Cooper's Island and Castle Islands

Country/territory: Bermuda (to UK)

IBA Criteria met: A1, A4ii (2007)
For more information about IBA criteria please click here

Area: 760 ha

Site description
Cooper's Island and the adjacent Castle Islands Nature Reserve are situated at the east end of Bermuda in St. George's Parish. Cooper's IslandCooper's Island is located on the eastern side of Castle Harbour and juts out into the centre of the Castle Islands. Its general alignment is from northwest to southeast. The rock type is limestone. It was a separate island of 31.4 ha until 1943 when it was connected to St. David's Island by dredged fill during the construction of the US Air Force base, now the international airport. Prior to its connection with St David's Island, Cooper's Island was one of Bermuda's largest offshore satellite islands and the most isolated and ecologically diverse. Even today it retains most of this diversity and ecological importance because the military and NASA installations have not altered the contours significantly and the superb beaches and coastline remain. Currently, the island is part nature reserve, part National Parkland and part former NASA Tracking Station lands, which were recently handed back to the Bermuda Government in 2002 with the closure of that station. The reserve and its associated Clearwater Beach National Park are currently of great importance for both recreation and public understanding of the environment. Local people enjoy hiking through one of the last remaining wild and open spaces on the islands. There is potential to convert the NASA land and buildings to a National Park and/or Nature Reserve, resulting in the creation of significant educational and visitor facilities, with associated cultural, environmental and socio-economic benefits.Castle Islands Nature ReserveThe Castle Islands Nature Reserve is located along the southeast edge of Castle Harbour with Bermuda's main island to the west and St. David's Island to the east. There are a number of open channels between these islands that connect Castle Harbour with the open waters of the Atlantic Ocean. The largest of these channels, Castle Roads, used to be an important entrance for ships through the reef line during the 17th and 18th centuries. These islands are surrounded by extensive coral reefs and sea grass beds, which provide habitat for sea turtles and many species of reef fish and other organisms. The reserve includes Nonsuch Island, which at 6.9 ha. is the largest of the more isolated Castle Harbour Islands and supports the widest diversity of habitats. It is also the site of the Nonsuch Living Museum Project, which has been managed since 1962 as a restoration of the original plant and animal communities found on Bermuda before human settlement. The island also features a former quarantine hospital complex built in the 1860's and is now used as a warden's residence with facilities for guided tours. There are three other islands in the reserve more than 1.25 ha. in size, including Castle Island (1.89 ha.) and Charles Island (1.85 ha.). These three islands also contain historically important early colonial fortifications, some dating from as early as 1612. These were built to protect the Castle Roads Channel and Castle Harbour. Considered to be the keystone of the defence, Castle Island contains no less than three separate forts. Southampton Island is also the site of a colonial fort dating back to 1620. The presence of these forts and their importance to the defence of the early capital of St George's Town has resulted in these three islands being designated as World Heritage Sites. There are also at least 14 smaller islands, less than 1.2 hectares, which are situated in the Reserve both east and west of Cooper's Island. The Castle Islands Nature Reserve is notable for supporting a diverse range of marine and coastal habitats, including rocky coastal, sandy beach/dune, coral reefs (including boiler and patch reefs), sand flats and sea grass beds. There is some consideration to declare the waters around the Castle Harbour Islands as a marine nature reserve.

Key biodiversity
The Castle Islands Nature Reserve is Bermuda's most important area for nesting seabirds. The entire world population of the critically endangered Cahow or Bermuda Petrel breeds on four islets within the reserve. In addition, the reserve is the main breeding habitat for 40-45% of Bermuda's population of White-tailed Tropicbird (local name Longtail), representing up to 700 breeding pairs. There are also a small number of Common Terns (2-6 pairs) which nest on two of the smaller islets just west of Nonsuch Island. The endemic race of the White-eyed Vireo is found on Nonsuch and Castle Islands, which have the heavier vegetative cover which this species favours. The Yellow-crowned Night-Heron, was re-introduced to Bermuda on Nonsuch Island in the late 1970's. Approximately 25 pairs now nest on Nonsuch and up to 6 pairs on Grasbury's Island on the east side of Cooper's Island.

