Fly in, fly out

The first asparagus is up.  The greenflies are sucking the life out of the few broad beans plants that survived the gnashers of the garden’s winter visitors.  The bowerbirds are brutalising the new growth on the liquidambar, in a jaunty colourised style that makes me think we have a flock of Calamity Janes in the canopy.  Spring is here!

But what about the spring birds?  I haven’t heard the first koel of the season, but the channel billed cuckoos have squawked their way into our dreams.  And in the last week, a new rolling trill in the trees: the olive backed orioles have returned.  We rarely see them around here, but according to Michael Moorcroft’s “Birds of Australia” as “common”.  The emergent twitcher in me sighs.

I met a charming French skin specialist once, and asked her why she moved to Sydney.  “We have melanoma in France of course” she said “But really, if you are interested in skin cancer, Australia is the place to be”.

On the other hand, if you long for the sight of that first feathered visitor arriving from a epic transcontinental journey, you’re better off in the Northern hemisphere.  All the ocean in the southern half of the globe, moderating seasonal temperatures; barriers of forest and ocean; a less icy past; uncertain rainfall and an often arid climate; and (somewhat unconvincingly) weirdly, lots of  “V” shaped continents; all reasons I’ve come across to explain why we have so few migrating birds around here (Someille et al 2013; Dingle 2008).

Back home, two thirds of my French oncologist’s local birdlife would be part time residents.  But in Sydney, it’s maybe one in five.  In the outback there are nomads, roaming around trying to find things to eat in an arid landscape, but there are hardly any regular migrants at all.

silver-eye-chestnut-4-crop-larger

Tasmanian silvereye mid-migration, Zosterops lateralis lateralis

What we do have lots of in Australia are “partial migrants”.  Somewhere between a third and a half of bird species have some sedentary individuals while others take off in the colder weather (Chan, 2001).  Most silvereyes, for instance, stay put, but many Tassie birds – chunky numbers with chestnut sides, like the one above – fly across the Bass Strait in winter, possibly island-hopping as they make their way to Victoria, NSW and Queensland.  On my way to work the other day, I was was befuddled by the strange appearance of a crew of migrants – on their way home, perhaps – milling around happily in the company a bunch of plain-brand silvereyes.

Hard working bird lovers have been tagging silvereyes for 30 years (Chan, 2001), so we know what these guys are up to.  But in general, partial migrants are tricky customers – figuring which of the identical birds you see are interstate visitor and which are locals is mostly pretty hard to do.

After reading a bit about research on bird internal navigation systems, I’m starting to think this kind of deviousness may be payback.

One set of experiments involved keeping captive birds and observing what corner of their cage they batter themselves against, driven by migration-restlessness or Zugunruhe (one of those cool German words for which there is no English equivalent).  Researchers messed with the heads of these captive birds, using mirrors to shift the apparent direction of the sun so they could see what new quadrant of their cage they try to escape through.  Other experiments placed caged birds inside a magnetic coil to warp their sense of direction – a research activity truly worth of evil genius from X-Men. Although I do find the thought of a bunch of 1940s songbirds flooding into a planetarium – another early experiment – quite charming (Burton 1992).

 

dawn-moon-best-tight-crop

If you do see a trans-continental migrant in Australia, it will probably be a shorebird.  About 35 beach loving species migrate here (Dingle, 2008).  On a paddle up Mooney Mooney Creek last weekend, I was really happy to see one of them: an eastern curlew, its absurdly long beak mucky after joyously feasting on the mud-flat crabs off Spectacle Island.  Flying from Siberia will take it out of you. Between the bloody photographers, the houseboats and the jet skiiers, it’s not hard to see why these guys are classed as critically endangered around here.

