Noctule bats are the UK's largest bat species. Their summer maternity roosts in veteran trees are critical welfare and conservation resources that require protection from development and forestry.
Noctule bat welfare during the summer maternity season is directly affected by roost security. A maternity colony disturbed during early June - when dependent pups cannot thermoregulate independently - faces catastrophic pup mortality. Pups separated from mothers in the aftermath of roost disturbance die from hypothermia within hours. The legal requirement for bat surveys before tree removal exists precisely to prevent this welfare outcome. Veteran trees earmarked for removal that harbour noctule colonies require careful mitigation - alternative roost provision, seasonal fencing, and careful timing - to prevent pup deaths.