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June 25, 2016

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Animal communication, Anthropomorphism, Backyard birds, Gardening, Native birds, Satin bowerbirds, Uncategorized

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R2D2 in black and white

Poseur juvenile magpie

Catalogue model juvenile magpie amongst autumn leaves

I’ve been spending a lot of time with magpies lately. “Model magpies” as my nine year old aptly described these two who spent the day posing in the Japanese maple and prancing around the back deck. Oddly enough, the companionship steps up in intensity whenever I stop typing for a snack.

This gang of youngbloods don’t spend all their time begging for food and doing catalogue shoots, though. There’s also the occasional training session for the Olympic synchronised vogueing competition.

Synchronised posing from juvenile magpies

… And pivot!

… and the querulous look

…. and finally “Blue Steel”

And, of course, plenty of carolling. The juveniles spent a lot of time last week singing for their supper, until one of the grown-ups got jack of the whole thing and flew down to show them how it was done.

But not before the youngsters did their party trick. In amongst all the mellifluous warbling, my ear caught some distinct moments of robotic squeaking and clacking. The magpies were doing a bowerbird impression.

Adult magpie carolling

Two juvenile satin bowerbirds in the bottom of the garden jungle

Apparently Australian birds are uncommonly good at mimicry. Lyrebirds are famous for it, but all sorts of implausible suspects have a line in impressions as well: magpies, mistletoe birds, silver eyes. Apparently the minute brown thornbill has been recorded mimicking a pied currawong – a bird forty times its size.

Brown thornbill vainly attempting to be a currawong

Silvereye

Why do birds mimics the songs of others? Pretending to be something bigger and tougher for self defense purposes seems to be one motive. Bowerbirds have been observed doing raven impressions while being mobbed by a colony of those rather nasty bell-miners, for instance.

Another seems to be showing off to make yourself look good to potential mates. Researchers have found that male bowerbirds that can only manage a one or two rubbish impressions (singing “like a kookaburra with bronchitis”, as the researcher cruelly remarked) have less mating success than those who can effortlessly produce a good five.

The most hilarious explanation I’ve read for bird mimicry is to chill out sexual partners. Researchers reckon that R2D2 style squeaks and clicks that satin bowerbirds make while courting can freak out their mates:

“by interspersing melodic mimetic laughing kookaburra and Lewin’s honeyeater calls between episodes of harsh mechanical calls, males may calm females and improve the likelihood of that females will stay for additional courtship and copulation” (Borgia and Keaghy, 2015)

The idea that a sudden explosion of kookaburra calls would mellow you out and get you in the mood gives me a good picture of why certain male bowerbirds (and possibly particular male ornithologists) might be unlucky in love.

Female (or juvenile) satin bowerbird reaching for pittosporum fruit

Satin bowerbird flying away

Satin bowerbird flying away 2

While not as famous as lyrebirds, bowerbirds do some pretty amazing impressions, not just of individual sounds but of whole acoustic scenes. How’s this, observed from a toothed bowerbird?

A male started with the sounds of a group of people talking as they moved through the forest with their machetes cutting bushes and dogs barking, and continued with the sounds of machetes being used to fell a tree, complete with the rattle of shaking leaves after each blow and eventually the sound of the tree falling and hitting the ground with a crash (Borgia and Keaghy, 2015, 97)

The humble magpie doesn’t do badly either. They’ve been recorded copying 21 different species of bird, as well as the sound of horses, dogs, cats and humans. Magpies, it appears, only imitate critters that share their territory, not just the blow-ins and passers by, so it makes sense that our youngsters copy the satin bowerbirds that seem so spend much of the year in the garden, eviscerating my beans and kiwifruit vines and making free with my broken pegs.

I’ve got a whole new agenda in the backyard now. There’s those in-flagrante males doing kookaburra impressions to listen out for. As yet, I haven’t found any references to magpie calls appearing in the satin bowerbird repertoire. Maybe this will be my contribution to science. Better still, maybe I’ll catch a bowerbird in the act of ripping off a magpie doing a remix of another bowerbird. Or the other way round.

Female bowerbird in our dawn redwood

Mature male with designs on my chilli plant

Additional references

Borgia, G. and Keaghy, J. (2015) “Cognitively driven cooption and the evolution of sexual displays in bowerbirds”in Irschick, D., Briffa, M and Podos, J. (eds) Animal Signalling and Function: an integrative approach, Wiley Blackwell

Kaplan, Gisela (2015) Bird Minds, CSIRO Publishing

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mccnmatt

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May 13, 2016

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Geology, kayaking, national parks, Native birds, natural history, Uncategorized, waterways

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Delta bravo!

Kylie’s Beach in Crowdy Bay National Park

It’s lucky that travelling in reverse is just as easy as going forwards in Egg, my decrepit wooden kayak (currently held together with duct tape), because lately my paddles seem to be taking me back in time. Back to old haunts and old holiday snaps, but also really really far back into the geological past.

When I took this photo of beautiful Kylie’s Beach in Crowdy Bay National Park in 2011, for instance, I wasn’t thinking “My, what a fine example of a barrier dune system in a wave dominated estuary!”

Diamond Head and Watson Taylor Lake

And this snap from North Brother Mountain, taken on the same trip five years ago, demonstrates that I wasn’t paying enough attention to geomorphology at the time. It’s not a bad shot of the 100,000 year old Pleistocene sand barriers that protect Watson Taylor Lake from the crashing waves of the Pacific. But, in retrospect, I should have given the picturesque tree on the right the flick, and made sure I squeezed in a view of the mouth of the Camden Haven River.

Because, for the New South Wales anyway, this is a pretty special place. As you can see in the pic below by a more geologically literate photographer, enfolded in the lake is a classic river delta – a rare sight in this part of the world. It’s a mini-Mississippi, sloughing off its sediment as it flows into stiller waters, leaving muddy banks along the way and a cluster of little islands at river’s end.

Watson Taylor Lake. Bias, Gene. watsontaylorlake.jpg Pics4learning July 2004. 9 May 2016 <http://pics.tech4learning.com>.

Sad to say, I didn’t notice all this deposition and composition as I paddled down Camden Haven Inlet at dawn, skimming over the seagrass and the sand. Even when I got stuck in the mud – sorry, fluvial sediment – right in the middle of the lake. At high tide. Next to a bunch of knee deep swans. Sometimes I reckon I’m not the sharpest knife in the knifeblock.

Black swans smirking while I try to get afloat after running aground in the middle of the lake

It was only back at camp at Kylie’s, over a first reviving brew-up, when I stumbled on Rod’s Northern Rivers Geology blog with its intriguing story of the missing coastal deltas of New South Wales that I figured out what I’d seen.

