Five things we’ve learnt about water in the Pilbara


Home to some of the most stunning Australian landscapes, the Pilbara region and its inhabitants can only survive this extreme environment by understanding the scarce water supply.

Last week the world watched on as NASA announced the discovery of flowing water on Mars. This week we’re analysing water on a patch of red dirt a little closer to home.

The Pilbara – a 500,000 square kilometre stretch of land that’s home to 50,000 people in northern Western Australia. It’s hot, dusty… and full of minerals. The region’s high-grade iron ore deposits, significant deposits of gold, manganese, copper and uranium, not to mention the offshore gas reserves, make it one of the world’s most important resource regions.

It’s also a region that is rich in environmental and cultural values, and has significant areas of grazing land. Whether it’s the vast reserves of iron ore, the spectacular diversity of plants and animals, or some of the oldest living Indigenous cultures in the world, there’s one resource they all depend on — water.

Front-Hamesley Ranges

The Hamersley Range stretches across the Pilbara region and includes some of the world’s oldest rock formations.

That’s why we joined forces with the Government of Western Australia and BHP Billiton to conduct the biggest study into the water resources of the Pilbara, ever – it even has a catchy name: the Pilbara Water Resource Assessment.

It took three years and dozens of researchers, but we now have a body of knowledge that will help guide water planning and management for the Pilbara into the future.

Here are some of the interesting things we’ve learnt:

1. Ten times more water can evaporate in the Pilbara than falls as rain

Because of the blistering extreme heat in the Pilbara, surface water doesn’t last long. The Assessment found that the potential evaporation exceeds annual rainfall by 6 to 14 times, depending on the location within the Pilbara. Despite this, fresh water sources are quite common throughout the region.

2. Groundwater is the most important water source

This is a bit of a no brainer when you consider the first point. Groundwater is currently the main water resource used by towns and industry. This groundwater is not only vital to communities, but it also supports a range of ecosystems, usually near river pools and springs. These ecosystem include species of Acacia found nowhere else, one of the richest assemblages of reptiles in the world, and some of Australia’s iconic mammals – such as the northern quoll and greater bilby.

The greatest variety of ecosystems which depend on groundwater were found in the Hamersley Range.

Ecosystems are supported where groundwater is discharged to river pools and springs

It might be picturesque, but for the ecosystems of the Pilbara the groundwater discharged by these river pools and springs is absolutely vital for survival.

3. We know what it takes to make a stream flow

Between 8 and 30 mm of rain is required for runoff to occur in most Pilbara catchments, which makes the streams and rivers flow. This is important because runoff is the main way the region’s aquifers will be recharged with water. The runoff leaks through streambeds into shallow aquifers just under the surface and from there is able to replenish deeper aquifers, which can store large quantities of water within inland areas.

4. The Pilbara is almost certainly getting hotter

Despite the uncertainty inherent in predicting future climate, there’s one thing that all the Global Climate Models used in this study agree on – the Pilbara is getting hotter. The assessment team used the same modelling tools used by the Intergovernmental Panel on Climate Change to determine what the future climate might look like in the Pilbara. The models project temperatures will be about 1°C warmer by 2030 and 2°C warmer by 2050, compared with 1980s temperatures.

5. It is getting dryer… and wetter

The team assessed the rainfall trends for the area and found that between 1961 and 2012 the east of the Pilbara had become wetter and the west of the area had become drier. They also used the climate models to predict future rainfall for the Pilbara and the models were split on whether the future would be warmer and drier, or warmer and wetter.

Rainfall in the Pilbara results from both tropical weather processes from the north and temperate weather processes from the south. This makes it difficult to predict future rainfall trends for the region because the modelling suggests these processes will respond differently to any increases in greenhouse gases into the future.

On balance, the climate projections carried out by the Assessment team indicate the Pilbara may become slightly drier by 2030 and 2050. But they’re not ruling out the potential for a wetter future either — they modelled a range of wet and dry future scenarios so water managers can be prepared.

