Date: 15 July 2026
Location: Southern Water Treatment Works, Winchester
Duration: 2.75 Hours
Habitat: Mixed woodland within an operational treatment works
Species encountered: Wood Mouse (Apodemus sylvaticus); grass nests and other evidence of nest box use

Field Notes

Today I took part in my first Hazel Dormouse (Muscardinus avellanarius) survey at the Southern Water Treatment Works in Winchester. Working as part of a team of five, we systematically checked 45 dormouse nest boxes positioned throughout the woodland habitat.

As the survey took place within an operational treatment works, full five-point PPE was required throughout the visit. With temperatures reaching approximately 28°C, the conditions added a physical challenge to the survey and highlighted the importance of balancing fieldwork requirements with site-specific health and safety procedures.

Each nest box was checked using a consistent methodology. Before opening a box, a cloth was placed securely over the entrance hole to reduce the risk of an animal escaping. The lid was then carefully opened and the contents inspected for animals, nests or other signs of occupation before the box was closed and left secure.

No Hazel Dormice were recorded during this survey. However, three Wood Mice (Apodemus sylvaticus) were found occupying nest boxes, and several boxes contained carefully constructed grass nests. These observations demonstrated that dormouse boxes can also provide useful evidence of activity by other small mammals within the woodland.

The session provided valuable practical experience of dormouse monitoring methodology, including safe approaches to checking nest boxes and recognising signs of occupation. It also reinforced the importance of following a consistent and repeatable survey protocol so that records collected over time can contribute meaningfully to long-term monitoring.

Photographs