Why do Australians put zip ties on their bike helmets in spring?
From September to November in Australia, male Australian magpies (Gymnorhina tibicen) defending their nests can swoop down from behind and peck at people’s heads. Anyone who comes close to a nest can become a target — roughly within 100 m for cyclists and 50 m for pedestrians. Bike commuters, postal workers, students: all pass through the same spring streets.
Each year, city residents prepare for this season by threading cable ties, or zip ties, upward through the vents of their bicycle helmets. Four or five plastic strips rise about 30 cm above the helmet, so the magpie’s beak hits the strips before it reaches the helmet surface. Some people also draw two large eyes on the back of the helmet with a black marker. Magpies tend to swoop less often when they feel they are being watched from the front.
On the citizen-run site magpiealert.com, more than 5,000 incidents are reported each year, and local councils place yellow warning signs near nesting sites. Some cities mark spring by looking at cherry blossoms. In Australian cities, spring can mean putting cable ties on helmets.