If this makes you thirsty for more information about the Pilbara’s water check out the Assessment’s final reports. You can also enjoy a selection of images from this stunning region in the gallery below.

The Pilbara Water Resource Assessment was funded by CSIRO, the Government of Western Australia and BHP Billiton. The project was led by CSIRO and overseen by officers from the Department of Water, BHP Billiton, the Pilbara Development Commission and the Water Corporation.

Media contact:

Chris McKay | +61 7 3833 5728 | +61 455 085 247 |

A game of hives: Fatal fighting in native bees

“When you play the game of hives you win or you die.” True in Game of Thrones, true for bees. Image Paul de Barro

By Fiona McFarlane

Who would have guessed that our own backyards might be a battlefield for bees?

And that these deadly skirmishes involve aerial battles lasting days, with hundreds of fatalities from both attacking and defending sides, ousting the helpless from the hive and culminating in the eventual overthrow of the resident queen and installing their own in her place.

A cluster of dead native bees on the ground in a Brisbane backyard was enough to convince a group of scientists to dig deeper into this unusual behaviour of the Australian native bee species, Tetragonula carbonaria.

Their further investigations led to a surprising discovery, that the study colony was not only being attacked by its own species but also by a closely related species, T. hockingsi.

A fight to the death

Fatal fighting is rare in nature, but not with our native fighting bees.

Fatal fighting is rare in nature, but not with our native fighting bees. T. carbonaria squabble over a bouganvillea. Image: Paul de Barro

Prior to this study, only the one species of bee, T. carbonaria was known to engage in battles between neighbouring colonies involving mass fatalities but this study provides the first evidence of fatal fighting between different species.

Fighting to the death or ‘fatal fighting’ is relatively rare in nature. Evolutionary biologists propose that this is because species have evolved different ways to assess strength and fighting ability that doesn’t involve the loss of the individual.

In species where fighting does escalate to death, scientific theory predicts the risk of death is outweighed by the benefits being obtained, such as fighting for scarce food resources, mates or nest sites.

Fatal fighting has been well studied in ants with beneficial outcomes including slave-making, raiding of nest supplies and gaining access to new food sites.

In the case of the T. carbonaria, the researchers hypothesised that the fighting swarms were most likely attempts at taking over neighbouring hives.

To test their hypothesis, they made regular observations on the ‘study’ hive in the backyard and collected the dead bees after fights for analysis. Using modern molecular techniques they were able to track which group of bees were attacking and which were defending. It was this analysis that lead to the surprising discovery that the attacking bees were in fact a separate species.

Following a succession of attacks by the same T. hockingsi colony over a four-month period, the defending T. carbonaria colony was defeated and the hive usurped, with the winning colony installing a new queen.

Hijacking Hives

The Iron Comb? Australian native bee hives seem to be worth going to war over. This is a top view of a Tetragonula carbonaria hive. Image: Tim Heard.

To ensure that what had occurred at the study hive was not a one-off event, our researchers monitored the colonies of over 260 commercial T. carbonaria hives over a five-year period, recording any changes in species through changes in hive architecture (see note).

They found evidence of 46 interspecies hive changes (via the change in hive architecture) during the five year period, which were most likely to be usurpation events.

There is still much to be learnt about these small creatures, such as what instigates the attacks how and when the invading queen enters the nest, and whether the young in the usurped hive are spared and reared as slaves, or killed outright.

In the case of our native bees, it is thought that the capture of a fully provisioned nest (including ‘propolis’, pollen and honey stores) is a sufficiently large benefit that it outweighs the loss of so many lives.

Let’s ‘bee’ clear, we still need further research

The researchers are quick to point out that this is an excellent example of how little we actually know about small stingless bees, which can be an excellent and resilient alternative pollinators to declining honey bee populations.

NOTE: T. carbonaria has a brood chamber, in which cells are even and connected by their walls to adjacent cells at the same height, whereas T. hockingsi brood chamber takes on a less organised appearance, being an irregular lattice comprised of clumps of around ten cells connected by vertical pillars.

