By Jessica Bakeman/ Star Tribune

Sara Bareilles played mellow tunes, dropped some f-bombs and thanked the tigers for listening to her Tuesday at the soldout Minnesota Zoo amphitheater.

Bareilles has been touring with the hit country duo Sugarland since March but headlined the soldout zoo (with opener Raining Jane) on one of Sugarland's off nights.

She asked her Twin Cities audience to bear with her as she worked out the kinks of the show, a longer performance than she and her band have played recently. It turned out that the glitches were few. The concert featured mostly ballads showing off Bareilles' clear, no-AutoTune-necessary voice, with a few show-stopping upbeat numbers like "Love Song" and "King of Anything" sprinkled in.

Bareilles mostly accompanied herself on a small piano, but she also pounded on the drums, strummed acoustic guitar or ukulele and delivered an emotional a capella "Gravity." For that, the audience was on their feet, silent.

She treated the crowd to a "world premiere" of a "brand brand brand brand brand new song." It expressed the woes of a young woman who needs to be reminded of her beauty before "trad[ing] in your summer skin for those high heeled shoes."

Bareilles mentioned many times — maybe too many — how grateful she was for the audience's support, at one point wrestling with tears before flipping back to her gimmicky humor, peppered with the f-word. (She also uttered that expletive when she momentarily forgot the lyrics in the middle of Mumford & Sons' "Little Lion Man.")

She offered a couple of explanations for her demeanor. One: "I'm sooo drunk tonight." Another: "They're checking to see if I have Tourette's [syndrome]. They're not sure."

Despite her odd (albeit entertaining) behavior, Bareilles made her audience wonder why her first album was called "Little Voice." It's just too big for that.

Here's her zoo set list:

Uncharted/ Vegas/ Gonna Get Over You/ Machine Gun /Many the Miles/ Breathe Again/ Basket Case/ Bluebird/ Little Lion Man (Mumford & Sons)/ Come Round Soon/ Bottle It Up/ Love Song/ King of Anything/Gravity(a capella)/ new untitled song/ Let the Rain

See here a user-posted video of her a capella serenade, "Gravity":