South Brother Mountain in dawn light

Up a shallow side creek towards the lake

South and Middle Brother from the northern shore of the lake

A side view of the levees beside the Camden Haven River

Paddling dead casual-like towards the river mouth

Thinking back, I realised I’d been somewhere very similar just a few weeks ago, in another one of the New South Wales’ magical coastal lagoons. Where Dora Creek – home of freakish panda-snakes – empties into Lake Macquarie, the very same levees march, both sides of the river, far out into the open water.

Dora Creek doesn’t have mangrove topped islands at its mouth, like the Camden Haven. Perhaps their beginnings were washed away by the waves that scoot across five kilometres of open water to scare the hell out of unwary kayakers. In the same way storms, waves and the East Australian Current sluice river sand and sediment out into the Pacific or up the coast, leaving barrier beaches in place of river deltas all along the Eastern seaboard.

Island in the delta

But in the sheltered estuary of Watson Taylor Lake I got to enjoy all the rare pleasures of a river delta. Mosquitoes, for instance. More than I’ve encountered anywhere, even my backyard, locally famous for its blood buffet and chubby and contented microbats. With the mozzies come the mozzie eaters.

“Clumping” white-breasted woodswallows

Woodswallows peeping

Woodswallow grooming

I stopped to take pictures of the wood swallows, but in fact, this little beach, at the very end of the Camden Haven’s levees, had almost as many birds as it had bugs. Honey-eaters in an array of colours: brown, striped and yellow-faced. Noisy friarbirds, mobs of them, bursting from the casuarinas to wheel and chatter. Wagtails and fantails. Crested terns chilling out away from the surf. A drongo (I’m not being insulting – it’s a gorgeous bird). Not to mention a special treat – the rarely sighted fungus-faced thornbill.

Egg on “bird watching beach” near the mouth of the Camden Haven River

Spangled drongo

The rarely sighted fungus faced thornbill

Crested terns sticking their tongues out at me.

And, as I wended my way through the maze of islands with the help of the handy map in my Paddlers Guide to NSW, an unflappable young sea eagle, rising majestically above the cloud of biters. It takes a genuine love of raptors to continue taking snaps while half a dozen mosquitos are sucking on your eyelids.

White bellied sea eagle in a river-side casuarina

Juvenile white bellied sea eagle

But as RB just reminded me, if Australia’s eastern coast is wanting for river deltas now, it’s not always been so. It was an enormous braided river delta, like the Amazon or the Ganges that laid down the golden Hawkesbury sandstone, a couple of hundred metres thick, right across the Sydney Basin, 230 million years ago.

Perhaps this is an approach to marketing I can put to the NSW Tourist Board. “Volcanos! Dangerous megafauna! Epic braided river deltas! Go back far enough in time, and New South Wales has it all!!”

Reflections of North Brother Mountain on my way back to the put in at Camden Inlet

More adventures on New South Wales’ coastal lagoons

Geomorphology and dawn reflections on a midwinter lagoon at Myall and Narrabeen Lakes

A paddle across scary Lake Macquarie to see the snake-pandas of Dora Creek

Encounters with eagles on Budgewoi Lake

Moonlit night on Kylie’s Beach

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April 16, 2016

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kayaking, Native birds, Uncategorized, Waste, waterways

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What do you get if you cross a snake with a panda?

The geometric art on the Australasian darter’s back

Things I learned from last weekend’s paddle from Lake Macquarie’s Shingle Splitters’ Point to Dora Creek:

1. When kayaking on the largest permanent salt water lake in the southern hemisphere, always remember fetch. Fetch can defined as the distance of open water over which wave-creating winds blow. Where does the word “fetch” come from, I hear you ask? From the cries of sinking kayakers as they disappear behind the white tops: “Fetch the emergency services!”

(Don’t be deceived by the apparent smoothness of the lake surface here – once the wind picked up I was too busy thinking about staying afloat to take any pictures)

Heading across Lake Macquarie from Shingle Splitters’ Point

2. The lyrics of Kenny Rogers’ immortal song “The Gambler” don’t just apply to card sharks, but also amateur bird photographers. “You never count your money when you’re sitting at the table. There’ll be time enough for counting when the dealing’s done”.

Because the few seconds you spend checking to see if that wildly optimistic over-the-shoulder shot caught the hunting osprey mid-dive, will be ones in which the hungry raptor wheels around and splashes down again, right next to your boat. And flies off before you can get the lens cap off your camera.

Departing osprey

Darter near Brooklyn

Female darter near Marramarra Creek

Male darter by Milson Island

Male Australasian darter at Apple Tree Bay

Male darter at Speers Point

3. While adult Australasian darters are the most sinuously elegant of birds, poetry in snake-like motion, their offspring are actively disturbing.

Juvenile darters near the nest

Closeup of the absurd faces of juvenile darters

What is it about these baby darters? They’re very very fluffy. Like a gorgeous soft baby panda. A delightfully fluffy decapitated panda with the head of a snake. A sweet duo of snake-panda in a nest white-washed with guano. And they didn’t think much of me either.

Juvenile darter expressing themself through the medium of guano

In South America, they’ve found are darters in the fossil record that weighed 17 kilos – more than eight times as heavy as these not-insubstantial characters. Just imagine how unnerving it would be in a kayak under that humungous reptilian chick when it let fly.

There’s no danger of modern darters – anhinga to give them their formal name – vanishing like their massive forebears. Like humans, darters like deep, still water not choked with vegetation, as long as there are overhanging trees to nest and perch on. And they don’t mind introduced fish like carp and perch, so they’re doing better than birds that prefer marshy wetlands or are fussier about their diet.

A few weeks back, my brother and I watched with a fine male hunting from the shore of Lake Macquarie in the golden light of the late afternoon. Even after the bird vanished below, we could follow its progress by the tiny fry that leapt from the water. The sinuous head reappeared moments later, a fish impaled on its beak. It took him a few goes, but finally he managed to flick it into the air and gulp it down.

Male Australasian darter trying his wings by Lake Macquarie

Darter skewering a fish

Darter about to fling a fish in the air

Male Australasian darter with a fish impaled on its beak

I’ve seen plenty of snake birds, as they’re sometimes called, over the last couple of years as I’ve paddled around the lower reaches of the Hawkesbury and the rivers and lagoons along the Central Coast. Familiarity hasn’t dulled my enthusiasm for them – the males geometric abstracts, the females russet in the sun, their elegant necks holding poses as striking and absurd as those of modern dancers. But I’ve never seen the young ones before.

Darters breed erratically, it seems, whenever and wherever conditions are good. They will fly long distances – up to 2000 ks in the non-breeding season – and will nest inland when floodwaters linger. Maybe the stretch of Dora Creek where I saw them is a regular breeding spot. In one fecund tree I saw two empty nests, along with two brim full of snake-pandas and guano. Or perhaps the vacant real estate belonged to other waterbirds, since darters seem to like to nest in company. Down the river, egrets, cormorants and partly-fledged juveniles were hanging out on a branch together, not far from this perturbed looking male with his runaway egg.

