Warbling in lockdown

Kayak on still river water at dawn with reflections showing the sky

Six weeks into a Sydney lockdown.  Everyone confined to their homes with occasional outings for food and exercise no more than a few ks away.  I feel super lucky that this bit of Dyarrubbin still falls within the 10 k radius I’m allowed to stray from my house. Berowra Creek, at the end of my street, is super quiet at the moment, the houseboats rocking empty at their moorings, jet-skis banished – only the locals heading out in ones or twos for some fresh air.

It seems fitting that the “feature wildlife” of my escape to the river last weekend was also a local – Sydney’s only endemic bird, origma solitaria, the rockwarbler.

These little birds are only found within 250 km of Sydney, hopping around mostly on Hawkesbury sandstone, though I’ve hear they also pop up on the limestone and granite, where it is to be found.  Their range on the coast extends from Mollymook  to Raymond Terrace, and they can be found as far west as Orange and in the north can be found up in the beautiful Coolah Tops National Park, according to the CSIRO Australian bird guide favouring “exposed, dissected rock outcrops…from coast (including sea cliffs) to high plateaus  of the ranges” (2017, 340).

Rockwarblers are not uncommon – despite their restricted range they’re flagged as of least concern, conservation-wise – though they don’t appear to inhabit cities like Newcastle, Sydney or even Wollongong or Nowra.  On my noodling 12 k paddle last weekend I spotted one pair busily feeding and nestbuilding on rocks by the waterside, and then, having tuned my ear to their high pitched calls, spotted another pair doing much the same, on the return journey.

I don’t see them on every trip out but I’ve observed them behind golden beaches on Cowan Water and in rocky bays near Dangar Island, and even in one of the spots  at Berowra Creek with the most foot traffic, at Washpool Creek where the Great North Walk meets the estuary.

The rockwarbler is an unremarkable looking little bird – “a small, plump, dark brown-grey bird with a cinnamon-tinged face and forehead, a dull white throat speckled black, reddish-brown underparts”, almost the definition of the LBB – but has some interesting habits.  It makes pendulous domed nests that hang in darkened overhangs and caves in the rocky terrain it prefers – apparently its common name used to be “hanging dick”.  Who says all folk wisdom  needs to be kept alive, eh?

I spotted my first rockwarbler for the day collecting what looked like nest material – roots and possibly spider webs  in the exposed root system of toppled trees on the shoreline. She flew off intermittently into a group of boulders behind some casuarina trees – I couldn’t get a clear shot of the crevice she seemed to be returning to, so no photo of a hanging dick, for which you might well be grateful.

Despite all this, I’d like to get a glimpse of a nest – the description in Birdlife’s online site have a hard core goth appeal:

Made from grasses and plant fibres and coated with spider webs, [the nest] is attached to a rocky overhang or roof of a cave by spider webs, which the bird hammers into place with its bill. They are then covered with saliva to hold them in place

You can see in these pictures that the spot I saw my first pair of rockwarblers has been a important place for humans as well as non-human animals for thousands of years.  The soil here is thick with oystershells, left by the custodians of this country over the centuries, and now woven into the earth in scores of places right along the shores of Berowra Creek.  Everywhere you look around here there’s a midden.

Rockwarblers look a little bit like northern hemisphere robins and seem to have a similar outgoing personality – “confiding” in the words of the CSIRO blue bird book.  This bird and its mate, that soon arrived on the scene, didn’t seem particularly disturbed by a kayaker loitering nearby with a camera, and I managed to drift quite close while they scoured the rocky shore for largely invisible food.

I’ve read that rockwarblers are primarily insect eaters although Carol Probert has reported seeing nectar drinking in some she watched in the Blue Mountains. No evidence of this here but there seemed to be plenty to eat.  This pair traversed the rocks briskly, picking mysterious things from amongst the moss, and even dipping beaks into the little bowls comprised of previously-opened mollusc shells on the rocks.  I’m not sure  if the rockwarblers were scrounging for critters that had found a home in these tiny rockpools.

There were plenty of insects about in the lee of the rocks, but i didn’t see any of the birds I watched that morning snatching a snack from the air, despite the temptation.

What I did see – once with each pair of birds – was what I think were nuptial gifts – one bird feeding the other snack, perhaps with romantic intentions.  I stress I did not witness any subsequent feathered intimacies but with birds you blink and you’ll miss it, so that doesn’t necessarily mean a lot!

Here’s pair number one, coming beak to beak.

And the second pair

I think I can see a insect leg sticking out from the crumb in the beak of the bird with the tuft of feathers on its back.  I guess these scenes could have been adults feeding juveniles, which look similar to the grown-up rock warblers, only paler in colour, but I didn’t hear any pitiful calls from the recipients and given the time of year – roundabout the beginning of breeding season for many birds – a romantic gesture seems a bit more likely.

