Does Australia’s farting bird pass the sniff test?

Legend has it that skulking on Austalia’s forest floors is a bird which forages for earthworms by farting. The hapless worms are so startled by the sensory assault of a Bassian thrush’s fart that their dismayed writhing puts them in mortal danger. Following a quick toot, the gaseous bird simply plucks whichever vermiform vittles volunteer themselves from their humic harbour.

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The Bassian thrush (Zoothera lunulata) is a bird of gullies and damp forest floors. Its predominant distribution is south east Australia. Image by Leo (CC BY-NC-SA 2.0)

Today, for those who believe this marvel of natural history, the world becomes a little less magical.

Having incorrectly answered a trivia question on Bassian thrush farting, I was recently moved to fact-check this suspect nugget. My initial searches found nothing but a few webpages referring to one another, a book without citations, and nowhere could I find a reference to the primary source. A literature search also turned up nothing useful apart from a 2016 paper describing observations of Bassian thrush foraging ecology, yet there was no mention of the birds venting vapour.

Following a plea to Twitter’s sharpest bird and fart minds, the primary source was soon unearthed for all by Alex Berryman.

The original observation appeared in a 1983 paper published in South Australian Ornithologist. The reason I couldn’t find anything was that both the bird’s common name and scientific name have changed since the publication of that article.

So what is the evidence that has carried this remarkable phenomenon into Bassian thrush canon? The paper describes a behaviour of dipping the tail (“vent-dipping”), coincident with a noise “similar to a jet of air”. Probing of the soil surface for worms immediately follows. Between vent-dipping, the birds also “shiver”, and whilst shivering there is audible a “very soft sound somewhat similar to an inhalation gasp”. We aren’t told how many birds were observed doing this, and on how many occasions (the paper records 29 total observations of thrushes), so it is up to the reader to decide how common or deviant this behaviour is.

The speculative leap made from this unusual behaviour is that the fart is a strategy to induce the worms to suddenly convulse in repulsion, and reveal their location to the flatulent forager.

From Edington, JSL. 1983. White’s Thrush: Some aspects of its ecology and feeding behaviour. South Australian Ornithologist, 29, pp.57-59.

“The louder of the two noises described (that accompanied by a downward movement of the vent) may well be a ‘scare tactic’ to induce earthworms to contract reflexly (or other prey to move away) and so betray their presence to the Thrush through noise or litter movement and vibration. That these louder noises were made only during foraging, were antecedent to the probing and were more frequent with more intensive foraging, suggests that they were indeed somehow used to detect prey.”

Further, that shivering serves to reload the bird’s cloaca for another blast.

“If the source of the louder noise is assumed to be from the quick passage of air through the vent, then the softer, antecedent noises (each accompanied by a body shiver) might be explained as aerophagia – the gulping of air.”

Now this sphincter-percussion all sounds a bit bizarre, but is not without some scientific precedent. One expert to chime in on Twitter was Dr Dani Rabiotti, author of the book Does it Fart? The Definitive Guide to Animal Flatulence

Dani suggests this could be a case of ‘cloacal popping’, or simply a sick bird.

After scratching through the litter of evidence here, I feel it’s time to clear the air. There is simply no compelling evidence that the Bassian thrush uses farts to scare and catch worms. There are some curious but unquantified observations of a bird or birds at one site making some noises that could be due to aspiration and expulsion of air via the cloaca. There are no observations tying this to success in foraging. There have been no subsequent observations supporting the behaviour described in the original paper.

I’m afraid we, as lovers of truth and nature, must let the air out of this myth. Finally, we must all commit from now on, whenever we see a Bassian thrush, to carefully watch its arse, for science.

The Toadlet Diaries 2: Gulf country.

In 2010 I was fortunate to accompany herpetologist Dr. Renee Catullo on a trip through Australia’s Top End collecting little brown frogs. Here are some of my field notes along with photography. While my photography has vastly improved, I’m not sure I’ve felt so inspired to write since that trip. I hope this series of vignettes communicate some of the flavour and excitement of the wet season in Australia’s monsoon tropics.

