Capricornia Cays Survey Holiday – 3. Heron and Lady Musgrave Islands

Walking back along the white coral sand of Northwest Island after a day of surveying. (Photo courtesy of Jade Fennel)

On our final day on Northwest Island (Saturday 11 January) there were a small number of survey transects still to finish off and while that was being done, a few of us did some more burrow occupancy methodology testing. After 32 burrows we headed back for a slightly early lunch.

At this point, we (the ‘Parkies’, the ‘birdies’, and the film crew) would be leaving the Wild Mob group and heading to Heron Island. The Wild Mob volunteers were staying on for a couple of days of rest and recreation on Northwest before we returned to pick them again in a day or so to survey Masthead Island.

Preparing the back deck of the Reef Heron for departure.

We got underway in the Reef Heron at about 12:45 h and powered through choppy seas and stiff winds to arrive at Heron Island about an hour and a half later. I spent most of the trip lying in my cabin, eyes closed, relaxed despite being tossed about to the thud and noise of water slapping against the hull, and feeling good that I felt good and not the slightest bit nauseous. It was a valuable lesson – I’d always though the best way to avoid sea sickness was to stay on deck and keep an eye on the horizon, and avoid being cooped up inside the cabin at all costs. But, at least in this situation, it seems that an enclosed cabin is fine so long as you don’t try to read or otherwise concentrate too hard.

Visitors to Heron Island are welcomed by the wreck of the HMCS Protector, placed strategically to keep the access channel open and to afford opportunities for diving and snorkeling close to shore. 

View from under Heron Island jetty at low tide.

Black-tipped reef sharks regularly patrolled the waters around the jetty. I counted 13 at one point, but they are essentially harmless to divers. Eagle Rays were also common and made spectacular leaps out of the water.

Heron Island and Lady Musgrave Island are quite different to Northwest or Masthead Islands. Both are smaller and more circular rather than long elliptical, and both cater much more to human activity. Heron in fact is more than half taken up by infrastructure including Heron Island Resort, a private commercial operation, a large research facility owned by the University of Queensland, and an extensive Parks and Wildlife ranger station.

As we had arrived early afternoon and wouldn’t be surveying the island until the next morning, we had most of the afternoon to explore. Somehow, despite the island being so tiny, I managed to lose my four exploratory companions after being distracted by something or other, and ended up wandering the beaches alone. Well, not quite alone; there were a couple of university turtle egg researchers I bumped into, and there were birds everywhere. The southern beach is largely ‘beach-rock’ rather than sand and was favoured by Pacific Reef Herons, both white and grey forms, Ruddy Turnstones and many large, green, very attractive shore crabs. The fringing casuarinas and octopus bushes on the back dunes were full of Bridled Terns, Silver Gulls were nesting at their bases, and the sky was full of Black Noddies.

Tattlers and a Pacific Golden Plover roosting on the roof of a building was an unexpected and unusual sight. 

Despite the heat and midday sun, the Black Noddies (Anous minutus) seemed to think sunbathing on the hot sand was a good idea, in groups of just a few to parties of 30 or more.

Heron Island is well named - there would have been about 30-50 Eastern Reef Egrets (Egretta sacra) - also known as the Pacific Reef Heron - scattered around the island. There are two colour forms of this species, with white being more common in northern Australia and grey predominating in the south. On Heron Island white birds outnumbered grey birds by about 3 to 1.

The white form of the Eastern Reef Egret. 

The grey form of the Eastern Reef Egret.

Ruddy Turnstones (Arenaria interpres) were remarkably well camouflaged as they foraged amongst the coral rubble. This flock consisted of about 15 birds.

Ruddy Turnstones are named for their typical habit of flipping stones over, or in this case coral, in the hope of exposing some delicate morsel.

Pacific Golden Plovers (Pluvialis fulva) were also common on the island.

And Wandering Tattlers kept a wary eye on stray photographers. 

Before dinner, Chris and I took up the kind offer and opportunity to have a proper shower and do some urgent washing in a real washing machine at the Ranger’s HQ. Ah, that’s better!

The reef egrets are clearly used to people - this one came looking for a handout late in the afternoon. 

 

Heron Island sunset. 

Next day, after the surveying was completed in just a couple of hours, there was the rest of the day to explore and relax – after all it was Sunday! In circumnavigating the island I got a good feel for what birds were about. It was good to see the different stages of development of even a common species like the Silver Gull. Although these are common birds it is rare to see them breeding as they do this mainly on isolated offshore islands.

Silver gull (Chroicocephalus novaehollandiae) at its nest with a hatchling and two eggs at the base of a casuarina tree at the back of the dune. 

 

Both chicks and eggs are beautifully camouflaged - the egg on the right is just starting to hatch and the 'egg-tooth' on the tip of the chick's beak, used to crack the egg, can be seen. 

Juvenile Silver Gulls - these guys seemed most comfortable at the edge of the water and in the protective company of a parent. 

The patterning of a young Silver Gull is quite distinct from that of the adult. 

As I wandered along, I frequently wished that Karen had been there to share things with. She had been booked to stay at the resort on Heron Island from Friday to Monday, overlapping with the time I was there, but the recent fire that destroyed the resort’s generator meant all bookings had been cancelled.

