Actor TAYLOR LAUTNER celebrated his 21st birthday by bowling with his celebrity pals KRISTEN STEWART, ASHLEY BENSON and PATRICK SCHWARZENEGGER.

The hunk, who turned a year older on Monday (11Feb13), marked the milestone in Los Angeles on Saturday (09Feb13) by enjoying a night out at posh bowling alley Lucky Strike.

A source tells UsMagazine.com, "Taylor was super nice, very polite. Everyone was having a blast... (and) super into the bowling. (Lautner) is really good."

His Twilight co-star Stewart arrived at the event just after midnight in a backwards cap and ripped T-shirt, and an onlooker says the 22 year old had a good time catching up with her former onscreen love interest.

An insider adds, "She was being fun and social, bowling and high-fiving. She and Taylor definitely seemed to be good friends and she was living it up."

Stewart, Pretty Little Liars beauty Benson, and Arnold Schwarzenegger's son all then sang Happy Birthday to the star before departing around 1:30am local time.