The rockwarblers were pretty friendly to me but also to the other little birds hopping around the nest area, particularly a family of variegated fairywrens that seemed to follow them as they hopped about round the edge of the water.  The warblers kept their feet mostly on rock, the wrens mostly flitting from twig to twig in undergrowth nearby. If there’s dietary competition between these little birds, it’s a very friendly one.

In fact, I suspect this was more like the mixed-flock foraging that have been noticed in many parts of the world in wintertime, when different species of small insectivous birds move around feeding as a group.  Maybe the rockwarblers’ hopping stirred up some flying insects for the wrens to eat?  Some researchers have found that variegated wrens, sometimes hang out with “friends” from other species whose territory overlaps with their own, sharing the defense of that territory, travelling and foraging together. This benefited the wrens a lot – they “spent more time foraging, were less vigilant [and] had greater first-nest fledging success” (Johnson, 2018, 821).  I wonder if the wrens were as friendly as this with my rockwarblers?

The atmos not so friendly amongst the waterbirds feeding nearby.  I watched a whitefaced heron repeatedly asserting dominance over a striated heron on a sequence of estuarine patches, as I trekked back the put-in.  Berowra’s ubiquitous waders are higher up the pecking order than ubiquitous lurkers it seems.

And then, just as I turned the corner to the marina, high over all, the alpha local of these lands.   A wedgie soaring silently, surveying its domain.

 

References

Davis, William M and Recier, Harry “Winter mixed species foraging flocks in acacia woodland of Western Australia” Corella, 2002, 26 (3), 74-79
Menkhorst, Peter; Rogers, Danny; Clarke, Rohan; Davies, Jeff; Marsack, Peter; Franklin, Kim The Australian Bird Guide, 2017 CSIRO Publishing
Probets, Carol ; Palmer, Grant ; Fitzsimons, James “Nectarivory in the Rockwarbler ‘origma solitaria’ Australian field ornithology, January 2019, Vol.36, p.34-35
Smith, Peter ; Smith, Judy “Re-use of a rockwarbler ‘origma solitaria’ nest over a 13-year period” Australian field ornithology, 2012-06-01, Vol.29 (2), p.77-82
Other locals in our backyard

The trouble with the younger generation

It’s not often that the stars are in alignment for a midweek paddle but occasionally it happens.  Children elsewhere, being forced to make music for 48 straight hours; the car (or “kayak transportation device” as I prefer to call it) sitting there unused and no pressing work engagements before 9 am on a Wednesday morning.

Berowra Creek was delightfully quiet, save for a handful of tinnies bearing estuarine commuters towards the wharf and the road to the big smoke roundabout 7 o’clock.  I guess that’s rush hour on the Hawkesbury.

Ferry lights closer crop

Pre-dawn rush at the Berowra Creek ferry

A peaceful river, low tide… time for the shy critters to come out of the mangroves and feast in the mud.

Juvenile Striated heron hunting silhouette with catch brightened

Juvenile striated heron with a tiny fish

I go past the mouth of Joe Crafts Bay quite regularly.  It’s a magical place, blessed with reflections and rolling fog, and a secret creek filled with darting fish.

Towards Joe Craft bay

Looking to Joe Crafts Bay on a misty day

I’m always expecting to see something exotic there, like the critically endangered Eastern Curlew, visiting Australian coast during the northern winter after an epic migration from Russia and western China.   Mostly I see bird-shaped sticks.  But on this quiet morning, what I initially suspected to be a stick turned out not one, but two striated herons.

Juvenile striated heron profile in water 2 amended darkened

Juvenile striated heron pretending no one is looking

It’s pretty unusual to get a good look at these birds, described on one twitcher website, unnecessarily cruelly I think, as “a dumpy little heron with a large head“. Or if you were really mean you might describe it as a dumpy little heron with a jack-in-the-box neck.

Juvenile striated heron alarmed lightened 2 amended square

Juvenile striated heron with neck stretch

I normally spot striated herons only after I’ve already bugged them enough to burst out of their hiding places in the mangroves and fly off, disgruntled, down the river.

Striated heron stretching

Adult striated heron perching at high tide

They are not given to making a lot of noise and hunt stealthily, perched on a low branch over shallow water or creeping along the shoreline looking for little fish, crabs or crustaceans.  Interestingly, they sometimes also fish with bait – dropping a feather or leaf on the water to lure fish to the surface to investigate.  These birds seem to be quite smart  – researchers have even recorded youngsters playing with bugs, fruit and pieces of wood – perhaps practicing for bait fishing.

But for all their creativity, young herons like most juvenile birds, seem to be a little bit slow on the uptake when they unexpectedly encounter a mammal in a boat.  And long may that stupidity continue.

