Shags: here there & everywhere

Symmetrical cormorants and fake owl for crop

A pair of great cormorants not at all threatened by a plastic owl

I think I’m slowly overcoming my prejudice against ducks.  My duckism, if you like.  There’s a sudden movement on the waterline, I fumble for my camera, then I realise it’s “just a duck”.

But slowly I’ve been persuaded that ducks are worth the effort.  There’s the crazy goitre of the musk duck.   The hardhead, gruesomely named after the challenges taxidermists faced stuffing its cranium.  The nest-thieving pinkeared eared duck, with its black and white stripes and hints of neon.  The good-looking but possibly feckless chestnut teal, said to engage in “dump laying” – dropping eggs in other teals’ nests to be raised. Even shooters participating in the autumnal “kill a duck in a national park” festival aren’t allowed to blow away the increasingly rare blue winged Australasian shoveler. (Field and Game Australia chair was said to be “disappointed” about this).

In the same way, I’m slowly starting to come around to the shag .  It’s not that I’ve got a particular prejudice against them.  It’s just that they’re always there.  Whatever the time of day, season or weather conditions.  Familiarity breeds not so much contempt as slight indifference.

But these foggy winter mornings have shown cormorants in a new (filtered) light.

Cormorant raft monochrome flying bird crop square

Post-apocalyptic stillness and deep chill don’t deter them.  When there’s nothing moving – maybe just a single sea-eagle enveloped in the mist – the cormorants are the silhouettes that make that gloomy snap worthwhile.

Four of the five species of Australasian cormorants can be found on my bit of the Hawkesbury.  Only the black-faced cormorant, which only lives on the south coasts – in Tassie, Victoria, South Australia and Western Australia – has never made an appearance around here.

My favourite is the biggest, the great cormorant, Phalacrocarax carbo (or the black shag in New Zealand).  It’s the world’s most widespread cormorant, found across Europe, India, Africa and South East Asia.

The little black cormorant is lovely too, with its jade green eyes and black-on-black pattern.  I’ll never forget the feathered hush of a huge flock of them passing overhead as I paddled in  in Myall Lakes National Park a few years back.  Like other cormorants, they usually nest colonially, with lots of other waterbirds.  These little black cormorants sometimes combine in flocks of hundreds to feed cooperatively as well, a line of birds trapping fish in inlets as the tide retreats.  But I’ve never seen them flying or feeding en masse on the Hawkesbury or its tributaries.

The pied cormorant is a regular sight around here too.  I haven’t seen them nesting though, even in the mangroves of Big Bay or Spectacle Island, though flooded forests – along with coastal islands – are apparently the sites they pick to raise their young.  In the past, the pied, along with the great cormorant, were suspected by fishermen of raiding nets and at times licences were distributed to cull them.  But mostly, along with crustaceans and molluscs, they eat the small fry, too insignificant to interest human fisherfolk.

I’m not so keen on the little pied cormorants – no glamorous green eye!  I see fewer of them, though apparently they do congregate in large flocks in coastal areas.  Along with the little blacks, they’re also found right across Australia’s inland waterways and dams, feeding on crustaceans, especially freshwater yabbies, as well as little fish.

Little cormorant drying wings good wave pattern crop

Little pied cormorant drying its wings at Donnybrook Bay

I say cormorants are everywhere – from the turbid shallows at the top of Berowra Creek to the open water where the Hawkesbury meets the sea.  But that’s not strictly true.  Cormorants prefer fishing over seagrass – there’s a better range of things to eat there. And seagrass beds are under threat all over the place.  A study tracking of numbers of coastal birds at a tidal bay in Victoria for over 40 years found that not only migratory birds but the year-round residents, including cormorants, had reduced in numbers:

The marked decline in some (predominantly) fish-eating birds (Australian pelican, great cormorant, little pied cormorant, white-face heron and grey-tailed tattler) around the early 1980s closely matches the beginning of a decline in commercial fish catch… Decreases in fish-eating birds and fish coincide with substantial losses of seagrass in the bay (Hansen et al 2015 524)

Cormorant about to be eaten bigger square

Cormorant avoiding a shark at Dusty Hole in Berowra Creek

And it seems, cormorants tend to steer clear of shallow water, no matter how good the spread, if there’s sharks about.  Just another reason for a kayaker to love a shag!