Find out more about our work leading the Global Initiative for Honey bee Health and the research we are conducting with bees.

Fantastic Fathers: Australian wildlife edition

The stay at home dad: Emperor Penguin dads share the incubation duties.

The stay at home dad: Emperor Penguin dads keep the kiddies warm and they even lend a hand with incubation duties. Image:

By Minky Faber

This Sunday, right around Australia, many fathers will be waking up to breakfast-in-bed, the obligatory socks ‘n’ jocks set and gift vouchers to that megastore they love to visit. Father’s Day is when we can proudly show our fathers how much they mean to us, and to say “thanks for being awesome, Dad!”

While every species in the world has their dud-dads, humans can be proud that our fathers are generally pretty good at this parenting lark. They share the child-raising responsibilities, they provide priceless life advice, pay for stuff and open stubborn jars.

For the rest of the animal world, the majority of dads aren’t so awesome. Some males are merely egg fertilisers, engaging in zero interaction with their eventual offspring. While other dads are just ruthless and will straight up kill their own young (or the young of an overthrown dominant male).

But because it’s Father’s Day we don’t want to dwell on the fiendish fathers of the animal kingdom. Instead, we want to shine a light on some of the ‘Wonderdads’ of the Australian wild …

Mum might be off speed dating, but dad can be relied on to take care of the little ones.

Mum might be off speed dating, but dad can be relied on to take care of the little ones.

Emus (Dromaius novaehollandiae)

It all starts out like any other relationship: they see each other from across the bushland, they meet, they build a nest together, they do some elaborate dancing rituals during courtship, they mate, and soon enough the female is laying 5-15 large dark green eggs on the ground… But then she realises that it’s a big country out there, with plenty of other Emu fellas to meet, so she leaves… Leaving our long-legged Emu dad (who has become rather aggressive and possessive and probably needs to be left alone) to sit on the eggs for around 55 days.

He ends up losing weight due to being unable to eat and may even forgo a toilet break during the incubation period. Finally, he is greeted by a bunch of striped babies that will stay with him for up to 6 months and he’ll teach them to forage and survive.

Giant Water Bugs (Belostomatidae family)

Q: What did the Mum Bug say to the Dad Bug?

A: “I larva you!”

We were only going to get so far in this article without a dad joke. Which brings us to one of the few good dads in the entomological world: the Giant Water Bug. This species can be found in the still waters of Australia and the Indo-Pacific and can grow to seven cm in length. Not only does the male carry all the fertilized eggs upon his back, he strokes them lovingly with his back legs to ensure a steady flow of fresh water passes over them. After three weeks the eggs hatch and the egg cases will eventually fall off the male’s back.

Abedus indentatus male with eggs on its back

Kids take note, if Dad refuses to give you a piggyback, kindly remind him that he’s appearing lazy compared to this amphibious father! Image: Wiki Commons

Emperor Penguins (Aptenodytes forsteri)

Makin’ babies is hard work… Ok not the initial part, but the actual production of a hard egg and expelling that hard egg (or soft baby) takes time and a physical toll on the female’s body. The Emperor Penguins of Antarctica are all for sharing the burden of raising children. So when the exhausted mama penguin needs to recover, it’s time to bring in the stay-at-home dad.

With some close shuffling, the mother carefully transfers the egg from her feet to the feet of the father for the next 65 days (yep that’s a 65 day fasting period for the dads!). Finally the babies hatch and the fathers will huddle together in huge groups, taking turns to be in the middle for extra warmth, and feeding their little bundle of joy with a regurgitated substance.

