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Michaelmas Cay

A low lying vegetated sand cay encircled by a spectacular fringing reef, Michaelmas Cay is a National Park and a protected sanctuary for migratory seabirds.


About Michaelmas Cay

Michaelmas Cay is a small, vegetated sand cay:

  • Located on the western tip of Michaelmas Reef 43km north-east of Cairns and 17km north of Green Island.
  • The vegetated coral reef island covers an area of 1.8 hectares and rises to a height of 3.5m above sea level.
  • Around 360m long x 50m wide.

For a period during the late 1800s and early 1900s the island was used by sea cucumber pickers (Beche-de-mer) and for guano mining. In 1937 it was declared a fauna sanctuary and formally a national park in 1975. The Cay has cultural significance to the local Gungandji, Mandingalbay-Yidinji and Yirriganydji indigenous peoples.

How the Sand Cay formed

Michaelmas Cay was formed by the accumulation of broken coral, shells and remains of calcareous algae, continually washed over the reef by currents. Seeds deposited by visiting birds over time, and the resulting vegetation, helped to stabilise the cay. The formation of beach rock (sand and other reef remnants cemented into a rock by the action of algae) further stabilised the cay. The seeds carried in by the birds and the waves help vegetation flourish which in turn provides an ideal habitat for the seabirds to roost and nest.

A rich marine life

The Cay is rich with a myriad of sea life including green sea turtles (which occasionally nest on the cay), molluscs and invertebrates of all kinds and hundreds of species of tropical reef fish including Humphead Maori Wrasse. The reef surrounding the Cay is especially renowned for its abundance of giant clams.

Cay Flora

The Cay’s vegetation is low growing and composed of grasses including sand spinifex Spinifex sericeus, stalky grass Lepturis repens and other cover such as goat’s foot vine and bulls head vine and Sea purslane Sesuvium portulacastrum.

Access to Michaelmas Cay is only allowed between 9.30am and 3pm daily and is limited to the restricted access area marked out by rope.

A Protected Bird Sanctuary

Michaelmas Cay is a major natural seabird habitat and one of the most important in the Southern Hemisphere. It is home to at least 23 species of seabirds. Many breeds find this island an ideal nesting habitat and is one of the most significant bird sanctuaries on the Great Barrier Reef. At the height of nesting and breeding season (during Summer months) up to 20,000 birds have been observed. Breeding activity occurs throughout the year, most of the seabird species breed annually, Sooty Terns breed every 8.5 months.



Map of Michaelmas Cay: