Wildlife reboot: birds 2.0

Another January, and another trip to Ganguddy, on the western site of Wollemi National Park.  Same marvellous geology, same refreshing dam water, same hot weather.

But some things were different this year.  After the stupendously dry winter, the eucalypt forest was parched, the undergrowth sparse and the leptospermum flowers of last year’s visit few and far between.  We found a patch of sphagnum moss perched in a bowl of sandstone boulders so dry it crunched underfoot.

A “green” satin bowerbird panting in the heat

We spotted plenty of lizards, and the diggers were out in force – lyrebirds wandering through the camp as they tried to scratching their way down to moisture and a wombat turning up to twerk on a picnic bench.  But up in “kingfisher alley”, just before the Cudgegong River disappears into the reed beds, there were fewer blue and green flashes by the water.

Around the camp site, the bowerbirds and treecreepers panted in the heat.  Apart from the ubiquitous reed warblers, there seemed fewer birds altogether.  No sign of the friarbird teenagers of last year, and even the baby swamp hens seemed thin on the ground.

You have to wonder what it takes to change ecosystems irrevocably.  How many dry winters before the old inhabitants decide living and breeding here is just too tricky?  And who would move in to fill their place?

Back at Berowra after the trip, there are changes in the garden too… surprising ones.

We knew we’d be losing the sparrowhawks soon enough, but the family has dispersed in an unexpected orderThe adults disappeared off the scene weeks ago, and by the time we made it home with our ridiculously overloaded vehicle and small and ancient fleet of boats, the siblings had parted too.  There’s just one young’un now.  He seems lonely.

There’s a constant plaintive calling from the trees out back, that seems to intensify when he has prey on hand.  I’m not quite sure if he’s warning his imaginary sibling off or calling him to come and share a meal.

And that’s not the only shift in the soundscape around here.  The sparrowhawks have cut a swathe through the bird population on the premises.  Baby brushturkey numbers have fallen from previous plague proportions, noisy miners are few and far between and the “house” birds of yesteryear – red and little wattlebirds – are now just occasional visitors.

But as the numbers of resident raptors has dropped, a new set of critters have settled in.  Lewin’s honeyeaters which we’ve only seen once or twice in the backyard over the last seven years, have made our backyard their new home.  And we also appear to have acquired some brown thornbills, a raptor snack food if ever there was one.  And the local eastern spinebills, another tasty morsel for a sparrowhawk, are spending more time around here too.

The only explanation I have for the change of personnel is that the hawks have bumped the notoriously territorial wattlebirds, leaving the field open for new arrivals.

I’m pretty happy to have a new set of birds in the garden.  My dream scenario, I have to admit, would be to order up some songbirds that are a bit easier on the eye.  My birdwatching brother puts Lewin’s in a honeyeater “bin taxon” of pretty similar and drab looking birds it’s hardly worth distinguishing between.  Cruel, perhaps, but fairly accurate.

So, why not some new holland honeyeaters, for instance – gorgeous looking locals.  Or (still, my beating heart!) what about some pardelotes?  Just one or two?

On the other hand, it’s possible that all the vibrantly coloured small birds in the neighbourhood have been made into multicoloured meals over the past three months by our family of raptors.  After all, there’s got to be some evolutionary reason for all those SBBs*.

*note: this is a throwaway remark absolutely unsupported by any science.

 

Previous posts about Ganguddy

A bit about Ganguddy’s history and geology – and a little Tim Low on the side

Snakes versus whining teenagers – last year at Ganguddy

 

More on our sparrowhawk summer

Death and sibling rivalry

The new generation of sparrowhawks emerges from the nest…

Baby brush turkeys versus nestling sparrowhawks… the battle of the backyard baby birds

The collared sparrowhawks return to our backyard… or are they brown goshawks?

A first glimpse of the sparrowhawks… and a beautiful white goshawk visits the washing line

 

Further reading

Stephen Garnett, Donald Franklin, Glenn Ehmke, Jeremy VanDerWal, Lauren Hodgson, Chris Pavey, April Reside, Justin Welbergen, Stuart Butchart, Genevieve Perkins and Stephen Williams (2013) Climate change adaptation strategies for Australian birds: Final Report, National Climate Change Adaptation Research Facility

Office of Environment and Heritage, Premier’s Department (2011) New South Wales Climate Impact Profile Technical Report: Potential impacts of climate change on biodiversity

Black princes, redeyes and floury bakers

My brother the twitcher has taught me the secret of finding birds.  Tune into sound: let your mind move out from the place where you are standing, into the space above you and all around you and listen.

