Capricornia Cays

Country/territory: Australia

IBA Criteria met: A4i, A4ii (2009)
For more information about IBA criteria please click here

Area: 241 ha

Protection status:

BirdLife Australia
Most recent IBA monitoring assessment
Year of assessment Threat score (pressure) Condition score (state) Action score (response)
2008 high not assessed not assessed
For more information about IBA monitoring please click here

Site description
This IBA consists of the many small, low lying islands (~ 241 ha in total and between 2–18 metres high) comprising the Capricornia Cays of the southern inner Great Barrier Reef south of Rockhampton and Gladstone. The three largest islands, North West, Masthead and Heron, support the largest numbers of nesting Black Noddies in the Great Barrier Reef. The IBA also includes Tryon, Wilson, Wreck, West Hoskyn, Fairfax, Lady Musgrave and Lady Elliott Islands (other islands lack seabird data or have supported much smaller numbers of seabirds). Heron Island (16 ha), which supports an increasing and high density population of nesting Black Noddies, is half residential development, half National Park (29,349 breeding pairs of Black Noddy in 1982, 36,855 pairs in 1983 and 40,718 in 1985). Masthead Island (56 ha) is dominated by Pisonia grandis trees (20,000-24,500 pairs Wedge-tailed Shearwater in 1983-1985; 65,280 pairs of Black Noddy in 1983). North West Island is the second largest sand cay on the Great Barrier Reef (90 ha) and is forested with Pisonia grandis (271,710-288,000 pairs Wedge-tailed Shearwater in 1982-1985; 60,030 breeding pairs of Black Noddy in 1982 and 93,510 in 1983). Other significant islands include Tryon Island (10 ha cay with 16,000-26,000 burrows of Wedge-tailed Shearwater), Wilson Island (4.5 ha cay with tourist accommodation managed by Heron Island Pty Ltd; up to 500 nests Roseate Terns), Wreck Island (5.5 ha; 6500 pairs Wedge-tailed Shearwaters in 1982/3), West Hoskyn (1 ha; 15,000-26,000 pairs Black Noddy), Fairfax Islands (2-3 islands covering 19 ha; 7000-12,000 pairs Black Noddy; 1000-4000 pairs Brown Booby in 1984-1994 on Fairfax no.2), Lady Musgrave (4 ha; 11,000-16,000 burrows of Wedge-tailed Shearwater; 29,000-56,000 pairs Black Noddy), Lady Elliott (35 ha island with a tourist resort which is half forested with Casuarina equisetifolia; 3500 nests Crested Tern in 1985, thousands in 1986-1989). The region is sub-tropical, receiving an average 1062 mm rain anually(to 1989), average temperatures of 16-30 degrees and one tropical cyclone every two years. The whole area is in the Great Barrier Reef Marine Park; islands are variously in Preservation Zones (Wreck Island only), Conservation Park Zone or Habitat Protection Zone.

Key biodiversity
Other birds have not been documented for this IBA.

Non-bird biodiversity: North West has the second-largest Green Turtle colony in the world.

Recommended citation
BirdLife International (2020) Important Bird Areas factsheet: Capricornia Cays. Downloaded from on 16/02/2020.