Have you ever ventured into an open-wooded forest in the Northern Rivers at twilight?
If so, you may have been rewarded by a rare glimpse of one of our least-seen and most poorly understood birds – the Australian owlet-nightjar.
At just 25cm in length, this elusive, secretive creature has mastered the arts of stealth and camouflage.
It’s the smallest nocturnal bird in Australia and can literally hide in plain sight.
Nevertheless, towards the end of the 18th century, we know that at least one Australian owlet-nightjar was seen, because it was caught and dispatched from Port Phillip Bay to England.
Aegotheles cristatus
In 1790, naturalist George Shaw, a founder of the Linnaean Society and fellow of the Royal Society, christened this little bird with the scientific misnomer of Aegotheles cristatus.
This fancy name loosely translates as ‘crested goatsucker’, as Shaw and his contemporaries, understandably, believed the bird to be a type of nightjar.
And nightjars were long thought to suckle from goats – but that’s a story for another day.
Commonly called a fairy or moth owl, the tricky Australian owlet-nightjar, while sharing some similarities with owls and nightjars, is neither.
Its closest relative is the tawny frogmouth.
Fossil records show frogmouths dating back to the Quaternary Period in Australia – less than 1.85 million years ago, while a preserved owlet-nightjar fossil, discovered in the Chalk Mountain Formation of the Warrumbungles, was dated back 15 million years to the Neogene Period.
Binocular vision
Like owls, owlet-nightjars have large, forward-facing eyes in a facial disc.
Those big eyes improve eyesight, while eyes in front afford binocular vision, giving the birds depth of perception and the ability to judge distances more accurately.
These adaptations enhance navigation and hunting in the dark.
To compensate for their comparatively restricted eye mobility, owls and owlet-nightjars can rotate their heads through a wide arc.
The purpose of the facial disc – which is easier to discern in owls than owlet-nightjars – is to collect soundwaves and direct them towards the ear openings, located just behind the eyes.
This enables the detection and location of even the slightest movement of prey.
For the Australian owlet-nightjar, those prey items include insects and small invertebrates – think beetles, ants, spiders, mosquitoes, cockroaches, grasshoppers and flies, and it becomes apparent how vital a role the Australian owlet-nightjar plays in maintaining balanced ecosystems.
Well camouflaged
With plumage colours and patterns perfectly designed for camouflage, owlet-nightjars remain undetected as they perch motionless and patiently on a tree branch, waiting to pounce on unsuspecting prey.
Another hunting technique is the energy-conserving perch-and-sally, whereby the bird leaves its perch, catches an insect in flight and returns to the perch to consume it.
For the prey, there is no advanced warning as the moth owl is a silent flyer.
This adaptation is achieved by feathers with a fringed leading edge and a soft, velvety upper surface – traits that help reduce air turbulence, dampen sound and eliminate the flapping and whooshing noises commonly associated with birds in flight.
Found only in Australasia
Found only in Australasia, there are nine or perhaps ten owlet-nightjar species, depending on whether or not the New Caledonian owlet-nightjar still exists.
Luckily for us, the vocalisations of the Australian owlet-nightjars are best known.
Their calls are heard mostly just after dusk and before dawn.
They have been variously described as soft churrs, a grating churr, a ‘tew’, ‘che-ok’, ‘yuk’ or ‘tyeow’.
It may be a rising series of two, three, four or five notes, a sharp call or a hissy one.
Australian owlet-nightjars are cavity nesters.
Once upon a time, the cavity would have been a tree hollow and these remain the preference.
Unfortunately, with the clearing of woodlands, length of time it takes for a tree hollow to form, and competition from invasive species such as the common myna, cavity nesting birds have had to settle for alternatives.
Nest box dwellers
Fortunate ones might find themselves a comfy nest box.
David Brook from Wildbnb Wildlife Habitat says he has seen Australian owlet-nightjars at most of their project sites across the Northern Rivers – including in forest, agricultural and urban areas.
‘These birds are mesmerising’, says David, ‘and often stare intensely right at you from the hollow entrance’.
‘They’ve been observed roosting and nesting in a range of hollow sizes and designs, including the huge hollows (400mm wide x 1200mm deep) installed for glossy black cockatoos.’
Mate for life
Owlet-nightjars mate for life, setting up a territory that, for the most part, they occupy year-round.
They nest from July to December, laying between two and five white, oval-shaped eggs in a cavity lined with green leaves.
Both parents contribute to nest building, incubation of the eggs and caring for the chicks.
Happily, and in spite of falling victim to such predators as snakes, goannas, cats, foxes and dingoes, the Australian owlet-nightjar is spread far and wide across our continent.
It is categorised by the International Union for the Conservation of Nature as ‘Least Concern’.
So… if you go down to the woods tonight, you may be in for a big surprise.
With eyes peeled, ears tuned and mind on the job, you just might join the ranks of the privileged few who have seen or heard the bewitching Australian owlet-nightjar.
For more info, visit www.byronbirdbuddies.com.au.
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