Into the matrix

Gerogone profile distance for crop wide

A busy day at the bullrushes by Terry’s Creek for this brown gerygone.  It really got into  a frenzy as it threw itself around trying to tug away the requisite materials for nestbuilding.

Although they’re quite common up and down the east coast from far north Queensland, down to Victoria, where they’re actually expanding their range, this is the only place I’ve seen gerygones.  Half-way through my daily commute along busy Epping Road in suburban Sydney, in line of scrubby woodland only a couple of hundred metres wide flanking a malodorous creek  in a valley awash with weeds.  But there’s plenty of cover, a water source, and the bushland stretches maybe three kilometres along the creek, all the way down to Lane Cove National Park.

Gerygones are the kind of little insectivorous bird that do okay in quite small patches of suburban reserve, but absolutely don’t make the leap, in the words of Patricia Hodgson and Richard Major “into the matrix”.  The urban matrix, that is.  Some of the other birds I see regularly at Terry’s Creek – the white browed scrubwren and the red-browed finch – are quite happy hanging out in the scungy waste ground next to railway lines or dank weedy gullies, but are less keen on suburbia.

For some reason, silver-eyes are an exception – they’ve taken the blue and the red pill.  You find them both in and out of the urban matrix in “almost any woodland habitat“.  This one and his gang blithely flew in to have a nibble on a riverside pittosporum as I stomped around only an armslength away.

Silver eye and flower squarer

Silvereye in pittosporum

Some of the other locals at Terry’s Creek do sometimes visit gardens and backyards, but not ours (sniff).  I’m pretty sure our “house birds”, the resident red and little wattlebirds, keep them away. This week I’ve seen the little wattlebirds have a go at putting the frighteners on some much heftier residents.

Satin bowerbird at drink with wattlebird good crop

Head to head between a male satin bowerbird and a little wattlebird

Satin bowerbird scaring off little wattlebird crop larger.jpg

And it’s on!

Kooka and wattlebird 2 crop and amend

Just before the wattlebird bit the kookaburra on the bum!

And we’ve worked out why the wattlebirds are so aggro this weather.  Only a couple of metres from our backdoor, at eye level, right beside the path to the chook run and the washing-line, there’s a nest in the middle of one of our banana trees.

If you made an extensive search around the yard to try to find a place more exposed to human influence you’d be hard pressed to find one.  Tobacco fumes constantly waft around the nest from the chain-smoker on the back verandah, and children run past shouting maybe ten times a day.  More often, now we’ve spotted the nest and the two brown speckled eggs inside it.

The incubating female has a genuinely terrible approach to camouflage.  Whenever human is nearby, popping into the laundry or watering the herb garden, she points her beak to the sky and stays very still.  She’s pretending to be a stick, I think.  A surprisingly bird shaped stick with a beady, watchful eye.

Wattlebird on nest in banana tree mid

Female wattlebird incubating eggs in our banana tree

Wattlebird tail and banana crop

The tail’s a bit of a give-away as well.

Initially I figured that the wattlebirds picked this impropitious spot to raise their young because they were, frankly, a bit dim.  But then I thought back to last year’s summer of the sparrowhawks – the sheer number of chicks I saw eviscerated and the dramatic drop in local wattlebirds population at that time.

Now, the collared sparrowhawks seem pretty laid back about humans, spending more energy guarding their nest from raids by currawongs and channel-billed cuckoos than worrying about our comings and goings. But even so, I’ve never seen them perching on the back step or checking out the laundry.  So maybe the wattlebirds aren’t so stupid. Perhaps they’ve figured its safer to raise your young around the slow-moving noisy bipedal predators than the airborne ambush-hunting ones.  They’re not just surviving in the matrix – they know how to hide there.

Sparrowhawk light on beak crop

Collared sparrowhawk on the look-out for prey

References

Woods, K.A. 1996 “Bird assemblages in a small public reserve and adjacent residential area at Wollongong, New South Wales” Wildlife Research 23 605-20

Hodgson, Patricia, French, Kristine and Major, Richard E. 2007 “Avian movement across abrupt ecological edges: differential responses to housing density in an urban matrix” Landscape and Urban Planning Vol 79 Issues 3-4, pp.266-272

 

A ghostly tide in Calabash Creek

It’s true what they say: you can’t step into the same river twice.  Especially if that river is really an estuary, briny water moving up and down between the mangroves.

Last time I was in Calabash Bay, back in February, it was full of stingrays.  The bigger rays were over a metre from head to tail, the smallest a quarter of that size, sliding along the silty creek bed bottom at a surprising speed as I wrestled with the manual focus on my camera.

Sparkly trees distant amended fixed

Upper reaches of Calabash Creek

But this Sunday, in the golden hour, I floated alongside a parade of hundreds of thousands of jellyfish.  Not the jelly blubbers that gather in the bends and eddies of the Hawkesbury proper, orange and beefy and disturbingly solid under the paddle.  These were moon jellies, aurelia aurata, diaphanous as mermaids’ undergarments, their shadows on the sandy bottom more substantial than themselves, tumbling and drifting downstream.

Moon jelly with sparkly tentacles crop

Stinging tentacles on display?

They’re common enough, moon jellies.  They’re easy to see and easy to study because they like to hang out where we humans do.  Harbours and jetties give them somewhere to latch onto in the polyp phase of their intriguing two part life cycle. And blooms of millions of the medusa form – like the one I saw this weekend – are not unusual either, especially in enclosed and not too salty waters, where the nutrient level is high, the oxygen level low and predators are few.  But I’d never seen so many moon jellies in one place before, and never seen them here.  Perhaps the stiff south easterly breeze and a rising tide blew them implausibly high into the tree-lined reaches of Calabash Creek.

