Brownsea Island by third parties, is owned by the National Trust. Most of the buildings are situated near the small landing stage. The northern portion of the island is a Nature Reserve managed by Dorset Wildlife Trust and an important habitat for birds; this part of the island has limited public access. A small portion to the southeast of the island, along with Brownsea Castle, is leased to the John Lewis Partnership for use as a holiday hotel for staff, and is not open to the public. The island forms part of the Studland civil parish in the Purbeck local government district.
Brownsea Island in winter, when more than 50 per cent of British bird species (over 1500) can be present. Some imported stonework and statuary on the island serves as a habitat for a Mediterranean land snail, "Papillifera bidens". The first records of inhabitants on Brownsea Island occurred in the 9th century, when a small chapel and hermitage were built by monks from Cerne Abbey near Dorchester. The chapel was dedicated to St Andrew and the only resident of the island was a hermit, who may have administered to the spiritual welfare of sailors passing through Poole Harbour. In 1015, Canute led a