Category Archives: brood parasites

Standard

Posted by

Posted on

February 6, 2021

Posted under

Backyard birds, brood parasites, feeding fledglings, habitat, Insects, Native birds

Growing up is hard to swallow

Juvenile koel in a pitto tree

It’s all about the young koels in our yard at the moment.  We have at least two of them hanging around the back yard, begging for food and slowly destroying the mental health of their red wattlebird adoptive parents.  Well, I hope for their sake there are more than one set of parents doing the provisioning.

Red wattlebird with spider for its koel young
Red wattlebird ready to take off with its spider
Wattlebird feeding a koel chick
koel mantling for a discreet meal

While I’m still hearing koels begging endlessly, I have a suspicion that the parents are trying to  back off from supplying food. As a parent of teenagers I can certainly empathise.  Wattlebirds normally feed fledgelings for two or three weeks after leaving the nest.  The soundscape of our yard started to be dominated by the pleas of the koel youngsters around mid-January, so I think the parents’ patience is starting to wear pretty thin. I’m pretty sure that the koels are trying to push that envelope though.

I watched this rather grown-up looking chick sitting on a branch to beg relentlessly for at least half an hour without attention.  It whined and shuffled, whined and groomed.

Koel impatiently grooming

It seemed to despair of getting any attention at one point and started rummaging around for its own tucker.   Clearly this flaccid flower didn’t cut the mustard.

Desperation drives an attempt to eat whatever was within reach

Eventually the relentless moaning did result in a couple of snacks.

Koel fledgeling begging
Wattlebird coming in with food
A big mouth…
…being fed

While waiting …. and waiting, and waiting… (I was almost as impatient as the koel for this fledgeling to get a feed…) I spotted a second youngster lurking nearby.  It looked a bit skinnier and its plumage a bit patchier and at first I wondered if it was a younger chick, hogging the attention of the exhausted parents.  But usually female koels only lays a single egg in a nest – which make sense since the chick heaves competitor eggs and hatchlings out.  Sometimes, it seems, koel females will return to lay an egg in a sequence of different nests so perhaps this second youngster was being fed by a different harried parent.  I feel kind of relieved on their behalf.

Nestmate? Biological sibling?

One way or another, all that whining seems to be getting less of a response this weather.  So our backyard koel chicks are having to forage for their own food. This nugget looks kind of unappealing, though perhaps no worse than the spider that I saw mum or dad retrieving a couple of weeks ago.

Koel chick with mysterious food

Our neighbour’s bangalow palm seems to be a favourite foraging ground.

Koel in the bangalow palm.
Koel in bangalow palm

Perhaps the temptations of the palms are a bit too great.  Last week, I watched a youngster beg from a branch near our back verandah for a while.  No parental attention was forthcoming, and I thought it had given up, as it went surprisingly silent for quite some time, hunching and looking pensive.  Then this happened:

Juvenile koel waiting for…
this cameo appearance
from a bangalow palm fruit
and its subsequent disappearance

I think this mysterious fruit must have been stashed in the bird’s crop, .  Certainly this same koel was stacking away the berries at an extraordinary rate on its visit to the bangalow palm, so the idea that it was tucking it away for a later snack seems pretty plausible.  Having read a bit about the way birds use crops – a muscular pouch in the oesophagus that stores food – I am now tremendously jealous.  What a terrific idea!  Why the hell don’t humans have one?  I suppose blokes can use beards, although that’s a visually disturbing alternative.

Koels – noisy, whiny parasites – get a bit of a bad rap around here, but I can’t help admire them – their chutzpah, their gorgeous feathers, and their admirable capacity to never, it seems, go hungry.

Koel posing

 

Standard

Posted by

Posted on

December 21, 2016

Posted under

brood parasites, Native animals, Native birds, Pollination, Uncategorized

Comments

4 Comments

Poor lost souls

koel-mouth-open-cropped

There’s new sound in the garden just now.  A plaintive relentless cheeping.  But not the tiny piping tones of a naked, newly hatched chick.  No, it’s the muscular alto plea of the ginormous eastern koel chick to its diminutive red wattle bird parent.

And the wattlebirds are desperate.  I eyeballed the juvenile koel, lounging comfortably high in the canopy. Meanwhile its parent wheeled and fluttered in frenzied manner, perching here and pecking there, apparently driven to madness by the insatiable appetite of its parasitic offspring.

koel-and-mum-with-bent-neck-for-crop-amended-small

No sooner was the mega-chick fed than it returned to its incessant harping, as if unloved and cruelly abandoned.

koel-curved-neck-crop-real-crop

As I crashed around trying to get a clear shot of the elusive ear-splitting koel, I saw, at the top of the very same tree, something I’d never seen here before, something genuinely sad and alone.

flying-fox-illuminated-ears-cropped

A flying fox all by itself, a good twenty kilometres from the nearest bat camp way down the Pacific Highway at Gordon.