Non-bird biodiversity: Several rare and endemic species of plant occur, including the globally threatened Bermuda Cedar Juniperus bermudiana (CR), and the Bermuda Palmetto Palm Sabal bermudana (EN). The endemic Darrell's Fleabane Erigeron darrellianus, Bermuda Snowberry Chiococca bermudiana, and Bermudiana Sisyrinchium bermudiana are also found. The smaller islands in the reserve are managed to exclude invasive alien plant species and support almost pure native plant communities including several rare species. Most of the larger islands were planted with a mixture of ornamental and native species during the 1960's and 1970's. Some of the exotic ornamental species, in particular the Australian Casuarina or Whistling Pine Casuarina equisetifolia have become invasive and attract roosting European Starlings (themselves an invasive species) from the Bermuda mainland. The Starlings release thousands of seeds of the highly invasive Brazil Pepper Schinus terebinthifolius from the mainland in their droppings so that they have readily become established. Casuarina and Brazil Pepper are in the process of being removed from Castle, Charles and Nonsuch Islands. As already mentioned, Nonsuch Island is being managed and restored as a re-creation of Bermuda's pre-colonial plant and animal communities. Much of the island is now covered with a dense, 40 year old replanted forest of Bermuda Cedar, Palmetto Palm, Bermuda Olivewood, Southern Hackberry Celtis laevigata, Yellow-wood Zanthoxylum flavum, Bermuda Snowberry Chiococca bermudiana, White Stopper Eugenia auxillaris, Wax-myrtle Myrica cerifera, Jamaica Dogwood Dodonaea jamaicensis and Virginia Creeper Parthenocissus quinquefolia. Understory plants growing in the shade of the forest canopy include rare endemic species such as Bermuda Sedge Carex bermudiana and Wild Bermuda Pepper Pepperomia septentrionalis. Coastal areas include such salt-loving native species as Bay Grape Coccoloba uvifera, Buttonwood Conocarpus erecta, Tassel Plant Suriana maritima, Iodine Plant Mallotonia graphalodes and Sea Ox-eye Borrichia arborescens. Beach and dune areas include Seaside Morning Glory Ipomoea pes-capre, Bay-bean Canavali lineata, Beach Lobelia Scaevola plumieri, Burr-grass Cenchrus tribuloides and Scurvy Grass Cakile lanceolata. It should be noted that almost all of these plants were propagated from seeds and cuttings of native plants obtained from the main island of Bermuda, many barely surviving in tiny pockets of habitat on coastal cliffs, peat marshes and relatively undisturbed cavernous rocky karst topography. The Castle Harbour Islands are also noteworthy as being the only locations the endemic Bermuda Skink, or Rock Lizard Eumeces longirostris (CR), is commonly found. The Skink sometimes peacefully co-inhabits the nesting burrows of the Bermuda Petrel. Now rare elsewhere on Bermuda, there is some evidence that the Skink also survives on Cooper's Island, which contains suitable habitat and also holds great promise in any case for restocking or translocation projects with the species. Good numbers of the endangered Green Turtle Chelonia mydas can be seen feeding on sea grass beds around Nonsuch and Cooper’s Islands. The critically endangered Hawksbill Turtle Eretmochelys imbricata is also occasionally seen feeding around the coral reefs. The West Indian Top Shell Cittarium pica is a large inter-tidal gastropod which was extirpated because of over-exploitation by 1800. It was re-introduced to Bermuda on Nonsuch Island in 1984 and has successfully bred to the point where it has re-occupied much of its original habitat on the south coast of Bermuda. It is listed as a fully protected species with the largest populations on Cooper’s and the other Castle Harbour Islands.

Recommended citation
BirdLife International (2023) Important Bird Areas factsheet: Cooper's Island and Castle Islands. Downloaded from on 02/02/2023.