All this summer, I’ve been listening out for the sparrowhawks.  Even lying in bed or sitting on the sofa, we could hear them begging for food or squabbling with the local cockatoos.

But come mid December, white noise and static started interfering with Radio Sparrowhawk.  The cicadas had arrived.

This year’s a biggie for cicadas in Australia.  Over 350 species of cicada have been described here, though there could be many more – we’re a diversity hotspot for these charismatic insects.  And this summer, some of the biggest and noisiest species – the cherrynoses, the double drummers and the razorgrinders – have appeared en masse around Sydney.  After maybe five or six years of living metres underground sucking on the tree-sap, the cicada instars crawl out of the earth and shed their exoskeletons for a short and noisy month or so as adults.   It doesn’t happen every year.  2013 was a big year for cicadas in Sydney, and before that 2010.  And now it’s on again.

Black prince 1 closeup nice background

Black Prince on a casuarina tree by the edge of Berowra Creek

No-one knows quite what triggers the horde of insects.  In fact, no-one knows much about cicadas at all, despite their presence on every continent except Antarctica and their impossible to ignore, earsplitting calls.  That long and decidedly boring youth, and the uncertainty about when they’ll re-emerge, makes researching them tricky.  Imagine deciding to study the periodic cicadas of North America and then realising your three years as a PhD student would be over long before the seventeen years the critters spend underground was up?

An ex cicada thanks to the local orb spiders

One theory is that by appearing so infrequently and irregularly cicadas could avoid the predators – bird, bats, all sorts of mammals – keen to feast on the insect bounty.  Very weird recent work from the US suggests that numbers of predating bird species start to drop around twelve years after the last cicada boom.  Could it be that these devious insects are manipulating the beasts far higher up the food chain?

In some ways, despite its wealth of cicadas, Berowra is less interesting for researchers than bits of Sydney not surrounded by national parks.  Australia cities are unusual, it seems, in that they still have cicada species in the heart of suburbia.  Silver princesses and green grocers survive in quite urban areas on the east coast. A local researcher (plants by day, cicadas by night) Dr Nathan Emery has been trying to work out how these species have survived, and whether there are others that can cope with city life. He’s set up the Great Cicada Blitz, a citizen science project crowd-sourcing information about when and where various species of cicadas can be found.

I’ve had a great time over the last month wandering around recording the din in our neighbourhood and trying without a lot of success to spot the earbleedingly loud cicadas to add to the Blitz database.  The male cicadas’ strategy to collectively produce a chorus so loud it hurts the ears of birds works on humans too, even those with the advantage of being partially deaf already. Apparently even the males cicadas “switch off” the equivalent of their ears (their tympana) to save their own hearing.

Thanks to helpful tips from the experts as they confirm my dodgy IDs, I’m slowly learning how to identify the common species around these parts.  Nathan Emery’s nifty little book A Photo Guide to the Common Cicadas of the Sydney Region has been really handy too. It has a lovely introduction from (and is dedicated to) Dr Emery’s scientist dad who took him and his siblings out cicada spotting as kids – inspiration to continue tormenting my offspring with my nerdy passions.  And who wouldn’t be nerdy about cicadas – an animal whose wings has in-built nanostructures that literally rip bacteria apart…

Graphical abstract

Graphical abstract for Aaron Elbourne, Russell Crawford and Elena Ivanova’s 2017 article “Nano-structured antimicrobial surfaces: From nature to synthetic
analogues” Journal of Colloid and Interface Science 508 603-616.
Shouldn’t EVERYTHING have a graphical abstract?

I should also thank the popularity of the big liquidambar in our front yard with the local insects for the chance to improve my cicada identification skills.  Adult cicadas like to latch onto thin-barked natives, but if push comes to shove they will feed on introduced trees, and liquidambars seem to be a favourite, of our local population of redeyes at least, although I think I’ve also heard calls from local tibouchina and robinia trees, as well as the local Sydney red and blue gums.

Though some cicadas don’t seem to be too fussy about the trees they sup from, you have to worry for the next generation.  In the last year, 15,000 trees – 3% of the tree cover on private land in Hornsby Shire – disappeared, thanks to a rash of tower buildings replacing the old fibros with rambling jungly backyards that used to hug the railway line.  Next gen cicadas popping out about 2023 may find nothing taller than a cordyline to sing from and property developers taking over their traditional role local bloodsucker.