Juvenile striated heron from behind square and lightened

Pensive looking juvenile striated heron

There was also an adult bird on this particular mudflat, clever enough to stay a lot further away.

adult striated profile crop

Adult striated heron, macroryncha subspecies

And while the adult wasn’t incredibly impressed with me being in its territory, it was really very pissed off that it was having to share its patch of low tide real estate with a young heron.  According to the International Union for Conservation of Nature’s Heron Conservation group – an impressively specialised body – African striated herons are so determined to defend their territory that you only find a couple of individuals in a 13 kilometre stretch of river.  Our aggro Aussie adult, true to form, went after the youngster no less than three times while I was watching, chasing it off the prime spots on the mudflat with real venom.

Adult straited chasing juvenile crop long

Adult striated heron chasing off a juvenile off his feeding grounds

Not so the adult could hunt.  Oh no. Youngster was finding fine pickings.  But having cleared him out, the adult heron did this:

Nada.  Played a game of statues. Or maybe pretended to be a stick for the benefit of nosy kayakers. It’s always pleasing to see birds behaving as expected.  Here we see an “adult… freez[ing] when disturbed; standing motionless with their bill… at 45 degrees

I was surprised to find that the striated heron, shy and retiring as it is, has been described as “one of the more cosmopolitan herons“, which suggests somehow it has well-used hand luggage tucked away in the mangroves somewhere and frequent flyer points.  Sub-species (in an attractive range of colours) are found right around the world – from Africa, Madagascar, the islands of the Indian Ocean, East Asia, and South America.

Adult Striated heron walking toe out good pattern

Adult striated heron stepping out

Australian striated herons – both the east coast macroryncha, grey with perhaps a flush of wine colour on its underparts, and the reddish-brown stagnatilis which living in the north west – are a bit fussier than many overseas subspecies, living pretty much exclusively in coastal areas in and around mangroves. That’s quite different to the rarer but to my untutored eye somewhat similar looking black bittern that is found along forested rivers, like the Wyong River where I spotted this one, and even rivers much further inland.

If you’re kind of fussy about where you live, Joe Crafts Bay seems a tremendous place to end up.  No wonder the grumpy grownup wants to keep it to himself.

Magic Joe Craft Bay

Joe Crafts Bay at its magical best

 

More adventures on the Hawkesbury

A visit with the eagles of Mooney Mooney Creek

Magic scenes on a cold and foggy day on Cowan Water

The silver river – up Marramarra Creek

Of gods and map readers – into Muogamarra National Park

Two sad islands, three whistling kites – a visit to Barr Island

Burnoff at Bujwa Bay

Alhambra on the Hawkesbury

 

 

 

The river that knew

Mist and sky above Mooney Mooney Creek better

Looking upriver from the junction with Floods Creek

If I want a quiet morning on the Hawkesbury, my best bet is a paddle up Mooney Mooney Creek.  It’s a jet ski free zone, and that’s a very fine thing. In maybe ten jaunts on various reaches of Mooney Mooney, I’ve seen a handful of kayaks, a few fishermen and one very slow moving yacht.  Unlike Cowan Creek or Patonga, there’s no sandy beaches for frisking about on, and the oysterfarms can be navigational hazard at low tide. But if you prefer hanging out with eagles and herons to spending time with humans in charge of powerboats, Mooney Mooney Creek’s the go.

Azure kingfisher profile crop

An uncharacteristically still azure kingfisher

There are really three Mooney Mooneys, for my purposes anyway.  There’s the upper reaches, a pleasant morning’s paddle if you throw in tranquil tributary Flood Creek, lined with casuarinas and decorated with the blue and green streaks of kingfishers hunting (more on the scenes and ecosystems there in a future post).  The put-in for that trip is where the switchbacking Pacific Highway crosses the river, though if you paddle upstream you pass under the highest bridge in Australia, a symphony in soaring concrete.

Or you can go downstream, towards Lemon Tree Bay and maybe on a low-ish tide, see, on every bend and mudflat herons feasting, and if you’re lucky, spot a wedge-tailed eagle soaring overhead.

Herons in parallel back in focus

White faced herons hunting at low tide

Up there in the headwaters, you’ll often see other kayakers – there are sometimes guided tours to the area – and occasionally people camping, rather naughtily, by the side of the river.  The Great North Walk, that links Sydney and Newcastle, via most of the lovely places along the way including Berowra (of course), flanks the upper reaches of the river and once or twice I’ve heard voices of hikers walking along the track or crossing the suspension bridge that spans the top of Piles Creek.

Snake island backlit 3

Snake Island and Brisbane Water National Park

But I’d prefer to be paddling than driving and I’m a little bit lazy, so I usually put in my boat in closer to home, at Deerubbin, where the freeway crosses the Hawkesbury.  From there I paddle under the freeway and past Spectacle Island, stopping off to check out the Mooney Mooney spoonbill colony, and then upstream.  Once you get past Snake Island and Sailor’s Chest Point, there’s not much sign of human activity, apart from oyster poles.

But there’s plenty going on, even without too many of us humans around.  Last week’s outing was particularly rich in feathery encounters.  A masked lapwing family enjoying a day out by the water by the Mooney Mooney public wharf.

