Last updated May 25, 2018 at 12:08 pm
The risk of collision is on the rise as the birds become habituated to aircraft noise.
As every schoolkid who has had the unnerving experience of being swooped by a magpie (Cracticus tibicen) will testify, they are nothing if not assertive.
New research, however, indicates that the iconic black-and-white birds might now have grown too fearless – and could be putting themselves and many human lives at risk.
At issue is the way they quickly become accustomed to types of human activities that prompt other avian species to get the hell out of Dodge.
A magpie standing on a road as a car approaches will move away seemingly at the last moment, and with no sign of panic. The trouble is, at least one population of the birds has started exhibiting exactly the same behaviour around aeroplanes – raising the prospect of disaster.
A team of researchers from aircraft and wildlife managers Avisure in Queensland and Deakin University in Victoria set out to measure the flight and danger avoidance behaviours of a tribe of wild magpies living around the Point Cook RAF Base, a small airport about 29 kilometres south-east of Melbourne that services mainly small, single-engine planes.
Led by Avisure’s Grant Linley, the researchers looked at magpies foraging in three distinct zones – near or on the runways (known as airside), around the rest of the airport, and immediately outside in an adjacent coastal park.
Individual birds in each area were selected and exposed to loud recordings of a Cessna 172 landing or taking off. A silent recording was also used, as a control.
The results were interesting. Birds in all three environments moved away at the sound of the planes, and were more likely to move quickly in response to take-off noises compared to landing noises.
People more worrying than planes
However, the speed and distance covered in the avoidance behaviours was inversely proportional to distance from danger. Magpies in the coastal park got out of the way quick-smart, but those on the tarmac took considerably more time to react, indicating that they had become habituated to the noise of the aircraft.
At the same time, birds from all three environments showed identical reactions to the presence of pedestrians. All moved away quickly.
This, the researchers suggest in a paper published in the CSIRO journal Wildlife Research, might be because aircraft are regarded by the birds as less dangerous than humans. Species become habituated to phenomena, say the scientists, that are “frequent, predictable and benign”.
“In our study system, aircraft are likely to be more common and predictable than are pedestrians,” they write.
Another possibility to account for the almost insolent response of magpies when confronted by the sound of a departing Cessna – which are small for aircraft, certainly, but still much, much bigger than a bird – is that only really tough ones hang around airside.
Inexperience proves costly
“Selection for experienced birds” may have occurred, the researchers suggest, meaning that young and inexperienced members of the species might have already been squelched by planes or runway vehicles.
And discovering the reasons behind the slow responses of magpies on runways, they go on to conclude, is of critical importance. Management strategies to move the birds on and reduce the risk of a potentially catastrophic magpie-Cessna collision will depend on whether they are exhibiting learned responses, or the end-game of selection pressures, or undergoing another process entirely.
Any strategy to reduce the risk of magpies hitting planes is at this stage wholly precautionary. Avisure maintains a database detailing every encounter between a plane and a bird or animal, worldwide, from 1912 until the present.
Magpies are not on the list. Vultures, eagles, starlings and rock pigeons are, however, along with cattle, a dog, a couple of species of deer and, bizarrely, a giraffe.