Innovative camera trapping technique provides insight into small mammal population

Camera trap

“Our technique provides a low-cost survey method for small mammals that is labour-efficient and has minimal animal welfare implications. The approach is a relatively simple and low-tech solution that can be used with a broad range of widely used camera traps”

Small mammals, such as mice and shrews, can occur in large numbers and play a crucial role in ecosystem functioning. They can drive predator populations and generate cascading effects on many prey species. They are also difficult to survey due to their size and largely nocturnal behaviour. However, utilising an innovative camera trapping technique a study, including scientists from the James Hutton Institute, has captured valuable data on these small creatures.

Camera traps have become an increasingly common tool for wildlife surveillance and monitoring. However, despite increased functionality, small mammals have continued to present many challenges in camera trap surveys. Their size is often insufficient to trigger the camera’s infra-red sensor, whilst images that are captured may be of inadequate quality for species identification.

The conventional survey method for small mammals, live trapping, can be both labour-intensive and detrimental to animal welfare. In collaboration with colleagues at the RSPB, Mammal Society and SRUC, researchers at the Institute have demonstrated that by adapting existing camera traps, small mammal data can be collected effectively without the need for live trapping.

The study shows how a standard and widely used model/type of camera trap (Bushnell Trophy Camera Traps) can be modified by fitting a close-focus lens, reducing the flash intensity to prevent over-illumination and fixing to cheap and easily constructed baited tunnels, to successfully record the presence of a range of small (and not so small) mammals. Video was captured instead of still image (traditionally used in larger mammal monitoring), as researchers believed this would increase the chance of species being identified effectively.

Scott Newey a Population Ecologist at the James Hutton Institute said: “Small mammals are really fascinating and an important component of many ecosystems, but often under-recorded. The method we developed adds another tool to the ecologist’s tool kit”.

To demonstrate the use of the technique researchers deployed modified camera traps in a peatland landscape in different stages of restoration, including plantation forestry (planted on drained former blanket bog), ex-forestry areas undergoing bog restoration and on unmodified blanket bog habitat. Monitoring entailed 108 individual camera trap deployments, each over two nights and one day.

Over this time, the cameras captured 3,071 videos depicting animals. More than half were in plantations, around one third were in restoration areas and the fewest were in undamaged bog. Five small mammal species were recorded: wood mouse, bank vole, field vole, common shrew and pygmy shrew. Mice and voles were detected only in forestry and restoration areas, whilst shrews were detected across all habitat.

Nick Littlewood, lead author of the study and an Honorary Research Associate with the James Hutton Institute, said: “Our technique provides a low-cost survey method for small mammals that is labour-efficient and has minimal animal welfare implications. The approach is a relatively simple and low-tech solution that can be used with a broad range of widely used camera traps.”

Co-author, Rose Toney, added “Lots of people now use camera traps to record wildlife and this method is an easy way to increase the range of species that camera traps can be used to monitor”.

The full study can be found here.

Notes to editors

The project also included input from the University of Cambridge and the North East Scotland Biodiversity Partnership.