Comedy silver gulls ducking for crabs in the shallows near Spectacle Island.

Silver gull with crab square amend

A sacred kingfisher  in the morning sun near her burrow in an abandoned arborial termite nest.  She got so bored with me clicking away she had a nap.

A striated heron, one of the river side regulars, pretending to be a particularly striking bit of sandstone.

And further up the creek, the predictable but still wonderful sight of a pair of young sea eagles perched amongst the mangroves in the shallow waters of Fox Bay.

The young ones seem to be easier to get close to.  A bit curious and a bit clueless, perhaps, about strange legless creatures that float downstream with the tide.

Even in the peace and quiet, there’s a feeling that all the inhabitants of Mooney Mooney Creek know about us.  They know we’re there – mostly out of sight, maybe, but not entirely out of mind.  The freeway passes just behind the ridge much of the way up the valley. You see it as you pass Snake Island, the trucks and cars  appear briefly, lifted above the rocky escarpment.  Sometimes, further up the creek,  the wind shifts and you can hear the sound of the traffic.

I recently found out that the freeway’s original route went right through my tranquil paddling territory – along Pile Creek, to cross the river south of where the Pacific Highway runs.  Right through kingfisher country.

But someone in the National Parks and Wildlife Service in the late 60s or 70s stood up to the road builders and just said “No”.  No, you can’t build a bloody great big road right through the (then recently established) Brisbane Water National Park.  We’re not having it.  In the words of the surprisingly fascinating “OzRoads” website

This new route had a more expensive bridge and steeper grades than the preferred route but there was nothing the DMR could do about it.

And it’s not often you hear freeway builders say that.  I’d love to  know the full story of who in Parks fought the good fight with the Roads folk.  Everytime I paddle up Mooney Mooney Creek now, I’ll be thinking about them and saying a little thank you.

Sea eagle facing away profile crop

Other paddles from Deerubbin Reserve

Up the Hawkesbury to Bar Island

For the ambitious, further in the same direction to Marramarra Creek

Into the heart of Muogamarra National Park up the winding Kimmerikong Creek

Downriver under the gorgeous if structurally challenged Hawkesbury River Bridge

 

Further references

Boon, Paul (2017) The Hawkesbury River: a social and natural history CSIRO Publishing

 

 

Burn-off at Bujwa Bay

The only trouble with living in paradise (apart from the long commute) is combustibility.  Our gorgeous view – mile after mile of incendiary eucalypts.  So the still, dry days and nights of autumn were thick with smoke, not from the big bad one we’re dreading, but hazard reduction burns in the bush all round the town.

Last time I went down to Bujwa Bay, it was the kind of cool and breathless day that must make the Rural Fire Service very very happy.   Mist hovered over the water in a bright line of morning light.  Forty minutes of silent paddling past the sleeping celebrities of Berowra Waters and I was round Oaky Corner and into the sunshine.

In the quiet there was a cryptic crunching noise.   Eventually, I spotted the pair of glossy black-cockatoos hidden amongst at the shore-line casuarinas.  My sense of being some kind of bird whisperer evaporated when, after fifteen minutes fooling around trying to get a decent shot of the cockies, I looked up to meet the eye of a bloody great big white-bellied sea eagle sitting directly above me.  And then, just round the corner, his pal taking in the rays.  They’re not stupid these birds, parked in the sunniest spot on the bay.

Having bonded with the local bird-life, when I heard about the burn-off, I was worried.   What happens to it all when the bush goes up in smoke?

Bujwa bay wide view 2 best small

Egg the kayak entering Bujwa Bay after the burn-off

Drooping bark and grasstrees for crop square

Back-burnt grasstrees at Bujwa Bay

It’s not all bad news.

Harry Rechter describes  birds enjoying a feast during a controlled burn in Brisbane Waters National Park, not so far from here.
“Although fuel loads in the… heath and woodland were high, and flames soared above the tallest trees and shrubs, birds moved easily in front of and above the fire to appear minutes later on the blackened vegetation to feed on less fortunate insects and small lizards”.
I missed the raptors and the insectivores that no doubt turned up at Bujwa Bay at the first sign of smoke, looking for Cajun-style chow. But chances are these blackened grasstrees will be bursting into flower next time I paddle by.  I might see lyrebirds too, raking newly formed clearings.  Ground-feeders and grain-eaters – corellas for instance – return in force after fires have passed.  The little insectivores – thornbills, wrens and robins – that build nests close to the ground don’t miss the scorched canopy, and enjoy the bugs that flourish on the flush of new growth.  The carbonised shrubbery might even give me the chance of catching a blurry LBB or two on film.
Burnt crown and cliff

After the burn-off: partly scorched eucalypts

It’s a nice idea to think that the burn-offs that protect the town are a boon for the local plants and animals too.   And there’s a euphonious catchphrase that goes with that idea: “pyrodiversity begets biodiversity”. Fire incinerates the garden escapes and wakes the soilbank’s astounding store of dormant seeds. If we burn little and often, it’s been thought, we make a mosaic of habitats: patches of open space and newly germinating seeds; places burnt a few years back; and refuges long unburnt, full of craggy trees, hollow logs and dense undergrowth.