Flying foxes are very mobile, travelling up to 120 kilometres a night to feed.  We often hear them around our place on summer evenings, squealing and hurling fruit around.  During the year they migrate long distances following the peripatetic flowering seasons of eucalypts, melaleucas and rainforest trees, pollinating as they go.  Just like giant warm blooded bees, they carry pollen on their fur from one fragment of forest to another.  Flying foxes have been tracked moving as far as two thousand kilometres over the course of nine months and bat encampments have been described as more like railway stations or youth hostels than places of permanent residence.

But mega bats are sociable creatures and finding one on its own in the daytime like this is not a good sign.  I realised later I should have called the local WIRES group so someone with more expertise and a better head for heights than me could shin up its extremely tall tree to check it wasn’t injured by any of the usual suspects – barbed wire, open weave fruit netting or a dog bite.  But by the time I worked that out, it was the next morning, and the bat was gone – back to its digs in the local “Batpackers”, I hope.

I know some people feel about flying foxes the way I do about brush turkeys.  If you’re a fruit grower in NSW it is still possible to get a licence to shoot them to protect your orchards, although the mega bats actually prefer pollen and nectar as a food source – and  tightly secured, finely woven netting (one you can’t poke a finger through) protects crops better than a shotgun anyway.  In my backyard, the bats would be at the back of a very long queue for the ripe fruit anyway.  Ahead of me, of course, but behind the cockies and the possums for sure.

Deforestation means that there’s more conflict between flying foxes and humans these days, as the bats move into  the leafy suburbs where the fruiting and flowering plants are diverse and well watered.  They’re chatty critters with some “interesting” habits – urinating on themselves and then fanning their wings to cool down for one – which some people living nearby can find a hard to take (not to mention a couple of rare but deadly bat-borne diseases).

But the visibility of flying foxes in east coast Australian cities conceals the fact that (unlike brush turkeys) their numbers are in major decline.  One article suggests that at current rates, the grey headed flying fox, the type I found in my backyard, will be extinct by 2070.

The mega bats are particularly susceptible to high temperatures.  They start to “melt from the inside” in the words of a scientist, at just about the same temperature that is unsupportable for stingless bees, 43 degrees C.  A couple of years ago in Queensland,  45,000 megabats, mostly the tropical black flying fox, died in one day during a heat wave.  But high temperatures may just be the final straw when bats are short of food anyway.

Over the last couple of weeks, there have been scores of baby grey-headed bats found dead in parks along the east coast.  Both habitat loss and the aftermath of an El Nino, according to researcher Peggy Eby, have led to a food shortage.

“The mothers are going through a difficult nutritional phase, and they’re reducing the amount of milk they’re producing and the young starve.  They hang on to the females for the first several weeks of life, when she flies from the roost at night, and they simply would lose the strength that they need to hold on.”

I’m not sure why this stray found its way to our yard.  I hope it wasn’t injured here.  We don’t have a dog or barbed wire and we use veggie nets to keeps the bowerbirds and the brush turkeys off the fig trees (or if we’re feeling cheap, old trampoline netting from the side of the road).  But we still haven’t raised the cash to chop down the nasty cocos palm that is so appealing and yet so dangerous to flying foxes.

I hope the neighbours’ pool gave was a spot for a cooling bellydip and the jungle at the bottom of the yard gave it somewhere to recoup, recalibrate its GPS and get ready to head back to its pals at base camp.  Lovely as it was to have the chance to take his photo, I hope we hear him but don’t see him again.

Standard

Posted by

Posted on

November 2, 2016

Posted under

Animal communication, Backyard birds, brood parasites, Native birds, Uncategorized

Comments

3 Comments

Blood feud in the dawn redwood

male-koel-neck-arched-square

Every year for the last seven years, I’ve heard koels calling, loudly and desperately, right outside my window, day and night, for the three months from the equinox to Christmas.  And for the whole of that time I’ve been trying to get a decent photograph.  A while back, I caught sight of a whopping great juvenile sitting around on a branch of the pine tree, whining for more food from his adoptive mum, a harassed looking red wattlebird. But that’s it.

I know they’re there, skulking in the trees, the males advertising their availability in an increasingly high pitched, eventually hysterical squeak from the cover of the leaves.  And there’s that duet that koel couples, both equally well concealed and well amplified, produce – the male exclaiming “wurru-wurru!” while the female interrupts with a simultaneous “keek keek keek!”.  But where are these potentially ear damaging exchanges coming from?  Who can say.  It’s like trying to locate a pair of shy and slightly drunk ventriloquists.

But that all changed in my backyard yesterday.  I’ve finally got my stash of koel shots.

Why did these cryptic birds let me get close enough to take a million pictures?  I reckon it was because there was a battle on in the branches.   The prospect of scoring, through combat, a romantic enounter with the iridescent, satan-eyed male seem to make the feuding females oblivious to all that clicking and crashing in the undergrowth.

