Use of a novel camera trapping approach to measure small mammal responses to peatland restoration

Nick A Littlewood,Rose Toney,Scott Newey,Mark H Hancock,Gorm Shackelford

doi:10.1007/s10344-020-01449-z

Abstract

Small mammals, such as small rodents (Rodentia: Muroidea) and shrews (Insectivora: Soricidae), present particular challenges in camera trap surveys. Their size is often insufficient to trigger infra-red sensors, whilst resultant images 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. Here, we describe a method for using camera traps for monitoring small mammals. We show that by attaching the camera trap to a baited tunnel, fixing a close-focus lens over the camera trap lens, and reducing the flash intensity, pictures or videos can be obtained of sufficient quality for identifying species. We demonstrate the use of the method by comparing occurrences of small mammals in a peatland landscape containing (i) plantation forestry (planted on drained former blanket bog), (ii) ex-forestry areas undergoing bog restoration, and (iii) unmodified blanket bog habitat. Rodents were detected only in forestry and restoration areas, whilst shrews were detected across all habitat. The odds of detecting small mammals were 7.6 times higher on camera traps set in plantation forestry than in unmodified bog, and 3.7 times higher on camera traps in restoration areas than in bog. When absolute abundance estimates are not required, and camera traps are available, this technique provides a low-cost survey method that is labour-efficient and has minimal animal welfare implications.

Highlights

With reduced costs and increased functionality, camera traps have become an increasingly common tool for wildlife surveillance and monitoring (e.g. Rovero and Zimmerman 2016)
In terms of ecosystem function as prey and as consumers with potential to cause economic damage (e.g. Ryszkowski 1975), relatively fewer studies have focussed on small mammals, such as shrews (Eulipotyphla: Soricidae) and small rodents (Rodentia)
Monitoring covered a total of 108 camera trap deployments (12 trap sets in each of three habitats, with three camera traps deployed for each trap set)

Summary

Introduction

With reduced costs and increased functionality, camera traps have become an increasingly common tool for wildlife surveillance and monitoring (e.g. Rovero and Zimmerman 2016). Camera traps are especially used for studying mammals, with the order Carnivora comprising by far the largest group within published studies (Agha et al 2018; McCallum 2013) Despite their importance, in terms of ecosystem function as prey and as consumers with potential to cause economic damage Small mammals often occur in high abundance and can have crucial roles in ecosystem functioning, such as by driving predator populations and generating cascading effects on other prey species (e.g. Bêty et al 2002). They can be difficult to survey, due to their small size and largely nocturnal behaviour.

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Discussion

Conclusion