Casuarina with four waterbird nests

Male Australasian darter on the nest with a runaway egg

Partly fledged juvenile Australasian darters

Greater egret in a suburban front yard by Dora Creek

One way or another, the younger chicks seem to prefer intimacy to solitude, finding comfort, as they crouched in their absurdly flimsy nest, in the softness of their siblings’ breasts and the predatory encircling of each others’ snakey necks.

Three darter chicks snuggling crop tighter

Juvenile Australasian darters snuggled together in what remains of their nest

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April 3, 2016

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Death, kayaking, national parks, Native birds, pollution, Predators, Uncategorized, waterways

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Death and good fortune on Cowan Creek

Since reading the poetic prose of H is for Hawk, Helen MacDonald’s story of how training Mabel the goshawk carried her through wild sadness that followed the death of her beloved father, it’s been all about the raptors around here.

Easter at Speers Point meant ospreys relaxing in the late afternoon sun.

Osprey with eye gleam for crop horizontal

And yesterday, on Cowan Creek, the contractual obligation white bellied sea-eagle.

Juvenile white-bellied sea eagle

“Peach Trees” – or peregrine corner

Sandstone patterns in Yeoman’s Bay

White-faced heron hunting at Yeoman’s BAy

Then, just when I’d resigned myself to a pleasant if uneventful paddle after three hours on the water, there was an explosion of action right off my bow. Two birds in an aerial battle, tumbling and squabbling over a kill. The loser flew off, disgruntled; the death-dealer pulled up in the bright morning sunshine on a branch over the river, and waited for me to get out my camera.

Peregrine falcon in profile with prey

Peregrine staring straight at the camera

Peregrine gripping a dead galah and looking for rivals

A new bird! One I thought I’d never seen on any waterway. A peregrine falcon.

It turns out I had seen these birds before, long ago and far away – a pair tussling with ravens over a ledge to nest on at Malham Cove in Yorkshire. Cliffs (or, if they are hard to find, skyscrapers) are one of the essential requirements of this beautiful raptor. RB reminded me that peregrines used to nest in the ventilation towers of the tunnels under the River Mersey and high up in the Liverpool’s Anglican Cathedral, the enormous red sandstone building I could see from my desk during my decade as a Scouser.

Peregrines may be the most widespread bird in the world, living on every continent except for Antarctica and on many islands (although strangely, considering its status as a bird watching paradise, not New Zealand). Its name is derived from the Latin for “the wanderer” although only five of the nearly twenty subspecies – those breeding in the northern Arctic – really migrate very far.

For all their capacity to adapt to life in the city – eating feral pigeons and nesting in highrises – peregrines are widespread but not really common. Since they mostly prey on smallish birds, themselves often insect eaters, falcons bioaccumulate pollutants. The use of organochlorines in insecticides like DDT devastated their numbers in the second half of the twentieth century. By the 1960s there were no peregrines in the Eastern US and the birds were declared an endangered species. Numbers have bounced back, in Australia and elsewhere, although they are still classed as “rare” here. And recent work in Europe and Canada has observed a new chemical – flame retardants – turning up in the blood stream of peregrine chicks.

Peregrine mid-dinner, beak covered in feathers

Once peregrines find a good nesting site, it’s a keeper. Apparently, a falcon skeleton found at the back of a cliff-top eyrie in Tasmania has been carbon dated at 19,000 years, which makes that spot the oldest known bird’s nest. As I noodled along the northern shore of Cowan Creek, I’d admired the 100 metre high cliffs of Looking Glass Spur, eucalypts halfway up the face finding impossible footholds in the sandstone. I wonder if my falcon and its mate have a scrape there, high above the expanse of the estuary. Peregrines don’t eat fish but hunting grounds by water offer the space for their deadly turn of speed.

I feel less disappointed by my failure to spot the raptor’s stoop or to capture the battle on film after I figured out what I was watching. The fastest animal in the world, dropping on its prey at nearly 400 kilometres an hour. That poor bird clutched in its talons -maybe a galah, the favoured meal of the big-footed Australian “macropus” subspecies – never had a chance.

Peregrine eating a galah

Peregrine falcon’s tongue on display

I watched for twenty minutes, as she plucked and dismembered her meal, unperturbed by the rowdy parade of jet skiiers, cruisers and powerboats. Galah feathers drifted down from her branch, making a delicate trail of death across the bottle green water.

For a few dodgy moments, I thought the gobbets of galah might be joined by flotsam from my shattered craft as Egg was washed perilously close to oystershell sharpened rocks. And, if I had the Bond-style rocket launcher I’ve often fantasised about while ploughing through powerboat wakes on sunny Sunday mornings, fragments of several jet skis.

Peregrine falcon plucking its prey before eating it

Peregrine falcon “macropus” showing off its huge feet

Trail of feathers from the plucked galah

Remnants of the plucked galah

I’m guessing my peregrine was a “she”. Females are a third bigger than the tiercels – the males – but I didn’t have the chutzpah to hurl a swiss army knife up the tree for scale. The two mid-air combatants looked well matched – two males or two females. Definitely not a pair. Since peregrines mate for life – up to 20 years – and often hunt cooperatively, it would seem to be unwise from the point of view of domestic harmony, anyway, to bicker over food.

In fact, Derek Ratcliffe describes exactly what I saw: “feet-grappling over disputed food items” which happens, he says, “at food-territory boundaries during the non-breeding season” (1993, 201). It seems these battles are nearly always between birds of the same sex, although sometimes peregrines fight with other crag-loving birds as well. RB remembers peregrines in springtime at the cliffs at Creagh Dhu, attacking ravens, stooping then zooming straight up to the heights to do it all over again. Sometimes pairs of peregrines will even take on the great golden eagle over rare and valuable real estate.

So maybe there’s more than one pair of peregrines on that beautiful bit of country. Perhaps I’ll see this magic bird again, or her mate, or her rival, until I’m as blase about a peregrine strike as a whistling kite soaring on a thermal. But yesterday, as I took my four hundred photographs while the peregrine peaceably disembowelled its meal, showing the equanimity that makes them the favoured hunting falcon, I felt truly blessed.

Peregrine in front of branch staring at me crop

Peregrine falcon watching the watchers

More stories about raptors in Berowra’s backyard (and mine):

The beautiful white morph of the grey goshawk in Bluetongue’s back

A hunting collared sparrowhawk in Nude trees and naughty birds

The whistling kites of Bar and Peat Islands in Two sad islands, three whistling kites

The many white-bellied sea eagles of the Hawkesbury and Lake Macquarie in Encounters with eagles

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March 30, 2016

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Backyard birds, kayaking, national parks, Native birds, Seasons, Uncategorized, waterways, Weather

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The silver river

Mist and silver river … somewhere behind there is the Wreck of the Parramatta

Deerubbin – the Hawkesbury proper- doesn’t normally look like this: not when I’m there, anyway. I’m used to the view out our back window: the valley full of fog, the hilltops islands in a foamy sea.

