Sunday, 9 February 2014

Capricornia Cays Survey Holiday - 1. Arrival

In January this year I was lucky enough to be involved in a seabird breeding survey, taking in several of the coral cays of the Capricorn-Bunker Groups that make up the Capricornia Cays National Park and straddle the Tropic of Capricorn at the southern end of the Great Barrier Reef. The survey was organised and run by the Queensland Parks and Wildlife Service (QPWS), with volunteer assistance from four Australasian Seabird Group (ASG) members (including myself) to provide additional seabird and surveying expertise, and a dozen energetic, interested, intelligent young volunteers recruited through Wild Mob, an outfit which facilitates participation in on-ground conservation and environmental management projects.

The beach on Lady Musgrave Island with Fairfax Islands in the distance. This is fairly typical of the conditions we had to put up with for the duration of the surveys, but someone has to do it.

The project was to survey the breeding distribution and density of Wedge-tailed Shearwaters, Black Noddies, and Brown Boobies on several of the larger and more important breeding islands for these species. The islands surveyed were Northwest Island, Masthead Island, Heron Island, and Lady Musgrave Island for the shearwaters and noddies, and Fairfax Island for the Brown Boobies.

View of Lady Musgrave Island from our anchorage outside the reef flats.

This was the 2nd of three proposed annual surveys to follow up on work done in the late 1990s and 2000 to monitor the populations and levels of breeding of these species. The Capricornia cays support some of the largest remaining stands of pisonia forest, an endangered ecosystem, and consequently harbour some of the largest breeding populations of Wedge-tailed Shearwaters and Black Noddies in the world.

Mature pisonia forest (Pisonia grandis) growing on coral rubble on Lady Musgrave Island. Pisona often dominates mature coral cay vegetation and trees can be up to 20 m tall - way taller than I was expecting prior to arrival. 

Northwest Island, the largest island in the group at almost 1.75 km long and up to 850 m at its widest, is the most important breeding island for the Wedge-tailed Shearwater on the east coast of Australia - it is estimated to support about 300,000 breeding pairs, as well as 100,000 breeding pairs of Black Noddies. The smaller islands support smaller but still significant breeding colonies of these species.

The three main plant species other than pisonia on the coral cays are casuarinas, pandanus and octopus bush, which make up the fringing vegetation on these islands. 

The Wedge-tailed Shearwater Puffinus pacificus (wedgie) is an ocean-going seabird that ranges throughout the tropical Pacific and Indian Oceans. It is a burrow nester, excavating its burrows in sandy soils on islands throughout its range. The eastern Australian population breeds on islands from Montague Island (off Narooma, NSW) in the south to the islands of the Great Barrier Reef, and probably ranges in the non-breeding season to as far north as the Philippines.

Wedge-tailed Shearwater Puffinus pacificus in its more typical habitat - the open ocean. This photo was taken about 30 km east of Wollongong, NSW, in December 2013. 

On land, the Wedge-tailed Shearwater is not quite so graceful; after feeding at sea during the day they tend to sit about on the ground at night, gently wailing to each other.  

Wedge-tailed Shearwater burrows are about 2 m long and are excavated in sandy soil. Roots and fallen branches can help brace the entrance, as well as make it more difficult for surveyors to get their arms down them. 

The Black Noddy Anous minutus is a distinctive bird related to the terns; it is sooty black with a silver-white cap so is also known as the white-capped Noddy. The species has a tropical and subtropical distribution across the Pacific and Atlantic Oceans, including the Caribbean. It is essentially sedentary, is gregarious and strongly colonial in its nesting, building substantial but flimsy nests of leaves glued together with faeces. In the Capricornia cays they have a strong preference for nesting in pisonia trees, but I also saw the occasional nest in the fringing casuarinas, pandanus or even octopus bush. The Bunker Group of the Capricornia cays is the southern limit of their breeding islands along the eastern Australian coast but they also breed (further south) on Lord Howe Island.

Black Noddy in flight - mostly silhouetted but producing a distinctive noddy appearance.

Noddies are highly gregarious and may spend a lot of time sitting together in trees - here they are in an octopus bush (Heliotropium foertherianum, previously Tournefortia argentea).  

Black Noddies are stunning birds with their sooty black plumage and prominent silver-white caps and eye-liner. They nest colonially, building a nest of pisonia leaves glued together with faeces. 

The Brown Booby Sula leucogaster is also a widespread tropical species, occurring in Pacific, Indian and Atlantic Oceans, and in the Caribbean. The Bunker Group of the Capricornia cays is the southern limit of its breeding range in eastern Australia. It nests colonially, essentially in the open on exposed islands, and the nest can be as little as a scrape in the ground depending on what padding or adornments might be available. On Fairfax Island they nest on and amongst the coral rubble, each nest just snapping distance from its neighbours.