Egg blue sky and fog on beach at Twin Beaches

Egg the ancient kayak at Twin Beaches

Additional references:

Dorfman, E.J. and Kingsman, M.J. “Environmental determinants of distribution and foraging behaviour of cormorants (Phalacrocorax spp.) in temperate estuarine habitats” Marine Biology 2001 138 1-10

Hansen, B., Menkhorst, P., Moloney, P and Loyn, R. “Long-term declines in multiple waterbird species in a tidal embayment, south-east Australia” Austral Ecology (2015) 40, 515–527

Heithaus, M.R. “Habitat use and group size of pied cormorants (Phalacrocorax varius) in a seagrass ecosystem: possible effects of food abundance and predation risk” Marine Biology (2005) 147: 27–35

Traylerd, K.M., Brothers, D.J., Woollera, R.D., and Potter, I.C. 1989 “Opportunistic foraging by three species of cormorants in an Australian estuary” Journal of Zoology (1989) 218, 87-98

Cormorants in mist

Midwinter lagoon

It’s past the shortest day of the year, but, in spite of her scrapes and dings, Egg the elderly wooden kayak doesn’t seem to be ready for drydock yet.  Perhaps it’s that last unseasonable whirl of autumnal warmth, caught alongside the coast in the East Australian Current, that’s keeping the sea a balmy 20 degrees.  Or perhaps it’s just the lure of still, winter water all around.

Since Egg was first laid in our driveway a year ago, I’ve been seeing Sydney differently.   Those long roundabout routes from A to B via M and Q and P, punctuated somewhere along the way by a bridge or two, suddenly make sense.  The city of roads and buildings retreats and, I feel, just out of sight on every side, the presence of water.
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This is our backyard, encircled by the salty embrace of the Hawkesbury estuary.  But it doesn’t end here, with the secretive topography of flooded river valleys. All the way up (and down) the New South Wales coast, the shoreline is flanked by coastal lagoons. I’m not complaining, even the tiniest little bit, about all these sheltered waters.  But I’ve started to wonder what geographic accident has given a timid canoeist so much to feel grateful for.

Along with marshes and flats, coastal lagoons make up maybe 10% of the world’s seaboards, and in NSW lots of us live by them, many more than by the ocean itself. Lagoons (or wave-dominated estuaries – there are ongoing hissy-fits around these definitions) appear where low-lying plains, rather than dramatic cliffs, meet a shallow gently sloping seabed.  Usually, they are found on shores shaped mainly by waves rather than big tides, with underlying rock that crumbles nicely into beach sand not finer, silty sediment.

The more sand the better – perhaps our generous continental shelf harbours this bounty from a time when the Sydney Basin was a enormous braided river delta, like the Ganges today.  But you don’t want too much rain – lagoons are usually fed by an underwhelming little creek or even just groundwater – that doesn’t (or doesn’t often) burst through the land between waterway and ocean.

To make a lagoon*, you need a barrier to the open sea.  In the nineteenth and first part of the twentieth century, coastal geomorphologists duked it out over just how these barriers were born.  Did breaking waves make for ever-rising off-shore sand bars?  Did encroaching seas submerge coastal dunes? And then there’s the third, attractively named “spit accretion theory” (Davis and Fitzgerald, 2004).  Not, as it might sound, a creation myth where bunyips drool into puddles between the dunes; just sand clinging to rocky headlands as it is carried along the coast by the (delightfully piratical) longshore drift.

It turns out that everyone was right, at least some of the time.  Which is nice.  It’s hard to keep the heat in a scientific controversy when lots of the evidence, hidden beneath the surface of the sea in the first place, has been washed away or covered over during the last few millenia by terrestrial silt or aeolian sand.  Who could be angry with such mellifluous and frankly otherworldly-sounding geomorphologies in play?

Most lagoons have only been around for a little while, geologically speaking, formed after sea levels began to rise as glaciers melted 18,000 years ago or thereabouts. Many, like Narrabeen Lake, which we whizzed round on our bikes in the company of half the population of the North Beaches a few weeks ago, are even younger, not seven thousand years old. A blink of the eye for people who were here 50,000 years before.