Curious male koel
Satanic looking male koel

The  sexual proclivities of koels are not well understood (by humans anyway.  You hope koels have a decent grip on it).  Brood parasites are inherently interesting critters, so koels’ interactions with the honeyeater “hosts”, whose nests they visit to lay their eggs, has been studied exhaustively. The changes in their migrating habits as the world warms up have been looked into a bit as well (eg Chambers et al 2014).  But how and with whom they do their coupling is all a bit of a mystery.

You can’t give the ornithologists too much grief about this.  Even the most avid twitcher is going to be a bit dubious about spending the three years of a PhD shinning up trees clinging to a GPS tracking device, in an attempt to pin down the sexual encounters of an intercontinental migrant of no fixed abode.  And that’s not even considering the koel’s antisocial habits: the fact that they are “typically wary and difficult to observe [remaining] in thick foliage, high in trees, calling from concealed positions” (Healy and Healey 2007).

female-koel-peeking-around-leaves-crop

So what did I see (or half see) in our metasequoia tree after breakfast yesterday?

Did I witness a female, already partnered however temporarily with Mr Shiny Feathers, being challenged by a youngblood for access to a mate?  Koel males are apparently “polygynous” – they mate with multiple females.  But those ventriloquist duets suggest some kind of short-term liaisons, since couples that sing together like this, apparently, often have some kind of ongoing arrangement (Maller and Jones, 2001).

Or just two females both keen to hook up with guy who had command of such a fine calling station, my beautiful dawn redwood?

Male and female koel closeby
Male koel in profile

 

The male was staying well out of it, watching cagily from the side lines.  At one point I spotted him passing something – a nuptial gift of a berry? – to one of the warring females.  I didn’t see if him get anything in return, unlike the lucky Asian koel spotted by this Singapore based bird watcher. But then with bird couplings, blink and you could easily miss it.

koel-eating-a-seed-crop-for-amend

Female koel… with nuptial gift?

 

But if the male bird was playing favours, this was strictly a chick fight.

At first it was a rap battle.

Female koel calling
Female koel calling

Eventually the two females settled at opposites ends of a branch, studiously ignoring each other, like gunfighters in a Western pacing the far ends of Main Street.  And then it was on, with a flurry of feathers and a fanning of tails.

two-koel-on-branch-flipped-and-cropped

Two female koels about to tussle

 

Female koel gearing up for action
Female koel looking pensive
Ruffled feathers after the encounter
Heading into the fight

Such chick fights aren’t as unusual as old-fashioned zoologists might think. Females that live in groups, it seems, often engage in “intense female-female competition over reproduction, dominance rank and other components of social-living” (Rubenstein, 2012, 2250). I’ve seen it with the chickens.  According to the implausibly named Clutton-Brock and Huchard, in a recent article for the Royal Society these fights “peak… during the reproductive season [81–83], and … can lead to wounding or death [28,84].”  And fights are not just about access to mates, but about protecting eggs or nesting sites, space or foraging territories (Tobias et al, 2012; Krieg 2016).

Intriguingly, competition between females seems to go along with good looks or “ornamentation”.  Or better still “ornamentation and weaponry”.  And female koels, while not obviously armed to the teeth, surely are beautiful birds; like most ornamental or colourful females both substantial in size and hailing from the tropics (Dale et al 2015).

sideish-female-koel-with-good-view-of-stain-include-square

Hang on, what is that mysterious red stain on that creamy chest?  Was this a battle involving “wounding or even death”?  Was I witnessing an injured female being challenged, in her moment of weakness, by a healthier rival?

In some of my photos it surely looks like it.

Female koel with unstained chest
Weary and stained looking female koel

Is that a blood stained beak?  Was this a ghoulish outcome of a predator attack followed by a desperate battle for genetic survival?

female-koel-with-red-beak-squareOr is it just mulberry season?

Quizzical look for a female koel
Quizzical look from a male koel

References

Chambers, L E, Beaumont LJ, Hudson IL (2014) “Continental scale analysis of bird migration timing: influences of climate and life history traits” International Journal of Biometeorology 58 (6) 1147-62

Dale, J., Dey, C, Delhey, K, Kempenaers, B, Valcu, M. (2015) “The effects of life history and sexual selection on male and female plumage coloration” Nature Vol 527 pp.367-71

Healy, C and Healey, E (2007) “Diet and Roost-site Fidelity in the Common Koel
Eudynamys scolopacea in Suburban Darwin” Australian Field Ornithology 2007, 24, 184–186

Maller, C J and Jones, D N (2001)”Vocal behaviour of the Common Koel, Eudynamys scolopacea, and implications for mating systems” Emu, 2001, 101, 105–112

Rubenstein, D.R. (2012) “Sexual and social competition: broadening perspectives by defining female roles”  Philosophical Transactions: Biological Sciences, Vol 367 No 1600, 2274-2293

Tobias, J. et al (2012) “The evolution of female ornaments and weaponry: social selection, sexual selection and ecological competition” Philosophical Transactions: Biological Sciences, Vol 367 No 1600, 2274-2293

Krieg, CA, Getty, T. (2016) “Not just for males: females use song against male and female rivls in a temperate zone songbird” Animal Behaviour Vol 113 39-47