Mist over Sam’s Creek

You know the fog will be spilling across the highway as you swoop down from the ridgeline before dawn. But when you reach the freeway bridge that stretches half a mile across the Hawkesbury, the wind picks up and the mist is gone.

But not this Sunday. The cloud was down and the river was silver.

Fisherman in the mist

Misty sun above Grace’s Shore

Peat’s Crater with silver gulls for scale

Looking towards Grace’s Shore

I’ve wrestled with this mist before.

I can say with confidence it’s not freezing fog, hail fog or upslope fog. For all the salt in the air, it’s not coastal fog – moisture condensing over cool water – not with sea temps a balmy 24 degrees. And is it valley fog? Damp cool air might slide down the hills in the night… but Sunday’s haze followed midnight downpours not clear skies.

Having thought about it rationally and analytically, I can only conclude that this was magical fog, sent to stop me paddling all way to the secret heart of this part of the Hawkesbury, Marramarra Creek.

Mist over over mangrove saplings for horizontal shorter

Big Bay

Mangroves in Big Bay at high tide

Skies over Big Bay

I’ve nearly made it there before, as far as Big Bay, with its great lagoon full of mangroves and the riverbed chocabloc with critters. No houses on the ridgelines, no way in except by water. In the 1830s a surveyor’s wife didn’t think much of it: “these dreary solitudes might serve for the abode of a misanthrope so utterly are they secluded from all approach and so entirely destitute of all comfort”. But I’m longing to paddle all the way to the source of the creek, through country with an indigenous past even I can read.

But this time it wasn’t just the fog and the march of time that stopped me. The birds were in on it too, perching photogenically on the wayside oyster poles, feathery sirens luring me away from my upriver odyssey.

Sirens on oyster poles

Demure crested tern

Pelican and boat

Pelican in flight

Small pied cormorant pretending it’s a gull

Pied cormorants on oyster poles

So I’ll have to come back to Marramarra. Maybe next time I’ll bring our full flotilla of mismatched craft and camping gear and stay overnight halfway up the creek in the old orange orchard. The noisy kids should to scare away the temptations of the sirens… and, of course, the silvery silence. So perhaps I’ll follow Odysseus and bring some ear plugs too!

Striated heron hunting on Bar Island

Milson Island in the mist

Egg returns past Bar Island

Looking north on the Hawkesbury from near Deerubbin

Related posts – other paddles on the Hawkesbury from Deerubbin Reserve

Two sad islands, three whistling kites: a paddle from Deerubbin to Bar Island

Of gods and mapreaders: a trip up Kimmerikong Creek in Muogamarra National Park

A bridge fetishist paddles to Brooklyn: paddles up Mullet Creek and around Dangar Island

Broken Bay at low ebb: a short jaunt around the oyster beds near Spectacle Island at the end of Mooney Mooney Creek.

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March 7, 2016

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Animal communication, Animal senses, Backyard birds, Lizards, Native animals, Native birds, natural history, Uncategorized

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Thinking like a bird

One of the things I love about my regular walk to the the train station is the chance to check out the critters’ daily routines while I’m in the midst of mine. I’m an everyday intruder, just passing through. Through the carpark behind the panel beaters’ shed where the glossy black cockatoos do their acrobatics. Over the slimy patch on the footpath that used to lure eastern waterdragons out to play chicken in the traffic (I stress “used to”. Sad face). Past the carefully tended brush turkey mound in the scrub by the library and round the the blind corner where butcherbirds find their roadkill. So far I’ve never seen them pecking at the flattened remains of kids on skateboards but I worry.

Eastern water dragon

Alley-oop

Upside down glossy black-cockatoo

I was trudging home a few months ago, when there was a kerfuffle in the shrubbery that even the most self-absorbed commuter couldn’t ignore. An aggravated bird was repeatedly hurling herself at an invisible enemy, and making a tremendous din. I spotted a tail sliding behind the trunk of a halfway up a tree – was it a goanna? a snake? No, a brush-tailed possum, having a late afternoon snack in a grey butcherbird’s nest. Mum was willing to fight for her eggs to her last breath. I don’t have any pictures of the stramash, unfortunately, despite roaming around Berowra most days like some bumbling stalker, a chunky camera swinging around my neck.

However, I feel a bit less sheepish about my amateur-hour suburban birdwatching – and a little less clueless about butcherbirds – after reading Gisela Kaplan’s fascinating book Bird Minds (CSIRO, 2015) this week.

Grey butcherbird makes a rare appearance in the backyard

Bird Minds considers most aspects of avian cognition – social learning, mimicry, tool use, play, abstract thought and emotion – with a particular focus on the locals. This, as Kaplan points out, is no mean feat. Aussie natives are under-discussed in the world of scholarly ornithology, it seems. She tells (with secret delight, I reckon) how the international community were forced to reluctantly accept that songbirds evolved in the part of Gondwanaland that came to be Australia, overturning 200 years of northern hemisphere prejudice. The oldest songbird fossil ever found came from here, and recently the discovery of heron footprints from the Cretaceous Era in southern Victoria showed that birds and those other, non-avian dinosaurs cohabited this part of the world, at least, for millions of years.

So, as well as summarising the work of researchers from around the globe, to fill the gap in the published research on Australian natives, Kaplan draws on anecdotes from bird watchers (like the amazing tales of fire-starting black kites that have done the rounds in the papers lately) and her own experience of studying, observing and hand-rearing birds over the decades. My particular favourite is her story of the adopted 75 year old galah who liked to summon all four household dogs by name in a passable impression of Kaplan’s voice just for the fun of bossing them around. Every week. It’s this kind of jolly jape that keeps a bird young.

Pair of galahs

Butcherbirds are just the type of birds that Kaplan is interested in, although her own research for the last 25 years has been on another member of the Artamidae family, the Australian magpie. Currawongs, butcherbirds and magpies, like many other Australian natives, don’t fit a northern hemisphere perspective on avian lives. Grey butcherbirds are wonderful mellifluous singers, for example (though their tunes are less feted than the improvisational outpourings of the pied butcherbird). But their carolling doesn’t fit the familiar songbird story.

Kaplan points out, for instance, that while northern hemisphere songbirds are most vocal during the breeding season, the Australian bush is often quietest at that time. Amongst the much studied birds of high latitudes, males sing as part of a courting display. In comparison, she observes, “Australian species often seem rather ‘egalitarian’ “. For many Aussie birds, including butcherbirds “there is often no difference in the song between male and female, no marked difference in plumage or size, brooding and feeding of youngsters and defence” (Kaplan 2015 114). I have to confess, this whole line of argument really appeals to me.