Strangely, lagoons move.  Today’s surfers walk across the relics of yesterday’s drowned lakes.  Barrier beaches migrated landward, emerging from the ocean just as “marine transgressions” (that’s advancing oceans, not the naughtiness of waves) slowed.  Shaped in stable times, coastal lakes still don’t hang around for long.  This shouldn’t surprise me – I know that, despite appearances, beaches are really rivers of sand.
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If the tides were higher, if the rivers was faster or siltier, if Australia wasn’t so seismically serene, the lagoons would fill up and dry out or be washed away, and the cormorants would have to hunt elsewhere.  In fact, for all our dredging and draining, it’s happening right now.  Like life itself, coastal lagoons are a transitory phenomenon, a passing pleasure.
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But sometimes, under the fresh sand and brackish water there are older and odder things. The beautiful Myall Lakes, where we not long ago spent a glorious weekend, lie in the bed of an ancient river, separated from the sea not just by dunes that arrived ten minutes ago (okay, 2,000 years ago) but also by the Inner Barrier, deposited before the last glacial maximum and thirty times older.
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And then there’s the gyttja, something so very special it’s found nowhere else in Australia, and helps qualify Myall Lakes as a unique protected wetland.  What is it?  Well, rotting pondweed.  No, I’m underselling it: it’s up to 70cm of  “a highly mobile and organic mud that has a gelatinous appearance”, a “flocculent green–brown material” (Drew et al 2008), “an uncompacted, anoxic and sulphurous ‘ooze'” made from “the decomposition of charophytes, macrophytes, cyanobacteria and algae”.  Strangely, not so much about the ooze in the National Parks brochures.  But it’s an ooze that’s been there for, perhaps, a thousand years.

I’ve been thinking about lies beneath the surface of the water and the windblown sand.   But paddling through the Broadwater two weeks back, in a startling moment I found myself not gliding above the mysteries of quiet waterways, but surrounded, right amongst it.  A huge flock, a murmuration almost, of little black cormorants, perhaps returning from a fishing trip, passed above and on one side and on the other without a single cry but with a sound I’ve never heard before: the white noise of hundreds and hundreds of moving wings.

The sound of the midwinter lagoon, all around me.

* Be warned: there’s a chance my account of the origins of coastal lagoons is completely wrong.  After all, the New South Wales coast “has provoked many questions and various degrees of controversy” (Thom, 2010, 1238).  And perhaps it’s “premature to attempt a comprehensive analysis of coastal lagoon evolution and dynamics when so many lagoons have been so little studied” (Bird, 1994, 13). In case you want to check my workings:
References
  • Bird, Erik (1994) “Physically setting and geomorphology of Coastal lagoons”  in Kjerfve, B. (ed) Coastal Lagoon Processes, Elsevier
  • Davis, R. and Fitzgerald, D. (2004) Beaches and Coasts, Blackwell Science
  • Drew, Simon Iona Flett, Joanne Wilson,Henk Heijnis, C. Gregory Skilbeck (2008) “The trophic history Myall Lakes, NSW, Australia”  Hydrobiologia 608
  • Eyre, Bradley and Damien Maher “Structure and Function of warm temperate east Australian lagoons: implications for natural and anthropogenic changes” Coastal Lagoons: Critical Habitats of Environmental Change, dited by Michael J. Kennish, Hans W. Paerl
  •  Martin, Louis and Jose Maria Landim Dominguez (1994) “Geological history of coastal lagoons” Kjerfve, B. (ed) Coastal Lagoon Processes, Elsevier
  • Masselink, Gerhard and Hughes, Michael (2003) Introduction to Coastal processes and geomorphology, New York, Oxford University Press
  • Thom, Bruce, Hesp, Patrick, Bryant, Edward (1994) “Last glacial ‘coastal’ dunes in Eastern Australia and implications for landscape stability during the Last Glacial Maximum” Palaeogeography, Palaeoclimatology, Palaeoecology 111 (3-4)
  • Thom, Bruce (2010) “New South Wales” Eric Bird (ed) Encyclopaedia of the World’s Coastal Landforms, Springer