Pyrodiversity is popular amongst land management folks, and there’s some evidence that it works, at least in some places.  But not everyone buys the story that the frequent fires that protect people and property suit other critters too. Out in the mallee, near where I grew up, a fire and biodiversity project run by Deakin and LaTrobe universities has been laboriously checking the idea out.

For all the mallee’s underground lignotubers, ready to reshoot after fire, other parts of the ecosystem – large stretches of spinifex grass, for one, that shelter dragons and legless lizards – can take fifty or more years to return after a burn.  All of which makes me feel tremendously guilty about the swiftly abandoned spinifex-covered cubbies that my brother and sister and I used to make in the mallee scrub out the back of our house.  We will never know how many now-extinct species we displaced.

Away from regrets about the trail of ecological devastation I left in childhood and back to burn-off related angst. The research in these arid areas suggests it’s not pyrodiversity that’s important for a species-rich environment but having enough country that’s reached the right stage of maturity since the last fire.  As a person in mid-life, it pleases me to say that older vegetation often seems to sustain more species of birds, mammals and reptiles, including the rare ones. Even birds that like paddocks and open plains prefer unburnt land.  Some reptiles favour recently fired landscapes, but plant communities that haven’t been burnt for a decade or two harbor the richest variety of lizards and snakes.

I tried and failed to find the experts on biodiversity and fire on Hawkesbury sandstone.  But researchers studying both subtropical Queensland and foothill forests in Victoria said similar things.  A varied landscape is important, but

the richness of frugivore, insectivore and canopy forager assemblages is driven by the presence of structurally complex vegetation and old-growth canopy trees, which are more likely to be present in areas that have not experienced fire for a prolonged period of time (Burgess 2016)

Paston and colleagues put their conclusion bluntly: “prescribed fire is of little utility for the broadscale conservation of biodiversity” (2011, 3238).

And it seems, for birds at least, smaller patches of unburnt country won’t really do – it’s larger areas that haven’t seen fire for a while that are rich in species.  One bunch of researchers found that little islands of older habitat surrounded by new growth was grabbed by one or two aggressive predatory or colonial birds, rather than harbouring lots of different critters.  One recent paper, written about arid areas, sum it up:

Our results suggest a shift in current fire management thinking… is needed, away from a focus on creating small, unburnt patches towards preserving large, intact, unburnt areas (Berry 2015 493)

Burnt crown and dark silhouette from distance

What does all this mean for Bujwa Bay?

There was nothing moving in the incinerated trees on the ridgeline as I made my way up the creek at high tide, but then, it was early and damn chilly.  Even the herons had given up on fishing and were huddled in the trees, keeping their feet dry.

But the damp fringes of the mangroves were alive with silvereyes and yellow-faced honeyeaters, and I heard the plunk of a sacred kingfisher diving for breakfast.  Gullies are especially valuable habitats for birds at the best of times.  If they’re protected from fire by burning on the slopes nearby they can be an even better retreat when that big one comes.  The top of the creek was lush and green. I can only guess that the rangers and RFS know what they’re doing.

White faced heron in tree 2 square

Chilly looking white-faced heron

In the light of recent research, Taylor and his colleagues comment dryly “current fire management for avifaunal conservation may require substantial refinement” (Taylor, 2012, 525).

But let’s not fool ourselves.  Around here at least, fire management is not for the avifauna.  It’s for me, and people like me, who choose to live high on a hill, surrounded by the beautiful, burnable bush.

Additional references.  Because the whole thing is really is quite complicated and you might want to check I didn’t get it totally wrong.

Berry, L. Lindenmeyer, D, Driscoll, D. (2015) “Large unburnt areas, not small unburnt patches, are needed to conserve avian diversity in fire-prone landscapes” Journal ofApplied Ecology Vol 52 Issue 2

Burgess, Emma, and Maron, Martine (2016) “Does the response of bird assemblages to fire mosaic properties vary among spatial scales and foraging guilds?” Landscape Ecology March 2016, Volume 31, Issue 3,pp 687–699

Doty, A., Stawski, C, Nowack, J., Bondarenco, A. (2015) “Increased lyrebird presence in a post-fire landscape” Australian Journal of Zoology 63,9–11

Hope Ben (2012) “Short-term response of the long-nosed bandicoot, Perameles nasuta, and the southern brown bandicoot, Isoodon obesulus obesulus, to low-intensity prescribed fire in heathland vegetation” Wildlife Research 39(8) 731-744

Korczynskyj, Luke and Byron B. Lamont (2005) “Grasstree (Xanthorrhoea preissii) recovery after fire in two seasons and habitats” Australian Journal of Botany, 53 509-515