Magpie in spring

I also get sneaky pleasure at Kaplan’s observations about the cleverness of Australian birds. Smarts, she suggests, are one strategy for coping with harsh environments and unreliable climatic conditions. The humble budgie, a desert dweller, for instance, has one of the largest bird brains for its size, along with Cape York’s palm cockatoo, a formidable tool user. These clever cockies select, shape and stash particularly excellent sticks, some to use as percussion instruments and others to improve nest-hole drainage. Behavioural flexibility is a sign of sophisticated thinking: I guess musician cum plumber fits that bill quite nicely. Birds like this, Kaplan thinks, playful, inquisitive and social, fill the ecological niche of monkeys in an Antipodean environment.

Australian birds often live much longer lives than their northern hemisphere equivalents. Permanent pair bonding means that galahs, for instance, or sulphur crested cockatoos may end up in a 60 year partnership. Kaplan suggests that these long-term pairings require social nous and a sophisticated communication repertoire. Forget relationship counselling, it could be time to take advice from the local cockies!

Nuzzling sulphur crested cockatoo

Lovebirds

What are you looking at?

Young Australian birds are also likely to spend a long time hanging around with their parents learning the ropes – an extra year for grey butcherbirds, as much as four for white-winged choughs. Which explains the whiny teenagers I’ve been hearing everywhere lately.

It’s hilarious watching great hulking juvenile wattlebirds, indistinguishable from adults to my untrained eye, sitting in the Japanese maple tree out back, calling plaintively and endlessly for parental attention until someone hops up and gives them a lerp. And last week on the way home, as I passed Butcherbird Corner, I heard the sounds of a youngster calling out that all-too-familiar refrain: “Mum! Mum! Mum! Mum! Mum! Mum!”. It drives me mad when my kids do it, but on this occasion, pester-power put a smile on my face. The lumbering youngster was a survivor of the Possum Bloodbath of 2015, demanding quality time (and a take-away) from its weary parent.

Little Wattlebird on alert

Little wattlebird in the backyard

Juvenile grey butcherbird

The youngbloods may hang around with mum and dad for ages, but they do get off the couch and help with the housework. Raising your chicks with the help of older siblings and even unrelated adults – “cooperative breeding” – is surprisingly common in Australia, in comparison to elsewhere. If refraining from tearing your life-partner limb from limb with your own beak during the course of 60 years together is a challenge to a bird’s emotional control, how much more so is long-term living with the extended family?

This is an idea that Kaplan toys with throughout the book – that “negotiated living” might “require… changes in powers of perception: a watchful eye, powers of observation and careful scrutiny of others… watching others means awareness of others and such habits can change from behaviour reading into mind reading” (Kaplan 2015 122). Complex social lives go along with complex minds.

I rather enjoyed the sly dig at northern hemisphere birds (they sound nice, but could well be dim) that runs alongside Kaplan’s argument for the evolutionary value of cooperation.

in the competitive mode, learning (in males) is for a well-rehearsed performance: an Eistedfodd of dance or song. In the cooperative model, learning is for communication (Kaplan 2015 119)

Old leftie that I am, I can’t help liking the idea that cooperation, “egalitarianism” of the sexes and general smarts go along together.

Long beaked corellas giving me a funny look long.jpg

Long billed corellas giving me a funny look

I can’t vouch for the rigor of Kaplan’s science, but I loved reading her stories of the cleverness of Australian birds – their “versatility, resourcefulness, complex social and individual problem solving abilities” (Kaplan, 2015, 193). Reading Bird Minds has given me plenty to look out for as I make my workaday way through the suburban territory we share.

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February 19, 2016

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Anthropomorphism, Geology, national parks, Soil, Uncategorized, waterways

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Alhambra on the Hawkesbury

The last few times I passed by Bujwa Bay, on my way downriver from Berowra Waters, it was shrouded in mist.

On the way to Bujwa Bay

Mist blowing out of Bujwa Bay

A misty morning on Berowra Creek

But last Sunday, in the golden light of late afternoon, there was a revelation.

I’m familiar with the Hawkesbury’s sculpture parks and sandstone art galleries. But the fact that Berowra Creek had well preserved fragments of an ancient Moorish fortress – well, that was news to me.

The “sculpture park” on the northern shore of Long Island, the Hawkesbury

River rainbow, in Berowra Creek

Honeycomb formations in a cave above Bujwa Bay

Sandstone art gallery in Smith’s Creek

When I went home and told RB I’d seen something very like the famous stucco inscriptions of the Alhambra on a estuarine cliffside at the end of Berowra Waters Road, his comment was “You’re barking!”. And he’s probably right.

Honeycomb weathering in sandstone on Bujwa Bay

After all, the Alhambra is an artistic jewel, a masterwork of European Islam, preserved over the centuries after the Moors themselves were driven first into the mountains and then out of Spain altogether. Its delicate carved plasterwork miraculously survived Christian conquerors, dodgy architectural restorers, squatters and tourists. And the sandstone of Bujwa Bay is just, you know, rock.

“The sea” in the Alhambra

Stucco inscriptions

The Alhambra from a distance

Stucco and tile in the Alhambra

Stucco inscription at the Alhambra

But I’ve been reading about “thing power” and it’s given me a whole new angle on inanimate objects. “Thing Power!” – sounds like a killer bathroom cleaner that will sort out all the disturbing life-forms, named and unnameable, in your shower cubicle.

But according to Jane Bennett, its “a creative not-quite-human force capable of producing the new [that] buzzes within the history of the term ‘nature’ ” (2010, 118). Electrons, microbes, minerals, waste, all busily making and shaping things, inside, around, through, against and despite humans and their fancy-pants plans. She reckons things and people rub along or against each other in a pattern that’s “not random or unstructured, but conforms to the strange logic of vortices, spirals and eddies” (2010, 118).

Alveoli weathering in sandstone

Stone lacework on Bujwa Bay

Kooky as it sounds, this is not a bad description of how the Bujwa Bay Alhambra came into the world, according to a paper coauthored, in a way that pleases my penchant for magical thinking, by a geologist from Granada, home of the famous palace.

Honeycomb weathering like this happens in all sorts of porous rocks, around the world – from Antarctica to Jordan – and maybe even on the surface of Mars. It might seem like hollows would form in weaknesses in the rock, but it’s not necessarily so. Blistering heat, frost, chemical weathering and rain are all in the frame – with maybe a little help from the odd patch of algae or lichen. But mostly it’s about salt and wind.

Salty water – in this case from seaspray – seeps into the rock and crystallises, making tiny fractures. If there’s plenty of water, salt crystals forms on the outside surface to form efflorescence, a mineral flowers blooming on a cliffside or a cellar wall or a garden fence. But the real damage is done deep in the rock.