Rough barked tree with cicada shell bettersquare

An exoskeleton clinging to the bark of a tall tree in a local school

I’ve not seen any green grocers or yellow mondays or silver princesses around here.  There are double-drummers in the national parks down the road – they don’t do so well in back gardens, needing an expanse of acreage or bushland to survive.  And so far we’ve heard at least four species around our yard: razorgrinders, black princes, floury bakers and the locally ubiquitous redeyes.

One of a whole bunch of redeyes high up in a Sydney red gum raining down excess tree sap on me

How do I know the red eyes are one of the most common cicadas around these parts, even before I started collecting photos and audio?  Well, that’s the gossip from the local kids.

Cicadas weren’t a feature of my childhood, growing up by the River Murray in South Australia.  But they’re a big part of children’s lives around here.  Even the common names of the local species are courtesy of kids, which explains why they are named after colours or days of the week and not dead white European men as per normal service!

My younger daughter (Anonymous Bob as she wants to be known) gave me the low down on what Berowra kids know about cicadas:

“At school in the cicada season, when the teachers aren’t looking, people climb the trees to try to catch cicadas. They climb the big thick trees because that’s where you find them. The main cicada zone is the little mossy grove next to the library. We treat them like exotic pets and look after them, until they want to be free or they die.

Once, there was a little boy. An older boy gave him a cicada to look after – it was sort of like an adoption. But the little boy decided to let him go so he could be free.

Another time, a bunch of kindies robbed a guy of his cicada. It was freshly caught and it had one leg missing, so he was desperate to protect it. They wanted to call it Princess and he wanted to call it Jeffie. They threw a ball at it while it was clinging to his shirt. It nearly fell off and died. And then the kindies started chasing the guy saying “Princess! Princess!” and then they had an attempted robbery but then a teacher came.”

Jeffrey Princess

“It’s fun to look after the cicadas. They’re kinda cute. Most cicada collectors try to find other species because in our school the redeyes are the most common. We find what they eat and take care of them. The cicadas cling onto your clothes which makes them pretty portable pets.”

Red eye cicada

Red eye at our place

“A while ago we did a thing where we would prank the teacher with cicada shells.   At first it was just a joke and then it became a whole fiesta. It became a game and a compulsory activity. Not that the teacher said it was a compulsory activity, we just made it one.

Originally it was just seven cicada shells a day but it ended up with many many many shells from each person. We gathered cicada shells, and every day we would leave cicada shells around the classroom and she would have to find them.”

Many cicada shells

A very popular grapefruit tree in my neighbour’s garden

“We found the cicada shells everywhere – on plants, on trees, on everything. A few boys were the main gatherers. They did it at school, home, everywhere. They came in with huge plastic bags full: they were the main source of our cicada shells. Sometimes we used white out and sharpies to paint war paint onto the cicada shell to make them unique.

Cicada on key ring

Graphical abstract of cicada exoskeleton on teacher’s key ri

You know how cicada shells have a slit? We slipped that onto the teacher’s key ring and when she found it, she was like “Not again!”. We started making a joke that she was cursed by the demon of cicadas.

At the very end of the year a few of the boys laid the cicada shells in a big love heart on the carpet and put a huge pile of chocolates in the middle and wrote their names on a card with love to the teacher.”

 

Cicada love heart

The love for a teacher expressed in the language of cicadas

Maybe there’s another project to be done on cicadas – a children’s natural history of these rowdy, charismatic insects…

Do you have any stories of childhood exploits with cicadas, in Australia or further afield?  I’d love to hear them!

Death & sibling rivalry

Both birds eyes crop better again

The sibling sparrowhawks in their favourite tree… in my backyard!

It’s happened. Our babies, only three weeks or so out of the nest, are now out there in the big wide world, killing for themselves.  It brings a tear to your eye.

Distant with second bird flying crop

Keeping an eye on little brother or sister

But it’s not all cheery dismemberment:  there’s trouble in the nest.  The siblings to have an uneasy relationship.  I often see them perched on adjacent branches, and when they’re further apart they call out to each other every now and then.  And when one takes off to hunt, the other often falls into line, disappearing suddenly in a simultaneous dive.

But there’s also a certain amount of what might be described in human siblings as petty jealousy.

Yesterday I stood on a chair on the deck for an hour watching one of the sibs engage in  a comprehensive preening session / extended tai chi practice.  I wonder whether this serious self-care might have been the consequence of getting tangled up in one of the humungous org spiders webs stretched out between the trees to catch dragonflies, cicadas and, for the really ambitious arachnid, a passing sparrowhawk.

