The reserve opened in 1966 and is chiefly lowland heath, noted for the rare heather known as Dorset heath (Erica ciliaris), and for its breeding Dartford warblers. It also has acid grassland, salt marsh and woodland, with reedbeds adjoining the mudflats of the harbour.[5] Other important species include nightjar, woodlark and, on the mudflats, spoonbill.[6][7]
The reserve has a substantial herd of sika deer. Originating in East Asia, these animals escaped from deer parks during the 1860s and have now become naturalised, living on the heath and oak woodland of the site.[4]
Arne is renowned for its natural environment, and has been featured on the BBC's Countryfile and Winterwatch programmes.[8][9] Starting on Monday 29 May, BBC’s Springwatch broadcast from Arne over a 3 week period.