Clownfish aka Anemonefish

There was one minor detail left out in the story of Finding Nemo: Nemo’s Dad probably become a female after Nemo’s Mum was suddenly taken by a Barracuda. You see, clownfish are what’s known as sequential hermaphrodites meaning all clownfish babies are born male and within a dominance hierarchy. There exists only one female in a group of clownfish, and she will mate with only one sexually mature male. But once she’s out of the picture, the dominant male will become the breeding female and the remaining males will level up in the hierarchy. The females will provide minimal care to the clutch of 100-1000 eggs while the breeding male will devote his time to guarding, physically fanning the eggs, and keeping the nest tidy until they hatch.

Common name: Orange Clownfish. Scientific name: Amphiprion percula. Family: Pomacentridae.

Clownfish Father’s care for over 100 eggs at a time. Image: Vanessa Hill via

So here’s to all the great fathers out there, human or otherwise. Thanks for the piggybacks, warm hugs, protection, guidance, and mandatory dad jokes that come with the title.

Want to learn more about our Australian fauna? The Atlas of Living Australia is a great place to discover more about Australian plants, animals, and fungi – you can even use the powerful mapping tools to discover all the species to be found in your local area.

From desolation to illustration: Children’s book reveals how Phasmids escaped extinction

Quite a survivor, the Phasmid has returned from the brink of extinction to star in its own Children's book. Image: Granitethighs CC BY-SA 3.0

Quite a survivor, the Phasmid has returned from the brink of extinction to star in its own children’s book. Image: Wiki/Granitethighs CC BY-SA 3.0

When you think of extinct animals, what comes to mind? The Javan Tiger? The Dodo? The thylacine (Tasmanian tiger)? Sadly, there are too many creatures disappearing from our planet. This is why the story of Phasmid, or the Lord Howe Island Stick Insect, is so special – and why it’s being told in a new children’s book.

Believed extinct for nearly 80 years, due to the introduction of Black Rats, the Phasmid was rediscovered in 2001 on Ball’s Pyramid – a rocky volcanic out-crop, 23 kilometres off the coast of Lord Howe Island. And thanks to Melbourne Zoo’s recovery breeding program, this wingless nocturnal creature is slowly crawling back from total extinction.

The re-emergence of this plucky insect was cause for celebration and made headlines around the world. The tale of survival was so impressive that two of the world’s foremost naturalists, Dr Jane Goodall DBE and Sir David Attenborough, visited Melbourne Zoo to see the Phasmids for themselves.

Today, on the anniversary of the first-ever hatching of a Phasmid nymph at the Zoo, a new illustrated children’s book has immortalised the incredible tale of the Phasmid’s survival.

The book, titled Phasmid: Saving the Lord Howe Island Stick Insect, was written by Melbourne Zoo Invertebrate Keeper Rohan Cleave, and illustrated by renowned artist Coral Tulloch. The book reveals the life cycle of the world’s most critically endangered invertebrate, from beginning life as an egg, to hatching into a diurnal nymph and growing into a nocturnal adult.

The author of the book continues his work with the Lord Howe Island Stick Insect at the Melbourne Zoo, and so far the results have been promising. In fact, in the last 12 months over 1,300 phasmids have been bred in captivity; no small feat considering, at one stage, there were only 20 or 30 left in the wild.

To find out more about the courageous struggle for existence of the Phasmid, do yourself a favour and take a look at the sumptuously illustrated children’s book, Phasmid: Saving the Lord Howe Island Stick Insect.

Seabirds are eating plastic litter in our oceans – but not only where you’d expect

albatross marine debris

Chris Wilcox, CSIRO; Britta Denise Hardesty, CSIRO, and Erik van Sebille, Imperial College London

Many of you may have already seen the photograph above, of an albatross carcass full of undigested plastic junk. But how representative is that of the wider issue facing seabirds?

To help answer that question, we carried out the first worldwide analysis of the threat posed by plastic pollution to seabird species.

Our study, published today in Proceedings of the National Academy of Sciences, found that nearly 60% of all seabird species studied so far have had plastic in their gut. This figure is based on reviewing previous reports in the scientific literature, but if we use a statistical model to infer what would be found at the current time and include unstudied species, we expect that more than 90% of seabirds have eaten plastic rubbish.

