LAS VEGAS — The Air Force is turning toward extreme sports enthusiasts to fill a shortage of special operations troops.

They need combat air traffic controllers who go behind enemy lines to set up airfields and call in air strikes and trauma specialists who skydive into hostile territory to rescue wounded troops.

To be fully staffed, the Air Force needs 426 combat controllers. It has 350. A full complement of Air Force pararescuers is 123; there are 90.

That's one reason why recruiters visited a motocross race here to find athletic adrenaline junkies willing to serve.

Dozens of dirt bikes whine and speed and spray dirt as they soar over jumps. The crowd is young, and several young men wear casts for broken limbs.

"It's a good match for us," said Wayne Norrad, who's manning an Air Force special tactics recruiting booth at the Amp'd Mobile Supercross race. "We're looking for a person who likes a little adrenaline rush. Thrill seekers."

All military special operations forces are expanding. Since 2002, the U.S. Special Operations Command has added 6,000 people and almost doubled its budget, according to the Pentagon. There are about 17,000 special operations forces in the Army, Navy, Air Force and Marines.

"There's going to be a need for these guys over the long term," said Col. Bill Sherman, 46, of the Air Force's Special Operations Command.

Air Force Master Sgt. Robert Jeeves, 39, is a combat controller, a special operator trained as an air-traffic controller. He rode on horseback in Afghanistan and toted a 165-pound rucksack in Iraq.

"My rifle's not my best weapon; it's the radio on my back," he said. "For every kill with an M-4 (rifle), we killed 168 more with close air support (in Iraq)."

Two-thirds of Air Force special operations forces applicants wash out, Norrad says. Many can't finish underwater training.

The Air Force also must compete with better-known outfits, such as the Navy SEALs, who also need more recruits. Navy records show that elite unit is 12 percent below full strength.

The military wants to keep the special operators it already has; last year, it started offering a $150,000 bonus to 19-year veterans who sign up for an additional six years.

Air Force special operations recruiters have been to 10 Supercross races this year with an exhibit featuring satellite communication equipment, a rugged laptop and a dirt bike.

Darren Godber, 19, of Glendora, Calif., expresses interest.

"It looked pretty cool, cruising around on dirt bikes, calling in bombs," he said.