The 53-year-old man was riding with a small group of bikers about 6.30pm, just on dusk, yesterday when he struck a kangaroo about 30km east of Madura on remote Eyre Highway, about 1250km east of Perth.
The Kalgoorlie Royal Flying Doctor Service was called to
treat the injured biker in one of the most isolated parts of WA.
He was riding with a small contingent of motorcyclists ahead of the main Rebels group who were still on the SA side of the WA-SA border.
"He was moved by car to Madura Pass Oasis Roadhouse where staff provided first aid using their RFDS Medical Chest under the guidance of RFDS medical staff and a RFDS doctor,'' a RFDS spokesman said.
"The RFDS landed at the nearby dirt strip at 9.35pm and spent an hour at the scene stabilising him pre-flight. He was then taken to Kalgoorlie Hospital in a serious but stable condition.''
Police warning, but WA roadhouses welcome Rebels
The man is part of the Rebels, Australia's biggest bikie gang, which is crossing the WA border this morning as part of their "national run" to Perth.
Police may be warning the public, but roadhouses across Western Australia are laying out welcome mats as 1000 Rebels bikies begin the final leg of their national run into Perth.
Today the massed ranks of the Rebels were at the Border Crossing roadhouse on the South Australian/West Australian border, preparing to leave for the ride across WA for the rest of the week.
WA Police warned motorists about the mass of motorcycles,
which are being followed by around 200 police, as they travel through Eucla,
Norseman and Kalgoorlie before hitting Great Eastern Highway into Perth.
Police said they are anticipating the group to arrive in the city on Friday.
But before that, roadhouses along the route are hoping for an economic boost from the demand for fuel, cigarettes and food from the bikies, and their police escort.
``We have lots of hot food, lots of cigarettes and lots of staff all ready to go,'' said Ross, who works at the Caltex petrol station in Norseman.
``The word we are getting is that there will be 1000 Rebels and 200 police. We have got about 20,000 litres of fuel waiting for them, and we will treat them like we treat anyone else.''
The bikies are tipped to stay at the Norseman racecourse tonight before heading off again on Wednesday.
As WA police launch the state's biggest security operation since the arrival of the Queen in 2011, they have already warned the bikies they will not be permitted to enter any pubs or clubs during their time in the state.
Sergeant Gerry Cassidy said the motorbikes could be so loud they had the potential to affect road users' concentration.
``Consider using designated rest areas or comfort stops along the road until the group has passed,'' Sgt Cassidy said.
“Short term delays as the group travel along the planned route may also occur,” police said.