An aggressive group of magpies in Perth swarm and ambush a passing cyclist as they try to protect their offspring.

Footage from September 27 shows multiple birds swoop down and approach the cyclist as he films a selfie video.

The filmer told Newsflare: "Outside my house in Perth, Australia is a group of magpies that patrol the park and surrounding area looking to protect their babies in their nest.

"I get swooped every time I ride my bike or electric skateboard as I leave the house.

"This is one such incident.

"What you can't see in the video is my 3-year-old daughter in a baby seat sitting behind me."

It is well-known in Australia that magpies are prone to swooping at this time of year.