Preening headless profile tail out crop b&w

… and the headless sparrowhawk

I found the “revenge of the headless raptor” impressive, but his nestmate, looking on from a high branch, seemed rather unimpressed.

Distant top brother looking down b&w

Jeering at silly sibling

But both martial arts and sneering were set aside when the fledgling in the upper branches spotted something tasty beyond the neighbour’s yard.

Juvenile sparrowhawk wings raised square

I’m off…

There was a simultaneous stoop, and then a fracas in the jungle at the bottom of the garden.

White cheeked honeyeater crop

Dinner… a white cheeked honeyeater I prepared earlier

I don’t think the squawking was the work of dinner – an unfortunate white-cheeked honeyeater (rarely seen in our yard.  I wonder why…).  I reckon the ring-ding battle was between the sibs.

The winner landed, very conveniently for me, right next to my washing line, showing the total indifference to human proximity that seems to characterize most young raptors.

 

Sparrowhawk profile left with untouched prey

The lucky sibling with significantly less lucky white cheeked honeyeater

This diffidence did not extend to the presence of little brother or sister though.

Juvenile looking behind for rival

Keeping an eye out

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Juvenile with head turned mouth open amended

 

Just a few moments after the winner landed with their prize, there was another skirmish.  Luck favours the prepared, and this youngster was in position, with wings spread out protectively around the prey like a sort of meat umbrella. Ew, what a nasty image.

The hungry one had another go, and to be honest, I’m not really sure who was successful, since neither juvenile has any distinctive marks (like a scar over one eye or a dragon tattoo or anything) I am completely unable to tell them apart.

Juvenile plucking the prey

Settling in for a good plucking

Anyway, someone had a lovely meal of raw songbird and someone sat nearby looking on and feeling sorry for themselves.

Sibling watching

Luckless sibling looking on at the feast

Nevermind, buddy.  I’m sure there’s be some tiny, tasty, rather slow birds on the menu for you sometime soon.

The backstory of the serial killers in our backyard…

The new generation of sparrowhawks emerges from the nest…

Baby brush turkeys versus nestling sparrowhawks… the battle of the backyard baby birds

The collared sparrowhawks return to our backyard… or are they brown goshawks?

A first glimpse of the sparrowhawks… and a beautiful white goshawk visits the washing line

Battle of the baby birds

There’s a festival of death going on in our neighbourhood at the moment.

Several times a day, amongst the robotic clicks of the bower birds and the squawks of the wattlebirds, there’s an insistent high pitched chittering call, often accompanied by the din of freaked out noisy miners.  I’m not 100% sure of its ethological or evolutionary significance, but as far as I’m concerned it’s a signal for me to drop everything and dart up our drive with my camera.  One of the resident pair of collared sparrowhawks – probably the male – has caught some small clueless bird and is perched in our neighbour’s radiata pine steadily eviscerating it.

He rips off the feathers and flings away less tasty bits (check out the beak mid-air above) all the while, often with his mouth full, calling out “Dinner’s up!” to his mate.

For the last few weeks she’s been spending much of her time in a the nest at the very top of another decrepit pine tree in the yard of next house along the way.  Sometimes he flies up to the nest with tasty chunks of flayed bird flesh in his claws, but I’ve also seen her fly in to the designated “disembowling” perch to join him a few times.  Occasionally, she seems to sneak away to do a little light hunting herself.  Risky, though, leaving the nest unattended.

There’s the pied currawong I saw hopping surreptitiously through the branches, warily inching towards the nest, until it was chased off by the indignant parents as it was virtually peeping over the side.  And the pair of cacophonous channel billed cuckoos I caught flapping around the neighbour’s garden a few weeks ago – apparently they sometimes parasitise collared sparrowhawk nests.

But I will be deeply unimpressed if the chicks that come out of that nest are bloody channel billed cuckoos, for all my secret admiration of those giant hornbill beaks and strapping crucifix silhouettes.

Because the sparrowhawks seem to have rid our garden of the plague of baby brush turkeys.

A whipbird seems to have taken up residence this spring.  Needless to say, I don’t have a photograph despite being nearly eye to eye with the noisy bugger once or twice.  So, tiptoeing round my backyard trying to catch a clear shot, I heard a scrabbling in the leaf litter.  “Ah, a baby brushturkey” I thought sagely.