Rising tide of plastic

Our analysis of published studies shows that the amount of plastic in seabird’s stomachs has been climbing over the past half-century. In 1960, plastic was found in the stomachs of less than 5% of seabirds, but by 2010 this had risen to 80%. We predict that by 2050, 99% of the world’s seabird species will be accidentally eating plastic, unless we take action to clean up the oceans.

Perhaps surprisingly, we also found that the area with the worst expected impact is at the boundary of the Southern Ocean and the Tasman Sea, between Australia and New Zealand. While this region is far away from the subtropical gyres, dubbed “ocean garbage patches”, that collect the highest densities of plastic, the highest threat is in areas where plastic rubbish overlaps with large numbers of different seabird species – such as the Southern Ocean off Australia.

Expected number of seabird species ingesting plastic. PNAS

Seabirds are excellent indicators of ecosystem health. The high estimates of plastic in seabirds we found were not so surprising, considering that members of our research team have previously found nearly 200 pieces of plastic in a single seabird. These items include a wide range of things most of us would recognise: bags, bottle caps, bits of balloons, cigarette lighters, even toothbrushes and plastic toys.

Seabirds can have surprising amounts of plastic in their gut. Working on islands off Australia, we have found birds with plastics making up 8% of their body weight. Imagine a person weighing 62 kg having almost 5 kg of plastic in their digestive tract. And then think about how large that lump would be, given that many types of plastic are designed to be as lightweight as possible.

The more plastic a seabird encounters, the more it tends to eat, which means that one of the best predictors of the amount of plastic in a seabird’s gut is the concentration of ocean plastic in the region where it lives. This finding points the way to a solution: reducing the amount of plastic that goes into the ocean would directly reduce the amount that seabirds (and other wildlife) accidentally eat.

That might sound obvious, but as we can see from the stomach contents of the birds, many of the items are things people use every day, so the link to human rubbish is clear.

Plastic from a dead flesh-footed shearwater, amounting to 8% of the bird’s body weight. Britta Denise Hardesty, Author provided

Our study suggests that improving waste management would directly benefit wildlife. There are several actions we could take, such as reducing packaging, banning single-use plastic items or charging an extra fee to use them, and introducing deposits for recyclable items like drink containers.

Many of these types of policies are already proving to be locally effective in reducing waste lost into the environment, a substantial portion of which ends up polluting the ocean.

One recent study of industrial practices in Europe found that improved management of plastic led to a clear reduction in the number of plastic items found in seabirds in the North Sea within a few decades. This is encouraging, as it suggests not only that the solutions are effective, but also that they work in a relatively short time.

Given that most of these items were in someone’s hands at some point, it seems that a simple behaviour change can reduce a global impact to our seabirds, and to other marine species as well.

This work was carried out as part of a national marine debris project supported by CSIRO and Shell’s Social investment program, as well as the marine debris working group at the US National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, with support from Ocean Conservancy.

The Conversation

Chris Wilcox is Senior Research Scientist at CSIRO; Britta Denise Hardesty is Senior Research Scientist, Oceans and Atmosphere Flagship at CSIRO, and Erik van Sebille is Lecturer in oceanography and climate change at Imperial College London

This article was originally published on The Conversation. Read the original article.

Australia: riding on the insect’s back


Love me tender: the giant northern termite, an endemic species living in tropical Australia. 

David Yeates, CSIRO

As you may have spotted, the title of this article is a cheeky reference to the famous saying that Australia rides on the back of a particular woolly ruminant. The reference dates back to 1894, when the wool industry was one of the primary sources of Australia’s prosperity.

Wool was our main export commodity from 1871 to the 1960s. For more than a century, the golden fleece drew pastoral workers and professionals to regional Australia, and sustained many a country town.

It is likely that most people would consider the native birds and animals in the farm shelterbelt to be the main source of agricultural biodiversity. However, the most diverse and important biodiversity is much smaller. And it’s invertebrate.