Brown Boobies in flight are both majestic and comical.

Booby chicks are pure downy white when young and progressively moult into the smart brown and white adult plumage.

I won’t pre-empt the results of the surveys; that’s the domain of QPWS, and besides I wouldn’t know; but observationally and anecdotally, it appears that the numbers of breeding birds this season may be down on last year.

Anyway, getting back to the trip itself… The ASG contingent (Chris, Mark, Dave and myself) all met up in Gladstone on the 7th, and then met up with the QPWS participants (Graham, Damon and Julie) at the Parks depot at Gladstone Harbour where the Reef Heron is moored. The Reef Heron is a great boat, customised for QPWS requirements and sleeps up to nine people. Skippered by ‘Congo’ (Andrew) with assistance from Rod, the Reef Heron would be our home away from home for a fair chunk of the trip.

Before spending our first night aboard, Dave, Mark and I got to know each other over a few beers in town, before meeting up with Chris (who I’d met a year previously on a shearwater / storm-petrel / penguin survey of the Tollgate Islands off Batemans Bay) and his partner Nadia at a local Thai restaurant.

We departed Gladstone Harbour under grey skies and encountered frequent heavy squalls on our way out to the islands. The huge catamaran ferry in the left background transports workers to the LNG developments on Curtis Island.  

Next morning dawned grey and very wet, and amongst the clatter and clutter of a heap of gear being loaded on board, we met the hitherto unanticipated (at least by most of us) film crew who would be with us for the first half of the trip. Nick, with Luke, Casper, Dan and John would be filming for a documentary on Life on the Reef to air later this year. Just after 7 am we got underway, powering through the squalls and trying to hear each other talk through our strategy and methodological approach against the constant thrum of the motor and the spatter of rain and spray against the plastic all weather ‘awnings’ that (mostly!) protected the back deck of the boat.

The trip out to Northwest Island, about 80 km north-east of Gladstone, took about 4 hours, most of which, after we gave up trying to talk, was spent testing our resilience against being thrown about a tossing boat and wondering whether we should in fact have taken those Travacalms. But, despite a vague sense of unease for a while, neither I nor anyone else succumbed, either then or at any other time on the trip. And by the time we reached Northwest Island the sun was out, the island literally sparkled against a glittering sea, and we’d seen our first wedgies and noddies on passage, and a Brown Booby and a couple of Great Frigatebirds overhead. A great start.

After waiting a while for the tide to be high enough, and for the Wild Mob group to show up on their catamaran, the Wild Cat (which had taken seven hours since before dawn to come across from Yeppoon), we unloaded a mountain of gear into the Reef Heron’s runabout tender, several times, to be ferried the final 500 m or so across the reef flats to the beach.

Our camp was tucked into the pisonia forest just beyond the beach on Northwest Island. The catamaran on the beach is Wild Mob's Wild Cat, a very nice boat!

After having lunch and meeting the Wild Mob group – Bill, Derek and Amanda from Wild Mob, and the 12 volunteers Brooke, Hannah, Robert, Dylan, Jaime, Sarah, Elizabeth, Karen, William, Morgan, Paulina and Jade - much of the afternoon was spent setting up camp and having a quick run-down of how things would operate over the next few days.

Our campsite amongst the pisonia trees (and shearwater burrows). 

Basically, we would split up into five teams of three or four people. The four teams of four would each take on several of the survey transects that would together cover the whole island. Transects cut across the island north-to-south and were labelled A to Y (the island wasn’t quite long enough to make it to Z based on the predetermined distance between transects), and each transect had from 1 to 13 survey points along it, for a total of 223 survey points. Each survey point would be of 10-m radius and all shearwater burrows and all noddy nests within that 10-m radius would be counted. Then, a sample of 10 shearwater burrows would be tested for any occupants to determine occupancy rates and ultimately give an estimate the size of the breeding population. On the other hand, the team of three (being Graham, the QPWS leader, Jade and myself) would check on several sound recording stations that had been set up by QPWS several months earlier, and assess various methods for determining the occupancy or not of shearwater burrows. (We would also cater to some of the needs of the film crew regarding the footage - what’s the digital equivalent for that? - they might want on this particular and peculiar aspect of “Life on the Reef”.)