And then it struck me… I haven’t seen a single baby turkey in our backyard this year.  Not one!  Last year, they were sleeping on top of the predator proof cage or standing outside in the daytime, gazing longingly at our flock of little baby chooks.  The year before one wandered into our pocketsized laundry and spent eight hours pacing the two foot long windowsill, failing to notice and thus escape through through the wide open door.  But this year… nada.

Collared sparrowhawks (unlike their lookalikes brown goshawks – so similar that it’s altogether possible they could be our resident raptors) catch most of their prey in flight, bursting out of their lurking places in the foliage to grab little birds on the wing.  But the baby brush turkeys that previously haunted our place do fly, right from the day they dig themselves out of their hatching place in their father’s mound of decomposing leaf litter, and start their life of unnaturally early independence.

So maybe the sparrowhawks have been catching them on those very first short flights from mound to chicken yard.

I don’t hate brush turkeys, but I do hate a having dozen brush turkeys hanging out in my backyard, sexually assaulting my chickens, nicking their food and, given half the chance, eating their eggs.  So the idea of generations of sparrowhawks breeding happily in the neighbour’s trees and keeping the local population to manageable levels is extremely appealing.

I’m starting to wonder if there’s a connection between the familiar sound of chainsaws and the plague populations of brush turkeys in Brisbane and the northern suburbs of Sydney over the last few years.  No dingoes, fewer foxes foxes thanks to baiting, and nowhere much for the local raptors to nest in suburbia these days, the tallest trees victims of fears about bushfires and death-dealing or at least car-damaging falling branches.

But today my endless blurry photos of the neighbourhood raptor nest brought good news: what seems to be a creamy ball of fluff snuggling up to its mum in the distant collection of sticks that is the sparrowhawk’s nest.  Bring on the next generation of brush turkey assassins!

How to exploit your termite work force

One of permaculture’s big ideas is makig plants and animals your agricultural labourers.  It’s not so much hitching the family Great Dane to the plough as letting your furred and feathered workers, more or less of their own free will, roam through your food forest grazing on weeds and wolfing down snails.  Say goodbye to tedious annual seed-raising, planting and hoeing: your self-reliant plants will look after themselves and keep an eye on each other, shading and nitrogenating and breaking wind (if you know what I mean).

Sometimes it works.  Our tamarillo, banana, monstera and tumeric plants have formed a chlorophyllerous collective. We have tip-pruning possums, chickens that mow the lawn and do the weeding, rat-catching diamond pythons and bandicoots on a search and destroy mission for curl grubs.  This week I even had a local katydid offering to supervise the manufacture of my home-grown pesto.

Unfortunately some of the local flora and fauna seem to have skipped crucial pages of Bill Mollison’s permaculture classics.  My custard apple tree, for instance, appears to need assistance to shed its leaves in a timely manner. Really, has it come to this? I spend my precious hours of leisure depilating fruit trees?

Meanwhile in the kiwifruit arbor, lacking both enthusiastic pollinators and RoboBees (yep, New Zealand has them), we’re having to take a prurient interest in the sex lives of our male and female kiwifruit vines. To be honest, my child labourers were about as useful as the diffident insects.  I’m baffled.  How could standing on the top of a ladder tickling plant reproductive organs with paintbrush fail to entertain?

The sorry state of my home-made kiwifruit planters remind me of another insect labour fail. Termites.  What can a permie do with them?

Thanks to our hippie ways, our place is a kind of termite nature reserve, where wood-eating insects can flourish, peacefully ingesting fruit trees and vernacular architecture, without fear of retaliation.  It seems, when they tired of consuming ad-hoc structures made of discarded bed bases, they like to break it up by devouring whole stands of artichokes as a kind of palate cleanser.

Termite eat artichokes – who knew?  Last year’s gorgeous silver leafed statement in the outdoor room is this year a soggy larvae-infested hole in the ground.

But let’s not lose faith in our insect workforce!  We need to reframe this problem. Bill Mollison once consoled someone tending a denuded garden: “You don’t have a slug problem, you have a duck deficit“.  Thinking along these lines let’s put it this way: we don’t have a termite problem: we have a woodwork surplus.

When we first arrived here six years ago, we were puzzled by the gratuitous decking around the washing line and the apparently pointless wooden walkway that took you there.  Our neighbours said they’d scratched their heads as they watched this expensive folly being nailed together.

