Scientific name: Cettia cetti
A dark, stocky warbler, the Cetti's warbler is most likely to be heard, rather than seen - listen out for its bubbling song among willow, marsh and nettles.
Average lifespan: 2 years
Classified in the UK as Green under the Birds of Conservation Concern 4: the Red List for Birds (2015). Protected in the UK under the Wildlife and Countryside Act, 1981.