Camera trap grey squirrel photograph data

Effective wildlife population management requires an understanding of the abundance of the target species. In the UK, the increase in numbers and range of the non-native invasive grey squirrel Sciurus carolinensis poses a substantial threat to the existence of the native red squirrel S. vulgaris, to tree health, and to the forestry industry. Reducing the number of grey squirrels is crucial to mitigate their impacts. 
Camera traps are increasingly used to estimate animal abundance, and methods have been developed that do not require the identification of individual animals. Most of these methods have been focussed on medium to large mammal species with large range sizes and may be unsuitable for measuring local abundances of smaller mammals that have variable detection rates and hard-to-measure movement behaviour.
The aim of this study was to develop a practical and cost-effective method, based on a camera trap index, that could be used by practitioners to estimate target densities of gr..., Study sites
The study was conducted in 10 mature woods at the same time of year, between mid-June and mid-July, from 2018 to 2021 (Table 1). Woods were located in two regions of the UK; eight in Yorkshire, England (54°N, 0°W) and two in Denbighshire, Wales (53°N, -3°W). Woods were between 6 ha and 28 ha in area and consisted of either broadleaf or a mix of broadleaf and conifer trees.  The area of each wood was measured from a satellite base map using a measure tool (Google My Maps 2018 to 2021). During the study, each wood was sampled once. To ensure independence, woods sampled within consecutive years were not directly connected to each other via wooded corridors or hedgerows and were located at least 600 metres apart. The first seven woods, sampled in 2018 and 2019, were discrete areas of woodland with little connectivity to other woodland areas. The last three woods sampled were highly connected to other woodland areas.
Camera deployment
At each wood, camera traps (Reconyx™ HC500 or..., Microsoft Excel