Smoky sunset with sparkles crop

Burns creek during a burnoff

Maybe it was a coincidence, but along with the mysterious tide of jellyfish, Calabash Creek and the trees and rocks that flanked it were draped with garish green algae.  The creekbed and mangrove roots were coated in it and dried mats of it hung like fragments of  ripped clothing from low branches.  Water quality is much better in the Hawkesbury these days, but it seems like Calabash Bay is a hotspot for algal blooms, both toxic and less so, thanks to sewage outfalls upstream and a legacy of nutrients from earlier, dirtier days buried in the sediment.

Whatever the cause, the creepy drapery and the feeling of being entirely surrounded by slowly moving, half-invisible jellies lent an otherworldly feel to these quiet waters.

So I guess I can’t say for sure whether you get to step in the same river twice.  My feet never went near that water.  They were tucked up in the canoe with no chance of touching ghostly jellies, stinging tentacles or strangling slime.

Burnoff smoke from berilee at sunset

Burnoff sunset over Berowra Creek

Blue eyes and biteys

Brown cuckoo dove eye

The glamorous eye of the brown cuckoo-dove

We’ve had a visit from some old friends this week: a gorgeous pair of brown cuckoo-doves. who each took a constitutional around our patio before reconvening for an exhaustive mutual preening session above the chicken run.  They’re rainforest birds, but don’t mind wandering away from damp gullies in search of tucker – fruit, mostly, along with seeds and the occasional flower blossom.  You’ll often find them in disturbed areas and roadsides, feeding off weeds like lantana and wild tobacco, so what with the great swathes being carved, legally and illegally, through East Coast bushland, they’re doing better than many other forest loving critters these days.

And they are expanding their range as well.  Back in the day, Sydney was the southernmost point you’d reliably find a cuckoo-dove.  No longer.  Just a continuation, I guess, of the species’ earlier journeys from the north, where several close relatives still live. In fact, the amboyna cuckoo-dove of Indonesia  and the Sultan’s cuckoo-dove of Sulawesi were considered part of the same species only a couple of years ago when I last wrote about these portly visitors.

Cuckoo dove looking back from water crop

Brown cuckoo-dove quenching its thirst in our bird bath

I’m not sure what attracted them to our place, now we’ve executed the humungous broad leafed privet that used to lure them here.  The fruit-bearing natives we’ve planted to replace this nasty weed – lillypillies, blueberry ash, koda, bolwarra, native gardenia, small leafed tamarind, brush muttonwood – are all too teeny to offer snacks of any significance.  I spotted the cuckoo-doves innocently drinking from the bird bath but I suspect they may also be implicated in the overnight disappearance of the fruit from our mulberry tree.  Though since I chose to plant the mulberry right next to our washing line, maybe that’s a good thing.

Cuckoo dove long tail amend

For me, cuckoo doves are all about those beautiful blue eyes, though their exceedingly long tails are also a feature, helping them with fruit nibbling acrobatics, and at one time  earning them the name pheasant-tailed pigeon.  But as far as science is concerned, they’re mainly interesting for their body lice.

Cuckoo pair grooming 2 amended cropped

A female brown cuckoo-dove being groomed by its mate

Normally, it seems, parasites co-evolve with their hosts.  A family of lice tend to be found only on one family of birds (and in fact, each species of lice normally exclusively hang out with one species of bird).  But the Ischnocera – the family of louse that this pair are trying to remove from each other, in a rather romantic manner – can be found on all manner of birds – not just pigeons and doves, but also pheasants, quails, partridges and indeed megapodes.  Though not apparently our local megapode, the brush turkeys, or “the bloody bloody brush turkeys” as they are usually referred to in our household.

But if cuckoo-doves brought their own personal payload of body lice with them when they moved south to Australia, they also do a fine job of cleaning up some other pesky insects –  fruit flies.  Along with ripe fruits, cuckoo-doves gobble up loads and loads of larvae.  One researcher went so far as to say that vertebrates like brown cuckoo doves are the “natural enemies of fruit flies” (Drew, 1987, 287), words to bring joy into the heart of a sub-tropical gardener.  But further reading crushes these dreams.  Yes, cuckoo-doves, (along with rats) made a huge dent in the fruit fly population.  But unfortunately, they did so in the course of eating most of the available fruit.

I guess, then, its lucky I’m hooked on the looks of our frugivorous visitors, and I’m not banking on them for pest control.

Gorgeous eye closeup for amend

The blue eyes of the brown cuckoo-dove

Additional references

Drew, A. J. I. (1987) “Reduction in Fruit Fly (Tephritidae : Dacinae) Populations in their Endemic Rainforest Habitat by Frugivorous Vertebrates” Australian Journal of Zoology 35 283-8

Gibbs, David (2001) Pigeons and Doves: a guide to the pigeons and doves of the world, Bloomsbury Books

Gosper, Carl and Gosper, Dennis (2008) “Foods of Pigeons and Doves in Fragmented Landscapes of Subtropical Eastern Australia” Australian Field Ornithology, 25, 76–86

Johnson, Kevin, Weckstein, Jason, Meyer, Mathys (2011) “There and back again: switching between host orders by avian body lice (Ischnocera: Goniodidae)” Biological Journal of the Linnean Society, 2011, 102, 614–625