Carnac Island is a small limestone island 8 kilometres offshore, between Garden and Rottnest Islands, south-west of Perth. The island is comprised of calcareous sandstone and lacks permanent fresh water. The coast is mostly cliffs 10-15 m high, with one large beach on the eastern shore and two smaller beaches in the west. The IBA also includes the small offshore rocks and reefs which are used by some seabirds. The average annual rainfall for nearby Rottnest island was 668 mm between 1950–95. Carnac is a popular location for fishing, as the eastern side of the island provides sheltered anchorage for boats. The island receives an estimated 12,000 visitors annually, mostly on commercial tours but also on private boats.
The island also is an important nesting habitat for several species of seabirds such as Little Penguin (50-80 pairs in 1980; most northerly breeding site in WA), Wedge-tailed Shearwater (140-200 pairs in 1980), Pied Cormorant (450-550 pairs in 1980 and 1993), Pied Oystercatcher (1-2 pairs in 1980), Caspian Tern (a handful of pairs in 1980), Bridled Tern (50-100 pairs in 1980), Crested Tern (about 200 pairs in 1980) and Silver Gull (3000 pairs in 1977/8 and 3000-4000 in 1980) (Wooller and Dunlop 1979; Dunlop and Storr 1981; Abbott et al. 2000).
Non-bird biodiversity: Australian Sea-lions use Carnac Island as a haul-out area during the non-breeding season. A large population of tiger snakes inhabits the island.
Pressure/threats to key biodiversity
Visitor access regulations, signage and fencing should be adjusted seasonally to protect the variable location of Fairy Tern breeding colonies. The breeding success of Fairy Terns should be investigated to determine the impacts of various threats.
Conservation responses/actions for key biodiversity
Fairy Tern nesting beaches are roped-off and signed by DEC.
Carnac Island Nature Reserve.
Western Australian State Government with management the responsibility of WA DEC.
Site access / Land-owner requests
Day visits are allowed with licensed tour operators.
Sue Mather provided much of the underlying data.
BirdLife International (2022) Important Bird Areas factsheet: Carnac Island (Perth). Downloaded from
http://www.birdlife.org on 04/10/2022.