The mystery was illuminated by the lingering damp patch by the garden gate.  Somewhere between the fig tree and the passionfruit vine, roundabout where the sewage line runs down from the house, there was a persistent and troubling damp patch.  RB wanted to investigate.  Having experienced the delights of sewage tumbling through another backyard and with a terrifying vision of a poo fountain raining down on my veggie patch, I implored him to leave it to the professionals.  But I made the error of leaving him unattended one day after work.

Thankfully I was spared the realisation of my nightmare of e-coli amongst the asparagus.  It turns out our damp patch was an old storm water drain, busted through when the some new and exciting toilet was installed in the house.  As one does, rather than repair the drain and desoggify the garden, our predecessors just built a walkway over the swampland.  What with the convenient supply of moisture, this wooden path has been a fine buffet for the termites over the years.

Thanks to our cellulose loving friends, a short stroll to hang out the laundry had become as fraught with peril as a high-wire walk between two sky scrapers.  Collecting a clean pair of undies from the line carried the ever-present risk of a broken ankle or at least the embarrassing prospect of a plank snapping under your weight, a reminder that you may have had too many marinated artichokes on your pasta lately. Yes, I could have fixed it properly with some decent hardwood or a load of treated timber.  But that just wouldn’t have been in the spirit of the thing.  Instead, it’s become steadily more raddled looking, thanks to running repairs with a random selection of timber found by the side of the road.

But even with my love of hammers and heavy rubbish, I finally had enough.  The walkway had to go.  Even in 35 degree heat, the demolition job was a highpoint of my weekend.  There’s little more viscerally satisfying than ripping something to bits with your bare hands, even if it has been fatally weakened by termites first.

But what to do with the hardwood footings, cemented and bolted in place?  Digging them up would be tricky work, haunted by the ever-present risk of a spade through the sewage pipe.  And then it came to me in a blinding flash: with a bit of help from our termite tenants, moist soil heaped up onto wood frames would do the job for me.

So now the erstwhile walkway is a (very very slightly) raised bed, fenced in by scraggy aviary wire: yet another addition to the carceral complex that is our garden.  As I water the cucumbers and the cherry tomatoes,  I’ll be helping our Willing Workers on Organic Farms Backyards, the termites, demonstrate the second law of thermodynamics.

It’s been a long time since I sat through high school physics.  Things might well have moved on in the inexplicable post-Newtonian world. But I can say with absolute confidence that, in our yard at least, there continues to be “a natural tendency of isolated systems to degenerate into a more disordered state”.

If they weren’t disordered in the first place, the termites, the possums and the brush turkeys would pretty soon make them that way.  Good work if you can get it, lads!

Broken Bay at low ebb

Last weekend I decided to explore the lower reaches of Mooney Mooney Creek from its meeting point with the Hawkesbury, riding on a rising tide. After my spooky solo paddles in Mangrove Creek, I had a hankering for the open horizon and a bit of human life around me. From my put-in at Deerubbin Reserve beside the freeway, and all the way round Spectacle Island, a nature reserve in the mouth of the creek, the constant hum of the traffic and the echoing rumble of trains crossing Brooklyn Bridge remind you that “civilisation” isn’t far away.

Low tide at Mooney Mooney Creek means mud and oyster leases.  The lingering blue haze from last week’s hazard reduction burns descended on the poles and frames, forlorn in the shallows, blurring them into beautiful abstracts.

The story of oyster farming in the Hawkesbury in recent times is a sad one, full of strange historical ironies.

People have been harvesting shellfish from the shores of the river for a very very long time and Sydney rock oyster has been farmed in Broken Bay since the 1880s.  In those days oysters were dredged from the estuary floor and after the meat was eaten, the shells, along with those from ancient middens, were burnt to make lime for mortar.

But in 2004, after a hundred years of farming oysters here, Qx disease hit the Hawkesbury.

The “Q” in the name stands for Queensland.  The Sunshine State produces a 10th of the oyster harvest it did in the nineteenth century, thanks to Qx and to the oyster-infesting mudworm (introduced from New Zealand in the 1880s along with imports of oyster spat). The “x” was a scientific shorthand for “what the hell is this anyway?  We really don’t know”.   Since then, researchers have figured out that Qx is caused by Marteilia sydneyi, a single-celled organism that during the summer infects oysters, causing them not just to slowly starve to death, but also to reabsorb their own gonads (nasty!).  The parasite then releases spores that cycle their way through a polychaete worm, Nephtys australiensis, in the winter, before reinfecting the oysters the following season.