 

 

References

Burton, Robert (1992) Bird Migration, London: Aurum Press

Chan, Ken (2001) “Partial migration in Australian landbirds: a review” Emu, 2001, 101, 281–292

Dingle, Hugh (2008) “Bird migration in the southern hemisphere:
a review comparing continents” Emu  (108), 341-59

Somveille M, Manica A, Butchart SHM, Rodrigues ASL (2013) Mapping Global Diversity Patterns for Migratory Birds. PLoS ONE 8(8): e70907. doi:10.1371/
journal.pone.0070907

R2D2 in black and white

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Additional references

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

Kaplan, Gisela (2015) Bird Minds, CSIRO Publishing

 

A flash of gold and a stash of blue

yellow boat and low cloud horizontal larger

Season of mists and mellow tinnies: the Hawkesbury in fall

Autumn lasted for aroundabout a fortnight this year.  The endless summer of an apocalyptic El Nino wrapped up in mid-May, giving the deciduous trees an extremely tight schedule to dispense with their leaves before this weekend’s torrential rain.

We’ve had autumnal glory in the kitchen as well.  When Keats talked about the “season of mists and mellow fruitfulness”, I’m not sure he was thinking about bananas.  In theory our crop of tiny fragrant fruits should have been perfect for lunchboxes, but I made the mistake of describing the first-ripened one as “Geoffrey”.   After this, not only Geoffrey but all his brothers were deemed “too cute” to be eaten.

As well as the gold in the fruitbowl, there’s been plenty of gold in the trees.  The yellow-tailed black cockatoos are back in force, mewling and crunching in the radiata pines.

Yellow tail and autumn leaves horizontal

Fly by from a yellow tailed black cockatoo

And for the first time this year, I’ve noticed the migrating yellow-faced honeyeaters.  Thousands of them pass through the Blue Mountains most autumns, it seems, but this year they’ve been funnelled between the mountains and the coast, through the Hunter Valley.  I first spotted them darting through the riverside casuarinas at Karuah National Park, on our trip north, but since we’ve been back, I’ve seen flocks of them with their travelling companions, the noisy friarbirds, pouring up the Hawkesbury.  I’ve even seen them on the way to work, taking a moment out on their journey to watch the commuters boarding the morning train at Berowra Station.

But not all the autumnal excitement has been touched with gold.  Last weekend, halfway through detaining my broad beans (fencing, netting and a mulch of lavender and liquidambar – doubtless all in vain) I spotted a little collation of royal blue underneath the pomegranate tree. Nerf gun ammunition, the lid of a milk container, a peg.  Signs that we need to tidy up the yard, and a hint that randy bowerbirds might just do it for us.

 

More autumnal reflections from our backyard:

Let them eat light!

Autumn in terminal decline?

yellow sunset medium.jpg

Backyard gold

Gymnastic bees, virgin fruit and the birds that ate spring

It’s the vernal equinox and out in the garden, the spring flowers are blooming.

It pleases me no end me to think that these little figlets are made up of hundreds of the most secretive of flowers, snuggled inside a hollow-ended stem.

As you can imagine, pollinating figs is an extreme sport.  It’s undertaken by the fig-wasp, which spends much of its 48 hours of life on a suicide mission for fig fertility.  The male wasps hatch, blind and wingless, gnaw their way to one of the as-yet-unborn females, mate with them (eww), chew them an escape tunnel (still not redeeming yourselves, guys) and then die without ever having experienced life outside their flowery prison.  The females emerge and flee, spreading pollen as they go, only to find and squeeze into a second syncope (the fig “fruit” to you and me) through a hole so tiny she rips her wings off in the process.  If she’s lucky she gets to lay her fertilised eggs amongst the miniscule flowers inside and promptly, you guessed it, dies.

It’s really quite a disturbing life-cycle.  It’s with some relief that I can say that my three fig trees – a White Adriatic, a White Genoa and a Brown Turkey – are, like most cultivated figs, sterile mutants.  That sounds bad, but it’s a walk in the park compared to the Gothic splatterfest of the caprifig’s lifecycle.

Figs are one of the very first plants to be cultivated by humans: they have been propagated by us since the Neolithic era, over eleven thousand years ago.  And the outcome of our long association with ficus carica is virgin birth.  Yep, that’s the meaning of parthenocarpy – the way that common cultivated figs produce fruit from female flowers unsullied by any male influence. Since their fruits are sterile, they rely on us to do the hard work of allowing them to reproduce. Bloody skivers.

