Wildlife reboot: birds 2.0

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

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

A “green” satin bowerbird panting in the heat

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

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

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

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

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

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

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

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

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

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

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

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

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

 

Previous posts about Ganguddy

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

Snakes versus whining teenagers – last year at Ganguddy

 

More on our sparrowhawk summer

Death and sibling rivalry

The new generation of sparrowhawks emerges from the nest…

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

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

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

 

Further reading

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

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

Battle of the baby birds

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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