M. sydneyi isn’t always the kiss of death.  The parasite is found in estuaries all along the coast of NSW and Queensland, even in “low risk” areas where Sydney rock oysters are still being commercially grown. Environmental stress, it seems, triggers outbreaks of Qx and surprisingly few wild Sydney rock oysters, the ones I saw lining the rocky shores of Mooney Mooney Creek, die from Qx. Which is good, if mysterious, news.

So, facing of losses of over 90% of the harvest, what could save the oyster industry in the Hawkesbury?

It was noxious pest to the rescue.

The Pacific oyster, farmed in Japan for centuries, was smuggled into Port Stephens in the eighties and spread quickly through the intertidal zones of New South Wales.  It’s a fecund and fast growing bivalve, planktonic eggs and larvae travelling far and wide, crowding, outgrowing, and sometimes settling on and smothering native rock oysters. A “selfish shellfish”, in the words of one inspired Tasmanian subeditor.

The very qualities that have made the Pacific oyster such a hateful invader came to the rescue of the Hawkesbury farmers in 2005.  A process for producing sterile “triploid” Pacific oysters had been developed in North America in the 1980s, with the aim of pumping out meatier shellfish fast. When fertility mean spawning 40 million eggs in a season (not to mention changing sex several times over a lifetime) avoiding reproduction saves a lot of energy.

Local farmers restocked with these “triploid” Pacific oysters.  As well as being immune to Qx, they were ready to harvest in less than two years compared to the three and a half years it takes rock oysters to reach the table.  The new “tamed” Pacific oysters took the Hawkesbury by storm.

And then in 2013 disease struck again. Millions of oysters were wiped out overnight by a virus that affected Pacific oysters and Pacific oysters alone.

Like the oyster itself, the scientifically spawned sterile “triploids”, and indeed the settlers that farm them, “oyster herpes” or POMS (Pacific Oyster Mortality Syndrome), first seen in France in the late noughties, had circled the globe to Broken Bay.

Only three oyster farming businesses are still going in the Hawkesbury these days, hanging on for scant supplies of Qx resistant rock oyster spat, first found amongst the survivors of the Georges’ River outbreak in the mid 1990s.

Right now, the derelict oyster farms are mostly places for posses of pied cormorants to hang out.

But there’s still plenty of life to be found at Mooney Mooney at low water: globe trotters like the eastern curlew, exhausted after a long flight south, and locals like the rock warbler that only lives on Sydney sandstone, compensating for its drab colours and homebody ways with a goth-style nest of grass and spider webs it hangs in the darkness of caves and crevices. And I clocked a new heron record – twenty at least, catching crabs in the mud of low tide.

References

Michael C Dove, John A Nell, Stephen Mcorrie and Wayne A O’Connor “Assessment of Qx and Winter Mortality Disease Resistance of Mass Selected Sydney Rock Oysters” Journal of Shellfish Research 32(3) 681-87 doi: http://dx.doi.org/10.2983/035.032.0309

Wayne A O’Connor and Michael C Dove “The changing face of Oyster Culture in New South Wales, Australia” Journal of Shellfish Research, Vol. 28, No. 4, 803–811, 2009.

J.A. Nell “The history of oyster farming in Australia” Marine Fisheries Review 63(3), 14-25

Love, death and stray cats

It’s not often that I find myself on same page at Tony Abbott, Australia’s climate change denying PM.  But having exhausted the potential of their previous three word slogans, the conservative government recently moved on to a new one: “Kill the Cats”.  After this week’s events I think I could find some common cause with Tones on this theme.

I know you shouldn’t have favourites but Shyla was my favourite chicken.

She came to our place as a bundle of fluff and managed, uniquely, to survive our enthusiastic but doofus chick rearing.  She was the hen you would trip over at the chookhouse gate, where she would be pacing up and down the second the back door opened.  And then she would follow you round the garden waiting for lovely things like grapes or curlworms or weevil ridden comestibles and if none of those were forthcoming, peck your butt to see if it would make an adequate alternative.  Her response to a human approaching was to squat and jiggle in what I think translates loosely from hen as “ok, you can mount me now”.  Which was faintly disturbing, while at the same time suggested an affection of some strange kind.

And that’s not even mentioning the fact that she was our one reliable layer, producing a daily egg all winter long.

Since she was such a useful, friendly and characterful girl, she was obviously the first choice for a midnight snack when a great big feral cat came visiting our yard in the dead of night this past week.  I don’t want to sound callous but the bloody thing could have taken Snowball the silky bantam – smaller, ancient, more visible in dim lighting, huffy around humans, laying eggs only when the weather and the tides are just right.