Looking beneath the farmer’s feet we would find countless insects and other invertebrates living out their lives, and in so doing providing services that we take freely and for granted.

Beneficial bugs

While Australia long ago hopped off the sheep’s back, insects and other invertebrates still do things that sustain our society. Yes, “sustain”. In recent years, agricultural economists have put estimates on the values of some of these insect services to human society.

In one 2009 example, the total economic value of insect pollination of agricultural crops worldwide was A$220 billion. A sizeable fraction of this pollination occurs in Australia by species such as the European honeybee, and many thousands of native bees and flies.

Insects are a bit like car keys, you only notice them when they are missing. During the mid noughties, honeybees died in large numbers in Europe and the United States, a phenomenon known as colony collapse disorder (CCD). The cause of CCD is complex and not yet fully understood.

But the effects were transparent. Profits from pollinated crops, such as almonds decreased. The prices of some foods increased significantly, because farmers had to pay more for disease-free bees, often importing them from CCD-free Australia.

Honey bee hard at work boosting agricultural productivity. Bob Peterson/Flickr, CC BY-SA

Another good example is the service that introduced dung beetles provide. Australia’s cattle herd was estimated at 30 million in the 1970s, each animal producing 10 pats per day, covering over 2.5 million hectares of pasture each year.

Millions of bush flies (Musca vetustissima) also bred in the dung. Overseas these dung pats would have been recycled into soil nutrients by the local dung beetles that buried small chunks of the dung in the soil to rear their young. However, Australia’s native dung beetles are adapted to feed on and bury dry, fibrous marsupial dung, and avoid the much more moist cattle dung.

CSIRO introduced dung beetles from Europe and Africa in the 1970s and 1980s that buried cattle dung underground so that it became a fertiliser for use by grass and other plants. The burrowing activity of the beetles also aerated the soil. And it also provided another important service: controlling the bush fly plague by removing and burying the dung that bush flies were breeding in.

Australia’s outdoor café owners probably don’t know it, but they owe at least part of their clientele to the silent work of introduced dung beetles working tirelessly in the agricultural districts surrounding our cities, once the source of most of our bush flies.

If you want to know more about the dung beetle story, watch the documentary The Great Australian Fly by 360 degree films, which can be found on ABC’s iView.

Great engineers

We often have an ambiguous relationship with insects, entire groups are prejudiced because of a few pest species. Termites are an excellent case in point. In most cases we only think of the damage they can do to timber in buildings.

Termites are impressive builders, dotting the landscape with their imposing structures. Bob Peterson/Flickr, CC BY-SA

But termites are in fact great soil engineers. They play a key role in the functioning of many tropical and subtropical landscapes, such as those found over much of northern Australia. They decompose wood and grass, and they are also social creatures, living in great colonies that sometimes produce a characteristic mound. Their region of influence in the soil is termed the termitosphere, and this is where termites are busy nutrifying, aerating, moistening and mixing the soil.

Termites are small but numerous, and their biomass can exceed 50 grams per square metre, much greater than mammalian browsers in the same environments. Because termite mounds are intense, crowded insect cities full of life, growth, decomposition, waste and death, soil nutrient levels are much higher around them – up to seven times higher in one Australian example.

Termite excavations move soil around between layers, and create tiny holes in the soil that allow air and moisture to infiltrate. Termites modify many soil characteristics, improving and increasing the productivity of soils, and they do this free of charge over much of northern Australia. Overall, the positive benefits of the termitosphere are far greater than the costs.

Hidden biodiversity

With insects being such a valuable resource, and part of the natural heritage of a first world country such as Australia, you would think that we had a good handle on our insect diversity.

The reality is very different. We have only managed to catalogue around 25% of our insect biodiversity at species level. The remaining 75% cannot be managed well because we don’t have the basic information required such as what it is, where it occurs, and what it does.

For example, there are around 260 named termite species in Australia, but this represents less than half the total number, and many of these unnamed species are represented in CSIRO’s Australian National Insect Collection. Imagine trying to manage a library without knowing how many books you had on hand, and what they were about.