Actually, humans are quite fond of producing such feckless fruits.  Bananas are a good example.  They’re sterile, thanks to their three sets of chromosones – just like those fast growing “triploid” Pacific Oysters I wrote about in my last post, reproducing thanks to genetically identical “daughters” and “granddaughters” that spring from the plant’s base.  Fig wasps and caprifigs have co-evolved – maybe in some weird cultural way, modern humans with their taste for large, fast growing and seedless fruit and our virgin orchards have done the same.

One way or another, people, myself included, seem to get a perverse kind of pleasure in frustrating plants’ attempts to have babies.

My broccoli, encircled by landcress that deals death to invading insects and safe inside the kids’ superannuated, net-enshrouded trampoline frame – has done really well this year.  Now the weather is warming up, however, it’s taking a real effort to thwart the reproductive desires of my brassicas.  Those tasty flower buds really really want to go the full distance and burst into bloom and it’s taking a serious commitment to broccoli-eating to cut them off at the pass.

I tried, but it’s too late for that for the rocket, the mizuna and the tatsoi – these spring flowers are in bloom, like it or not.

I’m happier about these vernal blooms: magnificently monochrome broad beans in all their line-print glory.

I was a bit worried about my broadies this year, incarcerated as they are beneath the chook dome, my first line of defence against the brush turkeys.  Would the pollinators be able to make it through the 1 cm square lattice of the dome’s aviary wire?  As I noodled around in the garden the other day I had my answer. A European bee hovered indecisively, making careful mental calculations or perhaps looking for a door handle.  Eventually, it seem to sigh and alighted briefly on a wire, adopting what can only be described as a pike position and plunging through for a perfect 10 entry.

It’s a bit early to say, but I think I can see a few tiny bean pods forming so I’m hoping that while I’ve been otherwise occupied we’ve been visited by other elite insect athletes up for the gymnastic challenge.

The local birds seem to be almost as ambivalent about the signs of spring as I am about my brassicas going to seed. The bowerbirds are doing their valiant best to rip all the buds off the liquidambar and the little wattlebirds have been paying excessive attention to the flowers on the chinese lantern.  They’re either defending them from insect attack or eating them – I’m not quite sure which.

I don’t think these red wattlebirds would be capable of doing any damage to the heavy duty flower of a gymea lily, even mob handed.  These monster blossoms are bird pollinated – the red colour scheme is a dead giveaway apparently.  I guess this is the honey eater equivalent of an all-you-can-eat buffet.  Since you can roast and eat the roots and the young flower spikes it could even be supersized bush tucker for us humans too.

Enjoy the equinox: may all your spring flowers be excellent eating!

Some like it hot

After months of tattered leaves and mysterious disappearing fruits, I’ve finally got a small but perfectly formed crop of jalapeno peppers.  Christmas in Anglo Australia traditionally involves pacing around a baking kitchen with novelty oven gloves and lingering anxiety about possible food poisoning, so pickling something hot would seem seasonally appropriate.

I’ve figured out why I have anything to preserve.  Sometime over the last week or two, the robotic clicks and chirrs of the satin bowerbirds have faded out of our soundscape.  I’m not sure where our place fits into satin bowerbird’s cycle of the year.  Does our backyard counts as “open woodland” where according to WIRES bowerbirds move in autumn and winter? Or is our vegetable patch a “territory… occup[ied] year after year” in the spring breeding season….?

One way or another, having kept the overshadowing trees in trim all winter, (with the odd mouthful of chilli leaf, grape vine and mulberries, just to freshen the palate) it seems they’re off to do their fine topiary work elsewhere.  I just hope the spiky sticks that I used to fence in my chilli plants in a vain attempt to protect them from marauders didn’t do any permanent damage to their lovely violet eyes – I’m pretty sure topiary, not to mention collecting and arranging blue pegs, is easier with binocular vision… But do satin bowerbirds have binocular vision…?  That’s a research project for another day…

Blood on the mulberries

This means war!  Or at least a humanitarian mission with military elements.

Just when you’ve been lulled into a false sense of security by their generous assistance with your passive solar, suddenly the bowerbirds turn against you.   One minute they’re giving the liquidambar a light trim, the next they’ve descended on your mulberry tree and stripped it bare.