Kelly, Luke T. Andrew F. Bennett, Michael F. Clarke, and Michael A. McCarthy (2015) “Optimal fire histories for biodiversity conservationConservation Biology, Volume 29, No. 2, 473–485

Lindenmayer, David B., Wade Blanchard, Lachlan McBurney, David Blair, Sam C. Banks, Don A. Driscoll, Annabel L. Smith and A. M. Gill (2014) “Complex responses of birds to landscape-level fire extent, fire severity and environmental driversDiversity and Distributions 20, 467–477

Nimmo, D, Kelly, L., Spence-Bailey, L, Watson, S.J. Taylor, R.S., Clarke, M.F and Bennett, A.F. (2012) “Fire Mosaics and Reptile Conservation in a Fire-Prone Region” Conservation Biology 27 (12)

Pastro, Louise L., Christopher R. Dickman and Mike Letnic (2011) “Burning for biodiversity or burning biodiversity? Prescribed burn vs. wildfire impacts on plants, lizards and mammals”  Ecological Applications Vol. 21, No. 8, pp. 3

Robinson, Natasha, Leonard, Steven, Bennett, Andrew, Clarke, Michael (2016) “Are forest gullies refuges for birds when burnt? The value of topographical heterogeneity to avian diversity in a fire-prone landscape” Biological Conservation 200, pp.1-7

Sitters, Holly , Di Stefano, Julian, Christie, Fiona, Swan, Matthew, York, Alan (2016) “Bird functional diversity decreases with time since disturbance” Ecological Applications, 26(1), pp. 115–127

Smith, Annabel, C.Michael Bull, Don Driscoll (2013) “Successional specialization in a reptile community cautions against widespread planned burning and complete fire suppression”Journal of Applied Ecology 2013, 50, 1178–118

The silver river

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.

Hazy foggy view from deck

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.

Pixillated tinnie in distance

Fisherman in the mist

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

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.

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!

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.

In praise of sewage

“Cockle Creek? Ooo, I wouldn’t put in there” my sister’s mate, the local, said “They’ve been dumping heavy metals in that spot for years! And there’s the sewage farm up the river as well.  I’d steer well clear”.

I muttered to my sister as we walked away “What do you think? Are you worried about heavy metals and sewage?”

“Nah!  Let’s do it!”

Sunrise on Lake Macquarie

Sunrise on Lake Macquarie

The power of poo.  Over the last couple of years, I’ve been hearing a lot about it from my fabulous friend and colleague, Cath Simpson, at this very minute writing a documentary for Radio National full of plops and splashes.

Thanks to some bad experiences with cholera and typhoid, we modern city dwellers generally a bit iffy about human excrement. But the bacteria that dwell in and on us – our own personal ecosystems – seem to be quite critical to human health.   While I’m a huge fan of the toilet, poo is not all bad.  If you have a nasty case of Clostridium difficile, for instance – an infection that kills 30,000 Americans every year, often older people in hospitals who have had their bacterial ecosystems depopulated by antibiotics – a “faecal transplant” from a healthy donor is might well be your best chance of a cure.

If the much of Western world, with its convenient superphosphate fertiliser and cow-pat free central heating, has been a bit “ew” about excrement, one sub-culture has held the faith.  Bird watchers have never lost confidence in the value of ordure.

Cormorant diving crop for trim

Painterly pied cormorant fishing in Lake Macquarie

When Birdlife Australia asks “where’s your favourite birdwatching spot?”, do you choose an offshore island, fringed with white sand?  the lush splendour of the tropical rainforest?  Or choice number three, a sewage treatment plant? And you guessed it, the first comment is a ringing endorsement of the glories of the Alice Springs Sewage Ponds.

So I wasn’t really surprised at the new and exciting birdlife I saw up  Cockle Creek in amongst the drowned computer monitors, abandoned bridge footings and Impressionist riverscapes subtly enhanced by a discreet discarded tyre.

So many striated herons I got bored of taking photos.  White-cheeked honeyeaters.  Orioles.  Black faced cuckoo shrikes. White breasted woodswallows, showing off their 80s batwing styling.   Double-banded finches with their neat dress shirts, black ties and cummerbunds.

Why are sewage treatment plants so great for birds?  Well, wetlands are a particularly threatened habitat – a third of Victoria’s wetlands have been drained over the last two hundred years, for instance – and old-style sewage ponds offer alternative places for birds to feed and rest, especially during droughts.  With plenty of nutrients, the settling ponds of sewage treatment plants actually offer more invertebrate snacks than natural wetlands, and sustain a greater range birds. Christopher Murray’s research in Victoria has found that newer treatment plants – the dynamic sounding “activated sludge” facilities – that take up less expensive real estate than old-fashioned waste stabilisation ponds (and smell better) are less appealing from a waterbird’s point of view.

