A man has died while trying to avoid a swooping magpie in a park near Wollongong which has a history of attacks.

The 76-year-old was riding his bicycle in Woonona on Sunday morning when the bird started to swoop so he rode off the path in an effort to escape.

He then crashed into a fence post, was thrown to the ground and suffered serious head injuries.

Locals performed CPR on him until an ambulance arrived, before he was airlifted to St George Hospital in a critical condition.

Despite medical efforts he died last night.

Local resident Jason Crosskey saw the accident and said the man looked to be in a "pretty bad way".

"There was quite a lot of blood," he said.

"I feel sorry for him, for something like that to happen is pretty alarming actually."

NSW Police are investigating the incident and a report will be prepared for the NSW coroner.

The man had been riding alongside Nicholson Park where locals say a particularly aggressive magpie has been a repeat offender.

The Magpie Alert website, which tracks swooping magpies across Australia, shows around eight attacks in the area.

A warning sign near Nicholson Park in Woonona. ( ABC News )

Those who have logged attacks on the website say one bird is "very determined".

"It is amazing how far it will roam from the nest to chase a chosen victim," Ken said on Magpie Alert.

Mr Crosskey agreed that one bird in the area seems to be the culprit.

"It swoops quite a lot of people. It swooped a kid yesterday."

More warning signs to be installed

The notorious stretch of cycleway is right outside the Woonona Surf Life Saving Club and president Kevin Crick said the bird had been in the area for years.

"He's here every year and the surf club just puts up with him — some of the kids treat him as a mascot," he said.

But Mr Crick said cyclists were not receiving adequate warning about the bird's aggressive nature.

"Where the sign is, it's on a blind corner and he likes to attack people heading north rather than to the south, [so] by the time you see the sign he's already swooped you," he said.

A Wollongong City Council spokesperson said the council would now place more warning signs and decals along the shared pathway.

The spokesperson advised people to contact the council directly about any "menacing" magpies.

Earlier this month the Hills Shire Council in Sydney's north east made the decision to shoot an "uncharacteristically territorial" magpie which had inflicted many injuries.

The bird was deemed a significant risk to public safety and one resident said it was responsible for giving him a heart attack during a swooping frenzy.