According to Rodriguez and friends, once a depression is formed in the rockface, wind eddies and swirls inside the concave parts of the stone. Faster breezes mean more evaporation and a super-saturated salt solution, meaning more salt crystals and more fretted stone. Eventually the rockface becomes lacework, without any intervention by a rock lacemaker.

Alhambra rocks 1 crop long

The other name for honeycombed rock is alveoli. It’s stone with lungs. Made of mineral flowers. Not alive (or mostly not alive – sorry algae) but doing complicated and beautiful things.

Not immortal, invisible, unfathomable. In fact, as fathomable as the waters of Bujwa Bay at low tide, that is, knee deep to a heron. Just exceedingly hard to grasp.

And that’s not just me banging my head against a corroding brick wall of “Salt weathering: a selective review” – the geologists are still bickering over exactly how it works. In Bennett’s (possibly slightly loopy) words, it’s vital matter, “hard to discern… and, once discerned, hard to keep focused on. It is too close and too fugitive, as much wind as thing” (119). Or perhaps, in this instance, both wind and thing.

A crab wondering what I’m on about, on a beach near Bujwa Bay

References

Jane Bennett 2010 Vibrant Matter, Duke University Press

Eric Doehne (2002) “Salt Weathering: a selective review” from Natural Stone, Weathering Phenomena, Conservation Strategies and Case Studies. Vol 205, 51-64, Geological Society Special Publication

Carlos Rodriguez-Navarro, Eric Doehne,Eduardo Sebastian (1999) Origins of honeycomb weathering: The role of salts and wind, GSA Bulletin; August 1999; v. 111, no. 8; p. 1250–1255

Huinink, H. Pel, L, Kopinga, K. 2004 “Simulating the growth of tafoni” Earth Surface Processes and Landforms 29 1225-33

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February 11, 2016

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national parks, Native birds, snakes, Uncategorized, waterways

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Snakes vs whining teenagers

Tiger snake curled face crop long This is what people who hate camping think it’s all about, right? I suspect spiders, high winds and rowdy neighbours also make that list. Yep, a big tick next to them too – it’s all to play for when you camp in the summertime in Wollemi National Park.

But Ganguddy, or Dunn’s Swamp, to give its inaccurate and charmless non-indigenous name, was just as marvellous this January as it was when we first visited this time last year.

Ganguddy in early dawn light

Dew on some kind of orchid?

Lichen on native cyprus

Dawn at Ganguddy

Purple flower

Leptospermum flowers

Strange club shaped lichens

Dusk at Ganguddy

View from the pagoda lookout

Yes, there were more reptiles – lethal and benign – but to balance it out, there was also less torrential rain. At no point this year did it seem likely that the full set of adult campers, each clinging to a leg of the kitchen-gazebo, would take off and fly over the pagoda rock formations like a quartet of grubby Mary Poppinses. It rained, but not inside any of the tents. And the whining teenagers weren’t my delightful children but the feathered offspring of the camp ground locals.

“Feed me!”

“Where are you?”

Juvenile noisy friarbird wants a snack

It seems a bit unfair for such giant children to be demanding food, although Gisela Kaplan in her fascinating book “Bird Minds” suggests some evolutionary advantages to having hungry teenagers hanging around. Apparently adults noisy friarbirds only feed the young’uns for three weeks after fledging -hard to believe this galumphing one was so close to being a fluffster.

But you can see where all that food goes. You reckon your adolescent’s feet are big? What about junior purple swamphen‘s clodhoppers?

Juvenile purple swamp hen with giant feet

Adult swamp hen feeding the hungry bairns

Unhygenic as it sounds, the drop dunny seemed to be a particularly popular spot for a snack. The baby grey fantails spent a lot of time looking deliberately cute there in order to get a feed. If you were still uncertain about the superiority of the earth toilet, this little guy is a clincher I reckon.

Juvenile grey fantail hanging around the drop toilets

“I’m hungry”

“Please feed me – I’m cute!” – juvenile grey fantail

The white-browed scrubwren also enjoyed loitering out around the toilets. I didn’t see any juveniles, but then this one looked so stern, perhaps they were there but just too nervous to beg for tucker.

Grumpy looking white browed scrubwren

The suspiciously touselled looking eastern yellow robin – a juvenile perhaps – had worked out that the best place for tucker is definitely the barbecue.

Eastern yellow robin having a picnic

Eastern yellow robin

I’m not sure if the adult reed warbler had gone into head down, bum up, to feed some chicks, or if it was just going to extreme lengths to avoid facing the long-lensed papperazzi. I was rather pleased when after two years of trying I finally got a picture of one, without even having to visit the Rylstone Guns and Ammo for a flame thrower to thin out that pesky, snap obscuring habitat.

Reed warbler nest

Reed warbler

And, miracle of miracles, I found an azure kingfisher without ADD. I reckon I can put away my paddle now – 18 months of kayaking have not been in vain.

Kingfisher on stump 2 instagram square.jpg

At last – a sluggish azure kingfisher

The invasive gambezi minnows that fill this reservoir – built in the 30s as a water supply for a concrete works – seem to be an optimal snack size for the kingfishers – I saw plenty of them, along with a randy musk duck, the ubiquitous Eurasian coots and a pair of Nankeen night herons that alighted, mockingly, in the trees opposite the campsite, just after it got a tiny bit too dark for a decent photograph. But there was nothing larger – no whistling kites, for one. Judging from the frustration level of the fisherman in our party and the track record of these mosquitofish of outcompeting native rivals, I suspect there weren’t many more substantial meals to be had (on the bright side, possibly thanks to the fish, there weren’t too many mosquitos making meals of us either).

Musk duck courtship display

Musk duck tail on display

With all these LBBs – and all the fast moving ones I didn’t get a decent shot of – busy flocks of brown thornbills high in the canopy, white-throated tree-creepers spiralling their way up the tea trees, the baffling grey strike-thrush, the white-eared honeyeaters darting around in the dew drenched dawn – I guess I shouldn’t be surprised at the snake that sidled through the camp site or or the one slithered along the ironstone tops. Let’s hope the top predators were more successful at catching the flighty little buggers* than I was.

Rock formations near the dam

Currawongs at the camp site

Tiger snake on ironstone?

Red bellied black snake in the campsite

Sandstone and lichen

More sandstone and lichen

Silhouettes of the camp site trees

Dawn over “Swallow rocks”

*Okay I know red-bellied blacks mostly eat frogs, which is why they were down by the reedbeds near the camp. But I bet they don’t object to the odd gormless yellow robin if it’s available.

* * *

There’s more info about the history and geology of Ganguddy in my previous post from here: In other sandstone country

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February 5, 2016

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History, kayaking, national parks, Uncategorized, waterways, Work

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A bridge fetishist paddles to Brooklyn

I have a weakness for bridges. Romantic trysts just happen to be arranged with the backdrop of the world’s first iron bridge. Multiple crossings of the gorgeous Severn Suspension Bridge are absolutely essential for that work trip. And in pride of place of the mantlepiece, of course, is a railway poster of the famous cantilever bridge over the Firth of Forth.

