Michelmas Cay, Great Barrier Reef

It is an all day outing to get to and return from Michaelmas Cay. The ride is over an hour-and-half both coming and going; but the four or five hours spent out there are very special. The cay has a dune-ridge (low island) of coral sand that reaches out of the water and provides a landing place for visitors and about 25,000 terns and boobies. The Cay is a sanctuary and the rights to occupancy are one hundred percent avian. Human visitors are asked to stay within a rope that encloses a rectangle about 150 feet by thirty feet That is about fifty meters by 10 meters in the rest of the world, including Australia.

Upon arriving in the area the boat crew gets ready a semi-submersible (actually partially submerged) vessel and gets the shore-ferry ready to travel back and forth from the catamaran to the beach. That usually means taking possession of the boats from lots of Brown Boobies and Brown Noddies that enjoy the floating perches. We will snorkel from the beach and take a tour in the semi-submersable (looking out the glass sides at the coral reefs and animals). While here it is impossible to avoid noticing (hearing, seeing, smelling) the birds. There are often tens of thousands of birds here. Most abundant are the Brown Noddies and Sooty Terns. These two species of pelagic terns nest on the island in large numbers. In addition there are a couple thousand Greater Crested Terns and a few Lesser Crested and White-fronted Terns as well. Brown Boobies seem more common in the past few years with numbers reaching about two hundred. There are a few Magnificent Frigatebirds and Silver Gulls and the occasional Ruddy Turnstone rounds out the avian population.

The GBR is about 1400 miles long if you start up north near the equator in Papua New Guinea and follow it down below Brisbane. There are maybe 900 islands along the reef and there are about 2900 individual reef heads. There are inshore as well as mid and outer reefs. It is a huge and diverse ecosystem. No two reef areas have the same populations of fish and coral. There are concessions granted by DOC which allow certain activities in specific areas. Cairns and Port Douglas are the two major GBR starting points. This part of Australia is occasionally battered by cyclones and there are poisonous jelly fish (Box Jellies) at specific times of the year in the inshore waters. There are turtles and sharks in addition to the reef fish. Most areas offer rich fish diversity without diving; floating along breathing through a snorkel is all you need. There are many reef-tour vendors in the area, so look into the various offerings and find one that does what you want. Some are for divers, others are from a land based island, and others are from a floating platform. There are a few companies that use a coral island. The high season can be busy and Chinese New Years is especially crowed. This is a part of the world that has a strong Asian bias as South Korea, Japan, and China are much closer than the US and Europe.

The arc in the lower left is a jet engine, the small white boomerang shaped thing in the middle is Michaelmas Cay from up high, near the jet engine. The shaded areas all around the cay are the reef heads. This area is rich in coral heads but land above the sea is not very common. That is what makes Michaelmas so special; you can get out and walk on it. The sand is coral; it was placed there by cyclone-tossed seas – The Coral Sea. The sand is created by the battering of the cyclones as well as the constant gnawing of coral by certain of the reef residents. The outer layer of a coral reef is alive and has enough sustenance to support some of the larger fish of the area.

The Brown Boobies have increased in the past few years. That is not a long enough time span to think anything special is happening but it is something I have noticed. Dave O’Brien the marine biologist who works the boat we use doesn’t think much of the numbers one way or another. But to my eye there are more of these birds and more breeding pairs. The adults are like Brown boobies that world over. This species is pretty much worldwide between the tropics (of Cancer and Capricorn – equatorial I guess might be a better way to say it).

The youngsters are white, fluffy, and goofy. The Brown Booby is a ground nester and thus needs a place, often islands, without predators. Many birds of this sort were affected by whalers, sealers, buccaneers, pirates, and early colonists who released and/or brought with them domestic animals for food and companionship. Cats, dogs, pigs, goats, sheep and several other animals were often left on their own for later harvest or simply jumped ship when near land. These animals had a significant impact (and still do) on the life of the Australian and (especially) New Zealand coasts.

It is usually assumed that birds are appropriately called by the demeaning phrase – bird brain. This Brown Booby shows that occasionally within the population there is a high-tech nerd bird.

As we tie up in the shallow waters off the cay we are allowed by the Department of Conservation (DOC) to distribute two kilograms of chopped fish. This attracts the larger fish of the reef for a bit of a snack. The large dark fish near the top is a trivially and it slashes through the feeding area like a rocket. The Red Sea Bass are quite slow in comparison.

The Brown Noddy (or Common Noddy) is a pelagic tern. It is an ocean bird. When traveling out from Cairns you don’t see noddies until you actually reach the cay and get to the ocean side of the island. They almost never fly toward land. The noddy is also pan-tropical occurring everywhere in the equatorial oceans.

Noddies are pelagic, but in nesting times they seem to enjoy loafing on the shore. It is a hectic scene with thousands of terns milling around but I have to assume that the pair splits duties at the nest and then one can preen and relax on the beach both before and after going fishing. Once the young are fledged they are all out to sea. Here a cluster of noddies is joined by a single Great Crested Tern.

Adults have a soft gray crown from the beak back over the crown of the head. There are actually three species of noddies around the world; Brown or Common, Black, and Lesser. Occasionally there is a Black Noddy in with the Michaelmas Cay Browns. But not often.

There are both Lesser and Great Crested Terns on the cay. These terns are also called Swift Tern or simply Crested Tern. But the Greats are by far the most common of this type. They are quite large and generally return from foraging at sea with a smallish flying fish in their beak. The group together on the backside of the cay but fly out over the front and out to sea. This is the only tern that is likely to be seen on the boat trip out from Cairns, and then only a few.

The Sooty Tern (or Wide-awake) is another pelagic tern. Here one straddles her egg providing a bit of shade of a one hundred degree afternoon. Here in my New England home the tern and other birds actually incubate their eggs, keeping them above one hundred degrees. In tropical Australia equal time is spent shading the eggs from the blazing sun. Incubation is a night time activity for the most part. This species don’t breed until it is about seven or eight years old. It spends those first six or seven years at sea.

Here an adult climbs aboard a coconut while the mobile, but flightless, youngster snuggles up to the husk. There are two other species of tern that might be seen here on Michaelmas Cay as well; the White-fronted and the Bridled. I have seen them both over the years and will include them in another page on the reef. I will also do a future blog page on the fishes and mollusks of this spectacularly biodiverse region of the planet.