These shore crabs were very obliging in allowing me to photograph them in nuptial embrace - I'd never seen that before. I'm pretty sure they are Swift-footed Crabs (Leptograpsus variegatus) but of a strikingly green form.

Swift-footed crab (Leptograpsus variegatus), Family Grapsidae.

A giant chiton - these ones were about 12 cm long. Chitons are a limpet-like mollusc from the class Polyplacophora. This is the first time I'd seen any with such a broad 'girdle' of mantle surrounding the dorsal plates.

Apart from being good for herons, Heron Island was also good for terns. Although I had briefly seen a single Roseate Tern on Northwest Island (a new bird for me – my 590^th bird for Australia), here there was a group of five on a spit of shingle – four in breeding plumage with bright red bills, and one in non-breeding attire with a black bill. There were also lots of Bridled Terns that were very used to the presence of people and therefore allowed a close approach before taking off, there was a flock of about a dozen beautiful and delicate Black-naped Terns, several Crested Terns, and a single Common Tern that had made a buoy its own, just out from the jetty. 

Roseate Tern (Sterna dougallii) in flight - this was my only new bird for the trip, but what a bird!

And Black-naped Terns (Sterna sumatrana) will always be one of my favourites.

After going back to survey Masthead Island on the Monday (see previous blog post), on Tuesday morning we were off early to Lady Musgrave Island. This island is a favoured destination for divers who have a well-established camp site on one end of the island, and it is also a popular island for day-trippers who come over by boat from Bundaberg or Town of 1770 on the mainland.

Lady Musgrave Island is well-frequented by divers and day-trippers.Queensland Parks and Wildlife has done a great job with signage and explanations about the island's inhabitants and ecosystems. 

Weathered fallen casuarina on Lady Musgrave Island.

The small size of the island (about 14 ha) meant the surveying was again completed before lunch. Lady Musgrave has more coral rock than the other islands, scattered in large blocks across the island, like some weird lost archaeological remains in the ‘jungle’, as well as forming sizable outcrops and rock shelves along the windward shore.

Coral rock is scattered fairly extensively about the island. This terrain is not suitable for burrowing shearwaters which are restricted to the more sandy parts of the island. 

 

Coral rock, also called beach rock on these islands, is coral rubble cemented together with sand. 

Sometimes it's a lot more like coral than rock. 

Lady Musgrave, despite its small size and idyllic appearance, also demonstrated in microcosm just how brutal life on a coral cay can be. Black Noddies, as noted in an earlier post, build a flimsy nest of pisonia leaves and it would appear that they are not the most secure of platforms for a young chick to grow up on. Large numbers of chicks may fall from these nests and as the parenting skills of the adults don’t extend to looking after them on the ground, they tend to sit about quietly awaiting their ultimate fate. It is a very hard thing to witness, and in the first days we would try to perch them on some low branch in the hope that a parent would find and look after them, but it is essentially pointless. The situation is exacerbated by the pisonia trees themselves. The seeds of the pisonia are both sticky and minutely barbed and occur in dense clusters. After a good season, the forest floor may liberally scattered with fallen seeds and Black Noddies, both chicks and adults, are frequently ensnared by them. Once this happens they are doomed to become fertiliser for the pisonia trees.

A Black Noddy chicken fallen from its nest, sadly doomed.

This chick has landed in sticky pisonia seeds and won't last much longer. 

Even adult birds succumb to entanglement in pisonia seeds. 

Eventually they will decompose and be fertiliser for the very pisonia trees that killed them. 

Even something as big as a Green Turtle may be trapped by the pisonia trees. This turtle was not able to extricate itself from amongst the tree roots and would have died a slow and lonely death. All we could do was record its details (it had an identification number). 

Despite the death, life abounds on the islands in a continual cycle of renewal.

A Bridled Tern chick (Onychoprion anaethetus) in the semi shade of a casuarina.

A juvenile Bridled Tern. 

A pair of adult Bridled Terns in pair-bond display.

Mature larva of a hawk moth (Hippotion velox - Family Sphingidae) ready to pupate. The larvae of this species can vary in colour; brown forms were also seen on the island. 

An adult Hippotion velox hawk moth. After our night anchored off Lady Musgrave Island, several of these moths got into the Reef Heron's toilet and left the walls and fittings covered in wing scales. Congo, the skipper, was not amused! 

A species of golden orb spider, (Nephila sp). The tiny male lives at the edge of the much larger female's web. This one looks like he may be seducing her in preparation to mate - always a dangerous act for spiders!

A giant Capricorn Island centipede, about 15 cm long. I'm glad I didn't encounter any of these down a shearwater burrow!

That night we would again sleep on the Reef Heron, our last night aboard. A steady stream of Brown Boobies slipped past the boat against a stormy and darkening sky, on their way back to their nests on Fairfax Island after a day’s fishing. In the morning, we too would make our way over to Fairfax Island to survey the breeding colony, and that is where our thoughts now turned.

The Reef Heron anchored off Lady Musgrave Island with Fairfax Islands in the distance. 

A Brown Booby (Sula leucogaster) heading back to its colony on Fairfax Island after a day's fishing.