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Location Australia, Queensland
Central coordinates 143o 7.28' East  11o 30.24' South
IBA criteria A4i, A4ii
Area 210 ha
Altitude 0 - 46m
Year of IBA assessment 2009

BirdLife Australia

Summary These 10 seabird islands (or island groups) have supported more than 1% of the world population of Pied Imperial-Pigeon, Roseate Tern, Lesser Crested Tern, Bridled Tern and Grey-tailed Tattler.

Site description 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.

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

Non-bird biodiversity: Green and Hawksbill Turtles.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Grey-tailed Tattler Tringa brevipes non-breeding  1985-1999  1,150 individuals  A4i  Near Threatened 
Lesser Crested Tern Thalasseus bengalensis resident  1982-1992  1,000 nests  A4i  Least Concern 
Roseate Tern Sterna dougallii resident  1982-1992  6,000 nests  A4i  Least Concern 
Bridled Tern Onychoprion anaethetus resident  1982-1992  6,000 nests  A4i  Least Concern 
Torresian Imperial-pigeon Ducula spilorrhoa resident  1979-2002  24,397 breeding pairs  A4ii  Least Concern 

IBA Monitoring

2008 high not assessed not assessed
Medium - based upon reliable but incomplete / partially representative data

Climate change and severe weather storms and floods likely in long term (beyond 4 years) whole area/population (>90%) moderate to rapid deterioration high
Human intrusions and disturbance recreational activities happening now small area/few individuals (<10%) no or imperceptible deterioration low

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Denham Group National Park 91 protected area overlaps with site 62  
Great Barrier Reef World Heritage Site 34,870,000 protected area contains site 210  
Saunders Islands National Park 19 protected area contained by site 19  
Sir Charles Hardy Group National Park 129 protected area contained by site 129  


IUCN habitat Habitat detail Extent (% of site)
Coastline Sand cays, islets & bars  100%

Land ownership Commonwealth Government with management the responsibility of the GBRMPA.

Land use

Land-use Extent (% of site)
nature conservation and research 100%

Protection status The IBA overlaps with four protected areas including the Great Barrier Reef World Heritage Area.

Acknowledgements Paul O'Neill provided advice and access to the GBR seabird database.

References GBRMPA (1997) Guidelines for Managing Visitation to Seabird Breeding Islands. Unpublished report. Great Barrier Reef Marine Park Authority.

King, B.R. (1989) Magra Island, Great Barrier Reef, Queensland. Corella 13: 47-48.

King, B.R., Hicks, J. and Oldroyd, A. (1989) Cholmondeley Island, Great Barrier Reef, Queensland. Corella 13: 41-42.

King, B.R. and Limpus, C.J. (1989) Saunders Island, Great Barrier Reef, Queensland. Corella 13: 45-46.

King, B.R., Limpus, C.J, Hicks, J. and Oldroyd, A. (1989) Wallace Island, Great Barrier Reef, Queensland. Corella 13: 43-44.

Higgins, P.J. and Davies, S.J.J.F., eds (1996) Handbook of Australian, New Zealand and Antarctic Birds. Volume 6: Snipe to Pigeons. Melbourne: Oxford University Press.

Queensland Parks & Wildlife Service (2007) GBR seabird database (accessed May 2007).

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Cape York to Cape Grenville Islands. Downloaded from on 21/10/2016

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