The native Australian birds are notorious in the spring months as they fly, clacking their beak, towards people crossing through their territory in an effort to protect their newborn chicks.

A Bathurst resident recently reported they were surprised to be swooped so early in the year on the Magpie Alert! website. The swoop occurred on the Vale Road, a popular cycling route.

"If you're a solo cyclist beware of this aggressive magpie. He let me pass then without warning or sound, he swooped from behind hitting my head and neck while squawking profusely," a person using the name Radio Addict posted.

"This one physically hits you so it may be capable of drawing blood.

"I was attacked last year with this one and it's more aggressive this time, perhaps it remembers me and has a set against me for some reason."

In Orange a Magpie Alert user called Paul.F reported he had been swooped while riding his bicycle on Mitchell Highway in Glenroi.

"Magpie swooped from short pines heading into Orange," he posted.

A National Parks and Wildlife Service spokeswoman said magpies breed between July and November and are very protective of their chicks.

"Magpies start breeding as soon as conditions are suitable including when weather begins to warm up," she said.

"Some, but not all, magpies swoop anyone they see as an intruder in their territory.

"In the vast majority of cases the swooping is simply bluff however, sometimes birds can strike people causing injuries.

"This protective behaviour lasts only a few weeks, so be prepared to avoid them, or risk being injured."

Magpies are a protected species and it is illegal to kill them, collect their eggs, or harm their young.

MagpieAlert! allows people to log on and record where they have experienced a swooping, details about the attack and any injuries suffered.