(Part one here)

31 January 2010

I was relieving myself a stone’s throw from the inundated Carpentaria Highway when I saw my first Brolga. Its lanky form drifted indolently against a pastel sky as the tropical sun poured out late afternoon’s final slanting blaze. I finished my business, picked up my binoculars and shovel, tucked the bog roll under my arm, snatched a nearby burrowing frog with my free hand and wandered back to where Steve had left our hired Landcruiser: bogged up to the axles in the soft roadside sludge.

We had been following a map to the “Lost City”, scrawled on a take-away order pad by a gnarly-toothed cook at Cape Crawford’s “Heartbreak Hotel”. (This sentence is entirely true and gives me great pleasure to write). I had hoped to see the exceedingly elusive Carpentarian Grass-wren there, but like Grass-wrens, Lost Cities are difficult to find. Renee planned to make a 200 km push down and back the Tablelands Highway that night so our search for the Lost City was truncated in favour of beginning the evening’s driving. Our U-turn was truncated on the shoulder of the highway, which had been under floodwater for the last 3 or 4 days and needed little persuasion to engulf the hired Landcruiser.

We had been stalking 300 kms of the Carpentaria Hwy for the last two nights and had seen one car in that time. It was 5.30pm on Sunday and we had enough food and water in the car to last us a few nights should it come to that, but in a great fluke of variance the next 30 minutes sent us three different cars. Our eventual saviour rocked up in a big old Landcruiser. As a spry indigenous woman jumped out of the passenger seat to retrieve a rope from the tray, a man as weathered, wide and red as our fair country hopped out of the driver’s seat. Our saviour was in a hurry, the rope quickly linked our cars back to back and he barked some instructions to an unsure Steve behind the wheel of our stricken vehicle. Soon wheels were spinning as his truck revved and squealed, switching about like a hooked barramundi. Steve eventually found 4WD, low range, reverse and our steed was yanked backwards from the muck.

Impeded on the Carpentaria Hwy

Impeded on the Carpentaria Hwy

That was the beginning of one of the most eventful evenings of the trip. We were now running a bit late, but counted ourselves lucky to have gotten away with an hour delay. The drive ahead saw us traveling south down the Tablelands Highway, a road that splits rocky cliffs of rust red upon which the ivory white bark of eucalypts is thrown into dramatic contrast by the light from the setting sun. We stopped on a vast flat grass plain after dark and watched the moon rise, a giant languid yellow disc that was to light the rest of our evening.

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It is worth mentioning that I only refer to the roads by name because there are so damn few of them here in the Top End. Each road takes on a character through its interaction with the elements, the lansdscape, and the idiosyncrasies of the disparate roadhouses, towns and remote communities it links across vast distance. These bitumen ribbons of country and the hours spent on them forms a large part of the Top End experience for residents and visitors alike.

Soon after dark the animals started throwing themselves in front of the car. A remote wet season highway at night is chaos. I’ve never seen so much wildlife ever, and you’ll be pleased to know most of it survived. Bustards, nightjars, owls and curlews appear in the headlights, I brake and they make a flapping flash in my periphery as they fly within centimetres of the windscreen. Agile wallabies bound in groups across the road ahead, or sometimes they just stand on the road shoulder, waiting for us to drive closer before darting out into our path. The road is littered with frogs, only discernable as the car drives on over them. But one can’t look out for them as it is much more important to spot the groups of Brahman cattle from a distance safe enough to slow down. At several points we’re slowed to sub 10 km/h as dozens of cows slowly bumble down the road in front of you for hundreds of meters. There is nothing to do but travel along behind until they find a spot to vacate the bitumen. In addition to the fauna there’s water to watch for, the road is flooded in some points up close to a meter, and the floods have dragged onto the road a flotsam of logs, branches and general crap to drive around.

Tablelands Hwy denizen with biologist for scale - Black-headed python

Tablelands Hwy denizen with biologist for scale – Black-headed python

When we swapped drivers I had run over what I was horrified to hear Renee later estimate as a total of 30 burrowing frogs. At the wheel, Steve the frog lover perhaps avoided a few more than I did, but unfortunately he was unable to avoid a nail tail wallaby. The nail tails are beautiful creatures up close, covered in soft, fine light caramel fur with faint white markings. A dark dorsal line runs from the back of their neck down their spine to the nail protruding from a spray of thick black bristles at the end of the tail.

That was one day in gulf country, out near Boroloola.