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Location Australia, Queensland
Central coordinates 145o 58.76' East  16o 36.31' South
IBA criteria A4i
Area 2 ha
Altitude 0 - 4m
Year of IBA assessment 2009

BirdLife Australia

Summary Michaelmas Cay is a well-studied island off Cairns which has supported more than 1% of the world population of Crested Tern and Lesser Crested Tern.

Site description Michaelmas Cay is about 40 km east of Cairns in the northern Great Barrier Reef. It is a vegetated sand cay, and covered about 360 m x 50 m in 1984, but is subject to erosion and accretion. The cay is comprised of coral sand with low mats of grasses and herbs, which vary in extent between seasons. It is zoned as a Marine National Park, allowing boat limited visits and diving.

Key Biodiversity Small numbers of breeding Roseate Tern, Black-naped Tern, Sooty Tern (regular counts of 5,000-10,000 pairs), Crested Tern, Common Noddy (max 6000+ pairs in 1982).

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Lesser Crested Tern Thalasseus bengalensis resident  1982-1992  1,000-1,623 nests  A4i  Least Concern 
Greater Crested Tern Thalasseus bergii resident  1982-1992  2,000-6,080 nests  A4i  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 whole area/population (>90%) no or imperceptible deterioration low

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Great Barrier Reef World Heritage Site 34,870,000 protected area contains site 2  
Michaelmas and Upolu Cays National Park 3 protected area overlaps with site 2  


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

Land ownership Australian Federal Government with management the responsibility of GBRMPA.

Land use

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

Protection status The IBA overlaps with Michaelmas and Upolu Cays National Park.

Acknowledgements Paul O'Neill provided advice and access to the GBR seabird database and the nomination was prepared in consultation with Mike Short.

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 Great Barrier Reef Marine Park Authority unpublished report.

King, B.R. (1985) Michaelmas Cay, Great Barrier Reef, Queensland. Corella 9: 94-96. 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: Michaelmas Cay. Downloaded from on 23/10/2016

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