Current view: Text account
Site description (2008 baseline):
Site location and context
This IBA (~215 ha in total) consists of a string of 10 important seabird islands or island groups in the northern Great Barrier Reef, from Womer Cay opposite the tip of Cape York to the Sir Charles Hardy Islands opposite Cape Grenville. All islands which have a record of more than 1% of the world population of any seabird are listed in the IBA. There have been insufficient survey visits on most islands to determine whether they regularly support these numbers of seabirds and whether other neighbouring islands also qualify; moreover, many seabirds are naturally irregular and sometimes aseasonal in their breeding. There are numerous other islands within this IBA and to the north and south. With the exception of the Sir Charles Hardy Islands (1 & 2), the islands are small low level sandy cays with variable amounts of harder coralline substrates, grass, herbs and vines, and some larger islands have Pisonia grandis trees. The islands included in the IBA are: Womer Cay (1 ha; 1000 pairs Lesser Crested Tern in 1998), Cairncross Island (2 ha; 2000 nests Pied Imperial-Pigeon in 2002), Douglas Island (2 ha; 5250 pairs Black Noddy in 1988), Cholmondeley Islet (0.5 ha; 830 Roseate Tern chicks in 1982 and 600 adults in 1986; 590 nests Crested Tern and 162 pairs Lesser Crested Tern in 1985), Boydong Island (4 ha; 1150 Grey-tailed Tattler in 1999 and over 400 in 1985 and 1987), Wallace Islet (2.2 ha; 1000 chicks of Roseate Terns in 1976 and 5000 pairs in 1986; 300 pairs Bridled Tern in 2002), Hannibal Islands (10 ha; 24,400 pairs of Pied Imperial-Pigeon), Saunders Islet (9.4 ha; 6000 pairs Roseate Tern in 1995 but often smaller numbers), Magra Islet (2.7 ha; 2700-3100 pairs Roseate Tern in 1992-1993 and 5000 adults in 2002 but only 400 adults in 1981) and the Sir Charles Hardy Islands (182 ha; 6000 pairs of Bridled Tern in 1988). The Sir Charles Hardy Islands are two large rocky islands with a sandy fringe; they are the largest and the tallest (46 m above sea level) island group captured by the IBA and constitute 84% of the total area of the IBA. Other islands with near-threshold or old counts include Bird Islands (4000+ pairs Black Noddy in 1975). All the islands are in the Marine National Park except for Cairncross Island; all the surrounding seas are in the Marine National Park except for waters around Cairncross Island and Magra Islet, which are in the general use zone of the Great Barrier Reef Marine Park.
Other birds have not been documented for this IBA.
Non-bird biodiversity: Green and Hawksbill Turtles.
Pressure/threats to key biodiversity
Monitor numbers and breeding success of seabird colonies. Raise awareness of likely impacts of sea-level rise and sea warming.
The IBA overlaps with four protected areas including the Great Barrier Reef World Heritage Area.
Commonwealth Government with management the responsibility of the GBRMPA.
Paul O'Neill provided advice and access to the GBR seabird database.
Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Cape York to Cape Grenville Islands (Australia). Downloaded from
https://datazone.birdlife.org/site/factsheet/cape-york-to-cape-grenville-islands-iba-australia on 23/11/2024.
