance of small mammals, such as Hazel Dormice in woodland or introduced Brown Rats on seabird islands."

Right: Superficially similar to a Wood Mouse when seen fleetingly, the Yellow-necked Mouse is its larger cousin. Hopefully, vocalisation differences will help differentiate the two in the field, and identify their presence without the need for capturing the animals. Photo ©Paul Sterry/Nature Photographers Ltd.

For more information, read the following article: British Wildlife. Newson, S., Middleton, N. & Pearce, H. (2020). The acoustic identification of small terrestrial mammals in Britain. British Wildlife 32(3): 186–194. 

The sound files that make up the library can be accessed via: http://www.bto.org/small-mammals