Saturday, 12 April 2014

Capricornia Cays Survey Holiday – 4. Fairfax Island’s Brown Boobies

The morning of the final day of our trip would be taken up with surveying the Brown Booby colony on East Fairfax Island, just a short sail to the north of our overnight anchorage at Lady Musgrave Island, and by 8:00 am we had made a crunching corally beaching in the tender and were marvelling at the sight of thousands of boobies both in the air and on the ground.

We were greeted to East Fairfax Island by a swirling throng of Brown Boobies (Sula leucogaster).
The Fairfax Islands comprise East Fairfax and West Fairfax Islands, each quite small and separated only by a narrow channel. West Fairfax, which we didn’t visit on this occasion, appears to be reasonably well vegetated with pisonia, but East Fairfax is quite different in nature and feel to the other islands we had visited. It has little sand and consists essentially of an undulating expanse of coral rubble of cobble-sized chunks and shingle, which does not make for easy walking. On the windward side this is piled up by wave action into low cliffs. There is only sparse and low vegetation over most of the island, generally composed of resilient, weedy, pioneering species, with just a narrow strip of trees along the lee side.

The edge of the Brown Booby colony on East Fairfax Island. The Reef Heron is in the background, and the taller vegetation in the top left corner of the photo is on north-east tip of West Fairfax Island. 

This distinctive landscape is essentially the consequence of the islands being used for target and bombing practice by Australian military forces from 1943 through to the 1960s. The islands are now off limits to the public, only partly due to unexploded ordnance that almost certainly still exists on the islands, and it was a privilege to be able to visit for the purposes of checking out the Brown Boobies.

The windward side of East Fairfax Island. The shallowly undulating nature of the island is the result of it being used for bombing practice during and after WWII. A large crater near the island's central windward edge is filled with brackish water to form a small lake. 

The booby colony covers the entire area of East Fairfax, and in the central portion of the island nest sites are densely packed, many only pecking distance from their neighbours. Nests are a simple affair being little more than a slight depression in the rubble; nest décor is minimalist, seemingly based on whatever might have been close to hand (beak!), and sadly, including a range of plastic detritus.

Under bright, tropical skies, the pure white down of the booby chicks merges with the bleached whiteness of the coral rubble. This mother has amassed a comparatively large amount of dried vegetation to pad the nest. 

The breeding period can be fairly extended, and there was everything from birds on eggs to fledged young to be counted. Because of the sheer numbers of birds involved, to achieve this we split into pairs with each team counting a different age class – Chris and I were counting young at the ‘fluffy chick’ stage, others would count juveniles, or sub-adults, or adults etc, based essentially on plumage characteristics. Counts were made in ‘blocks’ or ‘sectors’ as we slowly circumnavigated the island in an anti-clockwise direction, from which the overall size and composition of the colony would be estimated.

Counting young Brown Boobies with the aid of binoculars. (Photo courtesy of Chris Lloyd)

While surveying, we ourselves were constantly being surveyed by inquisitive adult boobies.
Brown Booby chick - almost full sized, but still entirely in fluffy white down - with dad.
Wing and tail feathers are first to emerge from the down. 
An intermediate-plumaged young bird between mum on the left (yellowish bill with small blue spot in front of eye) and dad on the right (with blue facial flush to most of the bill).
Like teens of some other species, they can look a little scruffy...
The full range of plumages from downy chicks to smartly brown and white adults.
I'm not sure at what stage the young take their first flight but it is clearly well before adult plumage is attained.
Adult female in flight. 
The degree and intensity of the blue facial flush of an adult male Brown Booby varies, presumably related to the stage of breeding. 
Walking back along the lee side of East Fairfax at the end of the booby survey. 

Apart from the Brown Boobies, the island also supports a range of shorebirds and seabirds, and we recorded Bar-tailed Godwits, Ruddy Turnstones, Pied and Sooty Oystercatchers, Black Noddies, Silver Gulls, Bridled Terns, Black-naped Terns, Roseate Terns, a Buff-banded Rail and Capricorn Silvereye. Overhead, we also saw a pair of White-bellied Sea-Eagles and an amazing 16 Great Frigatebirds.

No fewer than 16 Great Frigatebirds (Fregata minor) flew over as we completed the survey. These 'pirates of the air' are large skilled fliers and harass other seabirds into disgorging their hard won catch.
The adult male frigatebird lacks the white throat and breast of the female, instead having an expandable bright red throat sac (neither expanded nor visible in this photo). 

For anyone who may have read this far and is interested, below is a summary of our itinerary and a map of our course between the various islands.

Day 1     Tue 7 Jan 2014 - Arrive Gladstone, meet the team.
Day 2     Wed 8 Jan 2014 - Gladstone to Northwest Island; set up camp, establish protocols.
Day 3     Thu 9 Jan 2014 - Northwest Island, surveys.
Day 4     Fri 10 Jan 2014 - Northwest Island, surveys.
Day 5     Sat 11 Jan 2014 – Finish Northwest Island surveys; head down to Heron Island.
Day 6     Sun 12 Jan 2014 – Heron Island surveys; explore; relax.
Day 7     Mon 13 Jan 2014 – Back to Northwest to pick up volunteers; down to survey Masthead  Island; volunteers back to Northwest Island; rest of us back to Heron Island.
Day 8     Tue 14 Jan 2014 – Heron Island to Lady Musgrave Island; survey LMI in late morning;  explore island in afternoon.
Day 9     Wed 15 Jan 2014 – Lady Musgrave Is to East Fairfax Is; Brown Booby survey; return  to Gladstone.

It was a brilliant trip and a fantastic opportunity, one that I will think back on frequently, from the wonderful people I met, to the many close encounters with birds and turtles, for a long time to come. 

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