In other areas such as medicine and physics we have learnt the importance of small things: germs, atoms, chemical molecules etc. We gain knowledge in these areas by reducing the system to its basic components and working on the properties of these parts and their interactions.

But in biodiversity science we are still trying to understand and manage ecosystems with only a basic knowledge of a subset of the biological components in the system. Australian ecosystems ride on the insect’s back, and we would be better off economically, socially and environmentally if we invested more in understanding our insect fauna.

The Conversation

David Yeates is Director of the Australian National Insect Collection at CSIRO

This article was originally published on The Conversation. Read the original article.

You make me wanna swoop: dispelling magpie myths

U wot m8? Not even our Canberra Deep Space Communication Complex is safe

U wot m8? Not even our Canberra Deep Space Communication Complex is safe.

With warmer weather showing signs of returning across the country, so too are many of spring’s delights: the flowering of plants, greening of trees and rolling of cuffs all testament to the fact that the worst of winter is behind us.

Unfortunately, it’s not all lamingtons and Cherry Cheer at this time of year. For there is also a suburban menace lurking just over the horizon: a black and white marauder waiting to terrorise unsuspecting picnickers, exercisers and office workers alike.

Yep, September is magpie season.


If this image doesn’t send a primordial chill down your spine, you’ve obviously never spent the month of September in suburban Australia. All around the country, roadsides, reserves and office blocks turn into battlegrounds as the Australian magpie looks to protect its patch from any and every threat it can lay its beak on.

So why do magpies swoop us humans – is it to defend their young, or their territory? Or are they just bird jerks?

And most importantly, is there any way we can guard against them?

There was an illuminating paper co-authored by academics from Deakin and Griffith universities, titled Attacks on humans by Australian Magpies (Cracticus tibicen): territoriality, brood-defence or testosterone? The paper, published in our Emu – Austral Ornithology journal back in 2010, looked to study three common hypotheses behind magpie-human attacks, particularly in suburban areas. Were the attacks triggered by territoriality, brood-defence or (magpie) testosterone, the authors asked?

The response of 10 pairs of aggressive magpies to natural levels of human intrusion was compared with that of 10 non-aggressive pairs. Behavioural observations strongly supported the contention that attacks on humans resemble brood-defence and did not support an association with territoriality. The study also found no support for the suggestion that testosterone levels correlated with aggressiveness towards humans: male testosterone peaked immediately before laying and was significantly lower during the maximum period of attacks directed at people. Moreover, there were no differences in the testosterone levels of aggressive and non-aggressive male magpies. The pattern of testosterone production over a breeding cycle closely resembled that of many other songbirds and appeared not to influence magpie attacks on humans.

So, brood-defence can be identified as the cause of attacks.

But, of more interest to posties, cyclists and small children with blonde hair in particular: what makes magpies more likely to attack some people, and not others?

Enter the brave scientists of CSIRO Black Mountain in Canberra. In 2010 (it must have been a bad year!) a particularly aggressive maggie was nesting on the foot and cycle path between the Australian National University and our Black Mountain site. With all types of magpie-repelling adornments being attached to cycle helmets with varied successes, and (figurative) public service and academia corpses littering the notorious path, our enterprising colleagues decided to add some scientific scrutiny to the debate: how do you deter a mad magpie?

The results can be seen in the following two YouTube clips that, in 2010 terms, broke the Internet.

We can’t really condone the results: we would never advise riding your bike without a helmet. But these videos also do quite clearly dispel the myth that helmet decorations do anything to stop a swooper.

And really, what’s better than seeing public servants being attacked by a magpie to the soundtrack of Tricky’s Maxinquaye?

Want to learn more about this quintessential Aussie which, September aside, we do actually really like? Then check out this great book available through CSIRO Publishing: Australian Magpie – biology and behaviour of an unusual songbird.

And remember, keep your eyes to the sky.