So perhaps it’s not surprising that my paddles lately all seem to end up under what it pleases me to call Brooklyn Bridge. That’s not its real name, mind, but since it starts on Long Island and takes you through the thriving metropolis of Brooklyn (population 744) I think I can get away with it.

Brooklyn bridge and stone pillars plus boat.jpg

There was that morning jaunt from Parsley Bay, past the oyster leases and beneath the swooping welcome swallows, to the top of Mullet Creek, where the Newcastle trains disappear into the Woy Woy tunnel, once the longest tunnel in the southern hemisphere.

I’ve been lucky enough to go on on some beautiful railway journeys in my life – from Montreal to New York in winter, past above-ground swimming pools frozen like giants’ ice-cubes; from southern Thailand to Bangkok, looking out at the richest of tropical orchards woven into the jungle; between snowcapped mountains and sea on the West Highland line to ~~Hogwarts~~ Mallaig. But I reckon this journey along Mullet Creek, not a place that will ever be immortalised in the baby names of the rich and famous, is my favourite. There’s something about a railway line that leaves roads far behind, forging its own way along the empty shore.

Sunrise at Brooklyn

Looking back at the Hawkesbury River Railway Bridge and Long Island from the mouth of Mullet Creek

Freight train going up Mullet Creek

“You looking at me?” – pelican at Parsley Bay

If you ask the driver, you can get off near the top of the creek at Wondabyne, the only station sans road access in Australia. Every now and then, you see people jumping off the train and straight into a tinnie, zooming off to the shacks on the other side of the river before their fish supper gets cold.

For a few years in the late nineteenth century, while the first Hawkesbury River bridge was being built, if you were travelling north by train from Sydney, you would disembark at Long Island, board the double-decker paddleboat the General Gordon, and steam off to Mullet Creek Station, then just north of Wondabyne. Now people hop off here to do part of the Great North Walk – a 250 kilometre walk from central Sydney to the beautiful beaches of Newcastle – or to wander up to Pindar Cave. Judging from the smorgasborg of rusted out craft I saw in the shallow water at the top of the creek, it’s also a place where people take their boats to die.

White jellyfish in Mullet Creek

Barnacles on a wrecked ship in Mullet Creek

A boat that may well be beyond repair

Then there was this weekend’s jaunt, downriver from Deerubbin Reserve – a popular spot, right by the freeway, to fish or have a picnic for those who find the perpetual roar of traffic reassuring. With the ever present possibility of a quick exit, I guess it’s ideal for the heavily pregnant or those who find their relatives a bit hard to take. But I can’t really bag people for their passion for the internal combustion engine since I get all hot and bothered at the prospect of a paddle underneath (count ’em) three great big bridges.

Sunrise over Long Island

Three bridges in early morning light: the freeway bridge, the Pacific Highway bridge and the Brooklyn Bridge

Hawkesbury River Bridge in dawn light

This weekend’s jaunt took me past Spectacle Island Nature Reserve, under the Hawkesbury River Railway Bridge, natch, and around Dangar Island, swished along smartly by the current and the falling tide.

Have you ever been bored enough in an airport to try walking the wrong way up a moving footpath? Trying to paddle across the current to get to one of the beaches on the eastern side of the island was a bit like that. It all seemed a bit too hard in the end, so I went where the river wanted to take me, downstream, floating just above perilous rocky reefs by off Bradley’s Beach and veering round the seagrass beds.

Sailing boats north of Dangar Island

Hawkesbury River Railway Bridge at dawn

White boat, blue hills at Kuring-gai National Park

And then through the sailing boats, swaying and tinkling like expensive marine windchimes, to Sandy Bay, the best place in the world to be homeless. The folks whose setup I saw there – a tarp flanked by a beached ramshackle boat and a solar panel – had no-one for neighbours but a horde of blue soldier crabs. There was no sign of the human residents, but I now know what it’s like to be a celebrity, thousands of beady eyes watching and waiting on your every move.

Quite a few people live rough around Brooklyn. “Good caves, a shower at Brooklyn Baths and walking distance to the bottle shop”, as RB commented with unseemly enthusiasm. In the Depression, apparently, lots of people came to live in these parts for just this reason – shelter and a bit of space for chooks or a veggie garden. I didn’t see a chicken run in Sandy Bay but Brooklyn does seem to have some kind of common flock, judging from these good looking fellas that we met down by the marina a while back.

Egg at Sandy Bay

Chickens on the commons at Brooklyn

A floating barn at Parsley Bay

Thousands of blue soldier crabs watching me

Blue soldier crab

I reckon the Hawkesbury estuary is Sydney Harbour through the looking glass – a parallel flooded river valley, bordered by bush instead of multimillion dollar apartments. If the Harbour has its iconic Bridge, the Hawkesbury has its own engineering marvel – nearly three times as long, resting 50 metres and more deep in soft black mud.

The modern bridge is the second one to cross the river here. The old bridge, finished in 1887, was the last link in the railway that spanned four colonies, connecting Queensland to South Australia.

Sir Henry Parkes, on the day of the bridge’s official opening, pronounced: “In this great system of material arteries which we completed today, we see the crimson fluid of kinship coursing through all the iron veins” (Sharp, 2001, 4). Apparently the other grandees were a bit more underwhelmed by the prospect of a federated Australia, bound together with railways. Nonetheless, the day after, the headline in the Sydney Morning Herald was headline was “United Australia”

Bridge silhouette 1

At the time it was built, the old bridge was the longest in Australia and had the deepest footings in the world – 180 feet below the high water line – though they still didn’t reach solid ground.

The Union Bridge Company from New Jersey won the contract to build it (on a pin-jointed truss system, as I’m sure you want to know), giving Brooklyn, the railway town that was set up to house the workers, its American name. The tender being won by an American company was one in the eye for the old country, though it pleases me in some strange way that the riveted steel for the spans was made by Arrol Brothers in Glasgow, who also worked on the bridge across the Firth of Forth.

The Hawkesbury River Railway Bridge from Long Island

The old Long Island Railway station

White faced heron checking out the engineers’ work on the new bridge

But the original Hawkesbury River Railway Bridge didn’t last. Its piers, filled with rubble instead of solid concrete, fractured under the weight of the trains that crossed here, the only bit of duplicate track on the line. The piles were starting to crack in the 30s, but the problem only came to light when a US railway geek doing a bit of light recreational reading of an engineering textbook spotted that the piles weren’t built to the original specifications. The death knell of the old bridge, though, was the extra rail traffic of the war.

The piers of the old bridge remain, like golden castles guarding the river.

The footings of the 1887 Hawkesbury River Railway Bridge. Or castles as I like to call them.