If the news on sewage plants is pretty good, I’m not so sure about the heavy metals. Cockle Creek really has been a dumping ground for cadmium and lead, among other things, from the smelter in Boolaroo, on and off for more than a century.  There’s black slag from the plant tucked away in all sorts of unexpected places around the lake shore and lead, zinc, mercury and cadmium lurk in the creek’s sediment, 70 centimetres deep.

The smelter closed down in the noughties and the site is still being “remediated” for housing.  Previous “abatement” strategies seemed to involve scraping off a few centimetres of topsoil and (after most of the local pre-schoolers were found to have worryingly high levels of lead in their blood) urging kids to  “Wash wipe and scrape – you’ll be right mate!”. In the 1980s and early 1990s, the streets closest to the “The Sulphide” were rented out on the strict condition that the household should have no children or pets.

There’s a giant Bunnings there already, though, amidst the rubble.  Perhaps the logic is that the visiting DIYers are heading home to put a mallet through an asbestos wall, so where’s the harm in throwing in a spot of bonus lead?

The local birds seem to be doing okay, though.  A pair of ospreys nest at the top of a Norfolk pine at Speers Point, where Cockle Creek flows into Lake Macquarie, and this last year they’ve had chicks.  Osprey are locavores and since they’re at the top of the food chain, anything toxic in the fish they eat ends up in their chicks.  Eventually.  It takes a while for our endlessly updated array of contaminants – from DDT to teflon, fire retardants and hypertension medications – to make it into the bloodstream of the baby raptors.

Osprey wings bent crop wide

Osprey with fish at Speers Point, Lake Macquarie

I’ll be back to Cockle Creek for sure, to see what the local sewage has in store for me.  Trying to tread lightly, and hoping not to feel too much lead and mercury squelching between my toes…

D in canoe at dawn small more waterReferences

Murray, C. G. & Hamilton, A. J. (2010). Perspectives on wastewater treatment wetlands and waterbird conservation. Journal of Applied Ecology, 47(5), 976–985. DOI: 10.1111/j.1365-2664.2010.01853.x

Murray, C. G., Loyn, R. H., Kasel, S., Hepworth, G., Stamation, K. & Hamilton, A. J. (2012). What can a database compiled over 22 years tell us about the use of different types of wetlands by waterfowl in south-eastern Australian summers? Emu: Austral Ornithology, 112(3), 209–217. DOI: 10.1071/MU11070

Murray, C. G., Kasel, S., Szantyr, E., Barratt, R. & Hamilton, A. J. (2013). Waterbird use of different treatment stages in waste-stabilisation pond systems. Emu: Austral Ornithology. DOI: 10.1071/MU12121

Murray, C. G. & Hamilton, A. J. (2012). Sewage ponds a refuge for wetland-deprived birds. ECOS, 175. http://www.ecosmagazine.com/?paper=EC12418

Nine herons hunting

Nine herons hunting… could it be the beginning of a carol for Christmas-in-July?  Not a bad sound track, perhaps, for a paddle on a wintry 25th down Mooney Mooney Creek.

There were (roundabout) eight cormorants, some of them cacking….

… three posing pelicans

… two eagles soaring

And a kingfisher in a mangrove tree (no photo, naturally).

But realistically, I could only get all the way through the twelve days of anti-Christmas by including the many invisible mud-loving animals that all those herons were stalking.  And I’m not quite sure if I have the alliterative and euphonious verbs to use for them.  Twelve isopods…. idling? Eleven worms a-wobbling? Ten crustaceans crawling?

Even if it can’t offer swans a-swimming or geese a-laying, Mooney Mooney does pretty well for both visible and invisible animals, considering how damn noisy it is.

I first started dreaming about paddling this creek as we swooped above it, across the lofty freeway bridge.  It’s a gorgeous structure, if you are partial to well-formed concrete: elegantly curved, arching vertiginously above the treetops of Brisbane Water National Park.  An endless stream of cars and semis cross the valley on the F1, the main route north from Sydney, on the tallest road bridge in Australia, the still water 75 metres below.

The Pacific Highway, looping its way down to its own modest crossing point, has plenty of traffic too: bikers switchbacking their way up the old road. This Saturday, I didn’t see a soul in three hours on the river, but for a mile or more I could hear the hiss of compression brakes and the revving of engines.

And yet, if I had to pick a place, of all the waterways I’ve paddled so far, to find and fail to take a picture of a kingfisher, this rowdy river is the one I’d choose.  The traffic noise seems to keep the humans at bay, but not the herons.  What’s going on with the wildlife around here?

There’s plenty of evidence that traffic noise bothers birds.  I particularly like a recent experiment where researchers planted speakers in a long line to create a phantom road.  That’s just what the freeway feels like from Mooney Mooney Creek – a road you can hear all over but mostly can’t quite see.  The phantom road, with its invisible traffic masking mating and alarm calls and the sound of approaching predators, cut numbers by a quarter, and drove two species away from the area entirely.

