For most of the year, the black and white songbirds are not aggressive but for the four to six weeks when they nest, they will defend their young vigorously.

This is usually between August and November.

National Parks and Wildlife Service (NPWS) area manager Mark Fosdick said magpies were just really overprotective parents.

“For much of the year, these birds are a much-loved member of our community with their song and inquisitive nature, but come breeding time, the need to protect their family can make them aggressive,” he said.

“The aggression towards humans usually starts after the eggs are laid, increasing until the fledglings are almost ready to leave their nest.

“It’s actually the male that does the swooping, but less than a quarter of all males are known to swoop.”

For those people walking past a nest, the magpies often fly low and fast over the person, clacking their bills as they pass overhead.

The National Parks and Wildlife Service (NPWS) said the experience could be alarming, but it was only a warning.

Only occasionally will a bird actually strike the intruder on the head with its beak or claws. If this is unusual behaviour persists, there are ways of reducing the risk of physical injury to humans..

Magpie attacks occurred recently at the Gunnedah Gallop, where several competitors were swooped at and even injured during an attack.

Common places for them to nest are around the Stock Road area, Gunnedah Pool and Wandobah Road.

If a magpie swoops at you, some of the actions the NPWS recommends are to walk quickly and carefully away from the area; wear a bike or skateboard helmet or sunglasses; do not provoke the birds and carry an umbrella, stick or small branch above your head.

Being territorial birds, up to 10 magpies will sometimes group together in a “tribe” to defend their home. However, most territories are “owned” by a male and female pair.

A territory will have sufficiently reliable feeding and watering areas, and tall trees for shelter and nesting. Usually, there are fewer males than females in a group.

Magpies are protected throughout NSW, and it is against the law to kill the birds, collect their eggs, or harm their young. If you feel a magpie is a serious menace, it should be reported to your local council or the nearest NPWS office.