Sparrowhawk summer

The sparrowhawks in the bottom of the neighbour’s yard have beaten the odds.  Despite the visits of the hungry currawongs and randy cuckoos, two strapping fledglings have emerged from the nest this week.

Two juvenile sparrowhawks trying out their wings

Our days are punctuated by the insistent call of the mother and father hawks telling the teenagers that it’s time to head back to the ridiculously tiny nest for dinner.  And the juvenile’s answering pitiful cries, disproportionate to their galumphing size.  They’re easily as big as their parents even at this early stage.

Photo of juvenile sparrowhawk with its mouth open

Fledgling sparrowhawk talking back to its parent

And early in the morning, the ding-dong battles between the sparrowhawks and the local mob of sulphur crested cockatoos, that wheel across the valley each day to find the tastiest trees and finest roosting places. The hawks have been watchful but apparently unconcerned by the range of large and small humans arguing, gardening, driving, swimming and playing beneath their nest and, as you can see, endlessly photographing their activities.

But the arrival of a crew of a dozen or so seed eaters in their territory was apparently intolerable.  A crested pigeon is the biggest prey sparrowhawks have been known to take, but we’ve seen for ourselves they’re not afraid to send cockies and cuckoos packing.  The cockatoos didn’t take off without a bit of argy bargy but in the end the diminutive predators won the day.

The flock retreated off to our place, and relieved their frustration with some light demolition work on the rotting pine tree in our backyard.  I assumed it was the parents that did the chasing off, but Stephen Debus, who spent a lot of time hanging out in the Bundaberg Botanical Gardens with a digital camera and a pair of young sparrowhawks, seems to think that the young ones like to chase away bigger birds that they couldn’t possibly eat, everything from egrets, darters and ducks to kestrels and even currawongs, their erstwhile enemies.

There’s been an exciting new development in the last couple of days: the littlies are trying their hand with disembowelling.  Young nestlings are fed gobbets of freshly plucked bird flesh, straight from mum or dad’s beak, but this youngster was doing his own kitchen prep.  It took him a while.  Given the eye-claw coordination on display here, it may be a few weeks before this one is hunting on its own.  It seems that taking dinner from the talons of parents mid-air (and maybe snacking on cicadas in between meals) is the next step towards independence.

From the vantage point of our neighbours’ pool, we’ve watched the fledglings practicing their short haul flights (and awkward landings), whine a lot and bicker over food.  In a truly rare sighting, judging from my experience with human children, I even saw one of them give in to his sibling’s relentless complaining and share a meal.

Or maybe what I saw was big sister muscling in on little brother?  Sparrowhawks have distinct sexual dimorphism, and apparently any idiot can tell the smaller males from the females.  Not this idiot!  I look forward to being enlightened by sharp eyed readers.

As you can tell from the recent posts in this blog, I have got just a little obsessed by our in-house raptors these last few months.  Maybe because our four serial killers have cleared the area of other distraction – the usual “house” birds.

No baby brush turkeys this year (hooray!) and the noisy miners have been mercifully silent. But the gorgeous satin bowerbirds have also been thin on the ground, the newly arrived whipbird disappeared suddenly without leaving a forwarding address, and I’ve heard very few of the chocks and clucks of the wattlebirds that make up the usual soundscape of our neighbourhood.

We have about six weeks, it seems, before the young sparrowhawks will disperse, looking for another neck of the woods with the requisite tall trees for nesting and plenty of small gormless birds to ambush from a secret spot in the canopy.

Will the adults stay after the brood has gone?   Will they leave and come back next year?  It seems no one really knows much about the movement of these secretive birds, despite their presence all over Australia, in every habitat but the driest of deserts.

And, if our lovely raptors do leave us, will our usual cast of feathered friends – the nectar drinkers, the seed and flower and lerp eaters – return?

Further references

Barnes, C.P. and Debus, S. (2014) “Observations of the post-fledgling period of the collared sparrowhawk (Accipeter cirrocephalus)” from The Sunbird (2014) 44(1): 12–23

Debus, Stephen (2012) Birds of Prey of Australia: a field guide, CSIRO Publishing

 

More sparrowhawk stories from our backyard

The end of the brush turkey plague? The battle of the baby birds….

There’s a collared sparrowhawk nesting in our garden…. or is it a goshawk…?

and the latest from our backyard: the teenagers start hunting for themselves… Sibling rivalry amongst the young serial killers….

 

 

 

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