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.
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).
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?
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.
But if the male bird was playing favours, this was strictly a chick fight.
At first it was a rap battle.
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.
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).
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.
Is that a blood stained beak? Was this a ghoulish outcome of a predator attack followed by a desperate battle for genetic survival?
Or is it just mulberry season?
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