But no, it had to grab Shyla, the life and soul of the backyard. The Top Chook took one for the team.

Everyone’s very subdued down in the bottom of the garden now, accepting the indignity of being carried, half-asleep, from their perilous perch on the edge of the fig tree barrel, to secure lodgings in Palm Beach, the long-abandoned vernacular modernist chicken coop.

Shyla was the victim of our hubris – the one who paid the ultimate price of six years without locking the chooks up at night.

So what changed in our suburban ecosystem?  I reckon it’s the departure of the (somewhat annoying) little yappy dog next door.  The neighbours on the other side have a laconic German Shepherd who doesn’t even chase the chooks.  But the yapster would have given a cat a run for its money.  If Tony and cronies want to get rid of feral cats, it’s not red-necks with guns that will do the job.  Scientists reckon the best strategy is to restore the top predators – dingoes.  Based on anecdotal evidence – the death toll in our backyard – I reckon they’re right.

With sufficient vigilance we can protect the chooks but we can’t do much for the bandicoot that still noses its way through the veggie garden at night.  Bandicoots recognise dingoes (and dogs more generally) – they know to avoid them.  In fact, some scientists have argued that this makes dingoes – placentals, only here for 50,000 years or so – natives.  But bandicoots still haven’t figured out cats.

I’m trying to find some positives in the situation.  My latest planting of broad beans has sprouted, magically unmolested.  I could attribute this success to my lavender mulch, or to the carefully secured veggie net, or the cold weather that has probably driven the local rodent population indoors (where we live.  Gulp.)  But perhaps the feral feline took a few rats as a chaser after devouring poor Shyla.  It’s a choice, it seems, eggs or beans.  Not fair!  I want both!

It’s all very sad.  Our eight year old got it right as she sobbed herself to sleep the other night: “you know where there’s someone in your care and you can’t protect them, you feel like there’s a hole in your heart”.  Yeah, babe I do.

I’ve been thinking about another lost lovely one this week.  The twelfth anniversary of our son’s death has just passed us by.  Born, unexpectedly, with a lopsided and innovatively organised brain, he was a bonny baby boy, whose plump little body suffered many seizures and would never really do quite what he wanted.  He had a short but lovely life, that ended suddenly and surprisingly (we shouldn’t really have been surprised) before dawn on on a beautiful winter’s morning, just like these last glorious days.

For a time, during the relentless rumination that followed our sleepy newborn’s diagnosis, I spent a lot of time thinking about stray cats.

Stray cats crapping in our pocket sized backyard.  Stray cats with a payload of toxoplasmosis gondii, “one of the most successful parasites on Earth”.  It inhabits the bodies of around half of the world’s human population, and plenty of other warm blooded animals too, but only reproduces only inside pussycats, emerging to infect other creatures, the parasite transmitted through cysts lurking in its poo.

Recently there’s been a pop science fascination with the consequences of toxoplasmosis infection.  While (most of the many many) infected people are asymptomatic, researchers have found that rats with the parasite become risk takers.  Losing their natural fear of cats, some even become attracted to the scent of their predator (not coincidentally, the parasite’s host).  Humans with toxo, too, seems to have somewhat different personalities than those without.  This idea, that humans – philosophers and planet conquerers – might have our very selves shaped by a single celled organism, disturbs and fascinates us.

If you are unlucky enough to be infected for the first time in the early weeks of pregnancy, your baby can be born with congenital toxoplasmosis, with possible serious consequences for the child’s health.  Toxo can cause problems with vision and hearing, seizures and intellectual disability.  Which is why I found myself thinking so long and hard, a decade or so ago, about my lack of gardening gloves and the roaming neighbourhood moggies.

In the end, my ruminations about infected cat shit went nowhere, like the dwelling upon dioxins from the incinerated corpses of foot-and-mouth infected cows that filled the air that year, or my endless Googling on the chromosonal origins of pachygyria (“Come back if you have another one with the same thing” the genetic counsellor suggested.  We were floored.  Although not quite so amazed as when she asked us, the Scotsman and the Australian, if we were cousins)

Very very occasionally Tony Abbott, MP, is accidentally right: sometimes shit just happens.

How do we make sense of these things, the deaths of our beloved children and the untimely demise of our pet chickens?  How are they connected, the miraculous germination of broadbeans and the midnight movements of predators?  The passing of parasites and personality traits from rats to cats to cat lovers?  The hidden life of the soil and the secrets in our bloodstream that can elate us and destroy us, often at the very same time?