The traditional way to determine if a burrow is occupied (i.e. it contains a nesting shearwater or egg) is to prostrate yourself on the ground amongst the grit and guano, stick your arm as far down the burrow as you possibly can (i.e until your cheek is hard up against the burrow mouth and your ear is starting to fill with sand), and if you can’t reach the end (which is most often), use a ‘waddy’ to probe to the end of the burrow and to ‘feel’ or listen (some birds object to being so probed) for the presence of a bird. A ‘waddy’ is often a 1-m length of garden hose, but may be a flexible stick, or indeed a combination of the two. It needs to be flexible enough to negotiate any twists or turns in the burrow, and sensitive enough to be able to feel if a bird is either pecking at it (similar to a ‘nibble’, or sometimes a distinct ‘bite’ in fishing terms) or shuffling away from it.

At arm's length down a wedgie burrow, feeling for occupants with a waddy. Clearly it's very hot work, but it must have still been early in the day as I'm still remarkably clean! (Photo courtesy of Graham Hemson)

Trying to improve on this time-honoured but undoubtedly crude and labour intensive methodology was one of the aims of what my team would be undertaking (though we did do transects S & T on the second day). The sound recorders were in place to detect the calls wedgies and noddies (both are very vocal!) and these would be analysed against the soon-to-be-known densities of the two species based on our 10-m counts. And we also had with us a very expensive piece of equipment called, for our purposes at least, a ‘burrow scope’. This is essentially a tiny camera (infra-red, maybe?) on the end of a long flexible wire hose which sends its signals to a wireless monitor so the images can be viewed in relative comfort. While this worked quite well, and some of the in-burrow images were very cute, its expense and relative difficulty of use is not likely to pose any threat to us traditionalists in the short term!

Graham from QPWS using a burrow scope to ascertain the occupancy of a shearwater burrow - slightly more dignified. 

By comparison, counting noddy nests is a cinch. Stand in the shade under the trees and use a clicker to count all the nests, which are pretty obvious, in a 10-m radius of the specified central point. OK sometimes you had to walk a bit to make sure you could see and count all the nests.

After being thus apprised of the technologies and prepared for what was to come, we had the rest of the afternoon off. I of course spent it roaming the nearby beach with binoculars and camera. And needless to say, I didn’t get very far. At the edge of the water just along from camp there were Pacific Golden Plovers, Pied Oystercatchers, Common Greenshanks, Bar-tailed Godwits, Whimbrel, both Wandering and Grey-tailed Tattlers, Ruddy Turnstones etc, and my bird list grew quickly.

Common Greenshanks Tringa nebularia (and Bar-tailed Godwits Limosa lapponica) on the beach at Northwest Island.

But it was the turtles that captivated me. It was nesting season and Green Sea Turtles Chelonia mydas, better known here as just Green Turtles, were in full swing. Wavering dark shapes cruising the impossibly blue-green waters just offshore would morph into apparently stranded blobs further down the beach, taking stock through bleary eyes of what was ahead before laboriously heaving their way up the beach. The back dunes amongst the casuarinas were littered with the craters of previous nights’ efforts, and every now and again plumes of sand would be thrown into the air as yet another turtle excavated its own nest chamber.

A Green Turtle clearly daunted by the prospect ahead of it as it prepares to ascend the beach.

As they make their way up the beach, the turtles frequently rest for a short while before again dragging themselves up the beach with their front flippers. 

For one turtle the ordeal is almost over, but there seems to be very little acknowledgement as they pass each other on the crest of the dunes. 

The turtles spend hours evacuating a pit before considering it deep enough to lay their eggs.

Some turtles appeared to be more energetic with their excavations than others. This one repeatedly ejected huge plumes of sand, usually one flipper at a time, but occasionally exhibited a massive double-flippered effort. 

Just metres from the water, this turtle is almost home. Its sand encrusted eyes will soon be washed clean and it will return to its much more graceful watery existence. 

Even on that first afternoon I was fortunate to witness the frantic scrabble of half a dozen new hatchlings tumbling down the beach towards the sea, desperate to do what they could to avoid the depredations of the ever-vigilant Silver Gulls that would snaffle them up in an instant. It’s surprising how soft and rubbery young hatchlings are. It’s less surprising just how cute they are!

So cute! but a still photograph cannot do justice to just how cute as they scrabble their way in frantic desperation down to the coralline sand to the water. 

Sometime around 9:30 pm (don’t forget, Queensland doesn’t have daylight saving) we trundled off to our tents. I dossed down on my thermarest – no need for sleeping bag or even sheet here - and drifted off to the 'music' (read cacophony – though some people are said to like it) of a thousand noddies and as many shearwaters cackling and wailing uninterruptedly throughout the night. Tomorrow would be a brand new day in Paradise.

1 comment:

  1. What a fantastic read, your photos and explanations made me feel I was there, just amazing.

    Even though the bird surveying was why you were there (I am not sure if I could put my arm down one of those burrows!), the sea turtles must have been magnificent to watch.

    I can’t wait to read about your next trip!