I’ve had a great time reading the fantastically detailed history of the building of the new bridge by Major-General Albert Cecil Fewtrell, the Chief Civil Engineer of the NSW railways, who supervised its completion.

There’s some entertaining reading between the lines. When it came to putting the metal spans onto the concrete footing, it seems some fool had a plan to float the 1,600 tonne metal spans over to the pilings at water level and then haul them out with giant cranes perched on the piers. But Major-General Fewtrell soon sorted them out:

“Consideration had been given early to the proposal to float out the spans at low level … The decision [was made] to revert to the high level method of floatation following the return of the Author from active service in 1943” (Fewtrell, 1946, 27)

The cuttings made for the construction docks for the 1946 bridge, and the boat that’s now doing bridge repairs.

The prep they did for the task of floating the massive spans from the construction docks – the cuttings still visible on the north shore of Long Island – onto the concrete pilings at high tide also gives you a sense of the guy.

A large board, representing the land and water at the site of the new bridge, was laid down in the southern tunnel. Model piers were accurately fixed in position in the “stream,” and miniature spans, pontoons, and equipment were used so that the men could practice in detail movements and prepare for emergencies.

Don’t you want to play with those 1/32 scale tiny cranes and miniature pilings? I really really do.

Fewtrell thought that everything had gone swimmingly. But the new bridge, the bridge that was supposed to last 200 years, is crumbling. After years of delays, just this last week, work started on repairing the concrete footings and its rusting reinforcing steel. When I paddled past, there were huddled men in high vis jackets and mysterious icons dangling from the bridge deck – all the signs that a new engineering miracle is about to begin. And I’m sure it’ll happen.

But at this stage, once again, I reckon it’s Hawkesbury River 1: human engineering 0.

Work starts on repairing the Brooklyn Bridge

Number 7 pier – the tricky one to get into place

Signal near the new bridge work

The elaborate connections between the pier and the span of the new bridge

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January 22, 2016

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Fruit, Insect pests, Plants and what I know about them, Possums, Rats, Uncategorized, Vines

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Experiments with kiwifruit

Thanks to exhaustive if faintly intrusive matchmaking with a ladder and a paintbrush back in October, we have a bumper crop in the kiwi arbor.

Pollinating kiwifruit

Kiwifruit buds and flowers

The kiwifruit harvest

Four years ago the northern wall of the kitchen was occupied by a dank lean-to, usable only for turning your bike into the kind of rust-bucket that can be safely left overnight at train stations. But we don’t need these kinds of amenities. If you leave your bike unlocked outside the pub in Berowra, it might get taken by a drunk on his wobbly way home, but if it does, the bartender will recognise the miscreant on the CCTV footage and leave a friendly message on the guy’s answering machine to return it in the morning. Even the pelotons of MAMILS leave their featherlight carbon-fibre bikes untethered at the end-of-ride coffee shop.

Blue skies over Berowa

So, with no need for a bespoke bicycle corroding zone, we replaced the corrugated iron over the frame of the lean-to with couple of precociously fruitful Sweetie kiwifruit vines, a low chill variety from Daleys Fruits in Maleny. Last year we had a handful of fruit that the possums seemed enjoy. If they’re planning to eat the whole crop this year they’d better be hungry.

The laden kiwifruit arbor

Who’s been eating my kiwifruit?

Peeping possum looking innocent

I’m feigning disinterest in what happens to my kiwi harvest but let’s be real – the last few years have turned me from a lentil-eating hippie into an antipodean Mr McGregor, the pointlessly enraged gardener who would love to turn Peter Rabbit and his fluffy little brothers and sisters into a delicious warming casserole.

Don’t get me wrong, while I do covet the infinitely soft possum-fur jumpers that vengeful New Zealanders knit from our invasive marsupials, I’m not spending my nights under the kiwi trellis with a gun in my hand. That said, the rugby-league style gum shield I wear overnight to stop me grinding my teeth to dust (expensive, but since it doubles as a contraceptive, probably good value) does date from about the time I started trying to grow fruit in the backyard.

No, I’m taking a less brutal and more scientific approach to harvest-management. I have a control – the fruit I’m leaving untouched on the vine. And I have two intervention groups – there’s the kiwis I’ve picked early, hard as furry brown rocks, and left to ripen in the fruitbowl, and then there’s the bunches I’ve put into protective custody in mesh exclusion bags.

I maintain a cautious optimism that I will get to eat at at least some ripe fruit. This upbeat attitude has nothing to do with early success. While commercial kiwifruit are usually picked unripe and can be kept on ice for two months or more, so far my early harvest has withered slightly but maintained a mouth puckering acidity, as evidenced by our school holiday Ph testing activity.

I can’t seem to kick the habit of growing red cabbages, despite the fact that no one in the house, myself included, really wants to eat them. They’re just so pretty!

Red cabbage abstract

So apart from feeding the leaves to the cabbage white butterflies that my 9 year old keeps in her bedroom as “pets”, what else can you do with leafy brassicas too chewy for coleslaw? Well, you can boil them up and use the purple cooking water as a very cool litmus test.

There’s nothing kids like more than squeezing out half the toothpaste tube, making potions out of bicarb, tomato sauce and milk, or filling every single glass in the kitchen with disgusting viscous liquids. We even ended up with a boys v girls Ph contest – boys obviously preferring alkaline household products, while as we all know, historically girls inevitably favour acids. Including our long-cossetted kiwifruit, which turned our cabbage water a pleasing deep pink.

The results of the purple cabbage litmus tests

Early indications are the mesh exclusion bags aren’t doing much better than the fruit bowl in the protection and ripening caper. I can’t remember a pre-masticated fruit being present when I tied the bag around this bunch. We seem to have a Houdini of the rodent world somewhere on the premises. The outcome so far is not as dismal, at least, as 2014’s doomed attempt at protecting peaches. The mammal and insect pests deployed a pincer movement – rats gnawing a hole in the bags and fruitflies pouring through to finish the job.

Intervention group 1: ripening in the bowl

Intervention group 2: inside the exclusion bag

No, my optimism about getting to wrap my laughing gear around some home-grown kiwifruit sorbet is based on the barely nibbled fruit discarded the ground under the vines. Whatever is chowing down on my crop just isn’t very keen. Perhaps they have a sweet tooth.

How, I hear you ask, can you tell when to harvest your kiwifruit? Well, apparently if you cut one open and the seeds have turned black it’s ready for harvest: its starches will turn slowly to sugar in storage. But there is a more scientific way. Sugar solutions refract light, particularly polarised light, differently from your ordinary tap water. So your go-to-device for measuring sweetness (reported in Brix) is a refractometer. The savvy kiwi farmer picks her fruit at a bit over 6 degrees Brix, it seems. Let’s just hope the brush tailed possums can’t tell their pouches from their polarising light and the satin bowerbirds couldn’t track down a refractometer on ebay.