If your project involves European Protected Species, which are fully protected by law, then works may require a licence, especially if works will involve disturbing the species, damaging or destroying their habitat, or killing or injuring them. European species include bats, dormice, sand lizards, otters and great crested newts.
Licences may also be required for other non-European protected species such as water voles and badgers if disturbance to the animals or their burrows will occur.
A licence application usually takes a few weeks to prepare and involves a detailed account of surveys undertaken and the actions required moving forward. Timings of works, lighting, actions, and supervision by a licensed workers are detailed in a method statement. You also need to prepare a reasoned statement giving the reasons for the project with justification (e.g. is there an over-riding public interest reason for the project). Once the application is sent off to Natural England this can take another 6-8 weeks for them to decide. Works can only take place once a licence is received. All actions in the licence must be complied with otherwise you would be breaking the law and risk heavy penalties including fines and even imprisonment. The licence allows you to carry out an otherwise unlawful action.
Acorn Ecology has extensive experience of writing and applying for licences for a number of species.