| Type: | protected |
| Michaelmas and Upolu Cays National Park | |
| State: | qld |
| Iucn Category: | II |
| Coordinates: | -16.6083°N 145.9725°W |
| Nearest Town Or City: | Cairns |
| Area: | 30 km2 |
| Established: | 1975 |
| Managing Authorities: | Queensland Parks and Wildlife Service |
| Url: | https://parks.desi.qld.gov.au/parks/michaelmas-upolu-cays/about |
Michaelmas and Upolu Cays is a national park in Queensland, Australia, 1409km (876miles) northwest of Brisbane and 33km (21miles) east of Cairns. It comprises two small cays on Michaelmas Reef, which forms the north-eastern section of the Arlington reef complex, within the Great Barrier Reef.
The vegetation on Michaelmas Cay is characteristic of cays found on the outer barrier reef. Low-growing, it consists of beach spinifex, stalky grass, goatsfoot, bulls-head vine, sea purslane and tar vine. Nutrients fertilising the vegetation come from seabird droppings and carcasses. The smaller Upolu Cay is un-vegetated.[1]
Michaelmas Cay is important as a breeding site for several species of terns. It has been identified by BirdLife International as an Important Bird Area (IBA) because it supports over 1% of the world populations of greater and lesser crested terns.[2] Sooty terns and common noddies also breed there. Other terns that have nested on the cay in the past include roseate and black-naped terns.[3]
Green turtles sometimes nest on the cays. The surrounding reefs have a rich marine fauna, including giant clams.[1]