Mulberries are perfect backyard trees.  They’re easy to grow, fruit without chilly weather, and produce berries in spring before the fruitfly really get into gear.  Kids love to eat them: the Halloween themed blood-stained hands afterwards are a bonus.  You can feed them to silkworms which sorts out any number of school projects (and if you’re that kind of person you can weave your own scarves or caftans).  Chooks happily clean up the spoil.  And you never ever see mulberries in the shops – when they’re ripe they’re so soft and juicy they’re unshippable.  You have to eat them warm, straight off the tree.

And if that’s not enough, they also make a great spot for a diamond python’s mid-morning nap.

mulberry bush and snakey

There’s not much you can do wrong with mulberries, or so they say.  You’ve gotta love trees about which it can honestly be said: “you cannot kill them”.  You have to prune them for new growth and berries, but hacking randomly does seem to more or less work, though the outcome might be described less as “a classic open-centred vase shape” and more as “an ugly mess”.

The only bit of advice that people regularly give about mulberry trees is to avoid planting them near paths “to avoid stains”.  Given the chaotic state of our garden, I smiled smugly at this.  And then planted mine right next to the washing line.  Oops.

I know, I know, my Hick’s Fancy should have been netted against the birds (given that they can be weedy, this is probably a good idea for ecological as well as harvest-maximising reasons).  But the bowerbirds haven’t stopped at the mulberry.  They’ve also had a good go at the grapes up the granny flat wall and the kiwifruit vines on the “solar pergola”.  Exclusion netting is all very well but short of getting a great big net dropped from a helicopter to drape over the whole house and yard, there’s only so much you can do.  Thinking about it, that actually sounds like a lot of fun.  All I need is some air support.

Bowerbirds: snacking for solar gain

Before the fall

Before the fall: it’s always sunnier on the other side of the fence

The gang’s back.  Loads of satin bowerbirds in the garden at the moment.  I’ve seen a couple of mature males, with their glossy blue-black feathers and gorgeous indigo eyes, but most of the robotic whistles, clicks, churrs and cracks in the trees seem to be the “greens” – juvenile males and females, hanging out in a pack.

I’ve heard grim stories about the antics of bowerbirds in the veggie garden.  Apparently they like to lull the backyard grower into a false sense of security and then swoop in and devastate your greens.  But I’m feeling kind of relaxed on that front.  After the brush turkeys exhumed my long awaited Hass avocado treelet, and my big girls, the young-bloods, the prodigious egg-layers, started lounging around under the baby banana trees, making eyes at my kale and chomping on every “poisonous” rhubarb leaf the moment it unfurled, I’ve decided to go totally Christo.  Every seed, every seedling, every newly planted tuber has its own little  blanket of horticultural fleece.  Anything growing that’s remotely likely to appeal to the poultry palate is swathed in netting.

The one upside of the chooks’ blithe disregard of the garden fence is the complete and total elimination of trad from the veggie patch.  Three months ago our spindly raspberry canes and brave little Nightingale persimmon were drowning in a lush wash of juicy stems and emerald leaves, even as the ground slowly dehydrated around them. But now – nada.  A few stems scattered around, waiting to reroot after the rain but not a leaf to be seen.  It’s all very satisfying.

So it’s not all bad when your flock take to the greenery.  The bowerbirds haven’t got a chance of getting my broadbeans.  But with their leaf-picking ways, they are doing sterling work for the environment.

Brushturkey in liquidambar

Brush turkey roosting in our poor denuded liquidambar

Their latest hang-out is the neighbour’s liquidambar tree – gorgeous and looming, throwing a great long shadow across our ice-box house all autumn. Basking in the sunshine on the other side of the fence, it steadfastly refuses to shed its leaves, months and months after our poor overhung specimen has shivered and shaken off its own.  And then, when the last ruby shreds are about to be blown from its branches, and the winter sun finally promises to warm our August days, the bloody thing starts growing leaves again!

But never fear, Super Satin Bowerbird is here!  I can’t prove definitively that their main objective was improving our passive solar gain but after closely studying these photographs for insights into bowerbird psychology and culinary habits, it certainly looks like it.