Why do magpies swoop?


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Why do magpies swoop?

00:01:45

  Last updated September 14, 2018 at 2:44 pm

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Any cyclist could be forgiven for feeling threatened by magpies. Being attacked by a barrage of flapping wings causes even the most rational of us to scream in terror.


“They’re very impressive birds. They’ve got a big presence,” says their spokesperson, Professor Robert Magrath from The Australian National University, an expert on bird social behaviour.


And for about five weeks from the beginning of September every year, magpies make their “big presence” felt on the heads of any passing cyclist, the reason for their fame.


“Someone can go past on foot and they’ll be completely ignored, and someone will come down on a bike and they’ll get the full fury of the local group of magpies,” Professor Magrath observes.


“A bike is the size of a large threatening mammal—well, it is a large threatening mammal—and moving quite quickly, and something moving quickly might often be a predator,” Professor Magrath explains.


“The magpies perceive that there’s threat to their chicks and they respond aggressively to that threat.”


So it’s a case of taking over protective parenting a bit too literally.


But why, since cyclists don’t tend to ride their bikes up trees and steal magpie chicks, do magpies feel the need to be so defensive about a threat that has never happened? Turns out they’re in too deep to stop.


“If you put yourself inside the mind of a male magpie, a fast-moving large predator comes in their territory, they dive-bomb and it goes away so they’re very successful. And each year the same thing happens and they successfully drive away dozens of bicycles every year so in that sense there’s no particular reason for them to think it’s an unsuccessful strategy.”


Professor Magrath’s advice is not to take it personally.


“Just recognise that the magpies are just protecting their family basically. They’re not evil in any sense. They’re doing exactly what humans would do. If you perceived a threat to your children, you would behave in a way to chase the threat off.”


Given that magpies are just doing their jobs are parents, there’s an easy solution for the cyclist who doesn’t appreciate their attention.


“One trick is simply to get off your bike and there’s a good chance the magpie will stop attacking you.”


Easier said than done, though, under a barrage of beaks and flapping wings.


“It is,” Professor Magrath laughs. “I usually ignore my advice and just pedal faster.”


This article was written by Tabitha Carvan for the ScienceWise blog. ScienceWise is all about sharing the impact that STEM (science, technology, engineering and mathematics) has on our lives, and is proudly supported by the Australian National University.



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