Some cope better than others.  High pitched songs are less likely to be blocked out by the roar of traffic, and so squeaky voiced birds are more likely to hang around in noisy places.  Species with a little vocal versatility often start to sing a bit higher, a little slower or in purer tones, just to be heard.

If you’re carnivorous, being able to hear the critters scuttling around in the bushes is a boon. Seeds and nectar are less likely to make a break for it, so background noise seems to be less of a big deal for the plant-eaters.  Also, birds that feed on the ground seem to mind the noise less – perhaps there’s more obstacles between them and the din.

Everyone agrees that in loud places, birds spend more time on the alert for predators – a high maintenance lifestyle.  That said, some nest-robbers are also put off by the rumble of traffic, so for some species, chicks hatching in noisy nests have a better chance of survival.  If you can handle the decibels, you may have a competitive advantage.

What does all this tell me about the plentiful birdlife of Mooney Mooney Creek?  Thinking about it, I saw high-pitched squeakers, mud-hugging stalkers and sharp-eyed hunters (see, I’m getting into the swing of this avian carol singing thing!)  I’m guessing striated herons don’t echolocate for crabs.  This white-faced pair were happy to ignore not just the distant thunder of trucks but the much more immediate annoyance of a nosy canoeist with a camera.

“The mud is like a Christmas tree”, my eight year old said, hearing the story of my low-tide adventures, “and the bird were excited to find all their presents”.

When the eating is this good, it seems, the soundtrack scarcely matters.

References

Francis, C.D. (2015) “Vocal traits and diet explain avian sensitivity to anthropogenic noise” Global Change Biology 21(5), 1809-1820

Francis, CD and Jesse R Barber (2013). A framework for understanding noise impacts on wildlife: an urgent conservation priority. Frontiers in Ecology and the Environment 11: 305–313. http://dx.doi.org/10.1890/120183

Francis, CD, Ortega, C and Cruz, A. (2009) “Noise Pollution changes avian communities and species interactions” (2009) Current Biology 19(16) pp.1415-19

Patricelli, Gail L. and Jessica L. Blickley (2006) “Avian communication in urban noise: causes and consequences of vocal adjustment” from The Auk 123(3): 639-49

Low tide at Gunyah Beach

“The sea or not the sea?”

That was the question churning through my brain, as I set out for my first solo kayak on the Hawkesbury proper.  Let’s be kind and say I’m not a risk taker (there’s a reason I’m fond of chickens).  And my canoe is properly vintage, made out of wafer-thin plywood back in the early 70s, and now held together by a rich tapestry of epoxy based products and amateurishly applied fibreglass.  Don’t get me wrong – it was the best $100 I ever spent on ebay but our Egg is no ocean-going liner.

But setting off on a sunny Saturday morning with a light off-shore wind and a slack tide, I thought my decrepit boat and I might just be able to brave a three kilometre paddle along the widest reaches of the Hawkesbury Estuary, from Brooklyn’s Parsley Bay to Gunyah Beach in Kuring-gai Chase national park.

About midway across the 700 metres at the mouth of Porto Bay, I realised the weird rise and fall of the boat was swell, a new and disturbing experience for me as a canoeist.  Well, it was either swell or the kayak was being regularly nudged sideways by bull sharks.  Either way, I was not happy.   It didn’t help that the choppy water was full of floating branches, torn down by  last week’s big winds.  If the sharks didn’t get me, I’d be turned into a giant vegetarian shishkebab by a surfing pine tree.  I was in the ocean, and it was scary.

Of course, the Hawkesbury “River” is, kinda, the sea – a flooded river valley that has its tidal limit a hundred kilometres or thereabouts from its mouth.  Whenever I think about this, I imagine how strange it must have been for the people living on the plains that once stretched out from the current coastline under what is now the surface of the sea, as the ocean crept slowly up, over ten thousand years, claiming the valleys carved out by the river, pushing people before it into the hills.  Now that’s really going into the unknown.

In the end, of course, I made my little paddle with no problems at all, apart from an annoying lack of photographic evidence that there was ever anything to fear.  Gunyah Beach (boat access only) even had its own lounge suite on which an unnerved canoeist might rest and recover.  I’m pretty sure the contractual obligation white-faced heron had just stood up after a cup of tea and a chocolate digestive as I arrived.

Stumbling through the mud around the beach-side lagoon, I found myself in a maelstrom of silvereyes and white cheeked honeyeaters.  I’ve come to realise binaural hearing is a real asset for bird watching.  With one dodgy cochlea I spent half my time whipping my head wildly from one side to the other to work out where the chirping was coming from.  In the end taking random pictures of the bushes seemed the best way to avoid permanent neck injury. I was disproportionately pleased with the few photos that worked out. There’s something particularly delightful about the most minor victories over timidity and incompetence, even if you can’t convincingly frame pootling around in boats in your estuarine backyard as some kind of heroic feminist re-enactment of The Old Man and the Sea.