Erin McKeown’s remarkably prolific career (six albums in eight years and thousands of shows) all traces back to one crucial moment during her freshman year of college.

“I was going to be a scientist. I was going to study birds. I went to nerd kid science camp and everything,” said the 30-year-old McKeown. “Then I got to college, and within weeks music had taken over my life. I knew almost immediately that’s what I wanted to do.”

McKeown graduated with a degree in ethnomusicology instead of ornithology, all the while working very hard to learn multiple instruments. McKeown switches among guitar, mandolin, keyboards and more with startling ease; you can tell she has done her homework.

As soon as she was done with school, she hit the road and hasn’t looked back, beginning with 1999’s “Monday Morning Cold” and jumping over genres, styles and approaches up until her most recent release, 2007’s live album “Lafayette.” She’ll bring her theatrical, energetic live show to the Grand Theatre in Ellsworth tonight.

McKeown’s work runs from the clever, catchy folk rock of her early albums to “Sing You Sinners,” her 2006 collection of covers of jazz standards, delivered in her distinctive, warm mezzo-soprano.

“I happen to know a lot about a lot of musical styles, and I spent a long time working on being a good enough musician that I can play whatever I want,” she said. “It just comes out of my head.”

Though there are traces of Afro-pop, electronic music and punk in her songs, she takes a lot of her musical cues from pre-war styles, such as vaudeville and Tin Pan Alley. She studied the former while pursuing her degree at Brown University.

“Those songs have story structures. They have an arc somewhere. They have a purpose. They move along the action in the show,” said McKeown. “I like the humor in it, too. It has a great energy, and that’s an offset to the ponderous nature of a lot of music. I try to present my music in the same way, and keep it entertaining.”

Clearly, McKeown’s one smart cookie. Her observant, literate lyrical edge and wide-ranging, kitchen-sink approach to music makes her albums an engaging listen. And let’s not forget the live show, documented beautifully on “Lafayette.” Though typically she tours with her six-piece Little Big Band, tonight’s show at the Grand will be a special affair.

“I have a really great band for the Ellsworth show. It’s unique,” she said. “Allison Miller is playing drums, and Sara Lee, who’s played with the Indigo Girls and Ani DiFranco and a bunch of other fantastic people, is going to play bass. I rarely play with a bass player, and it’s a power trio that’s all ladies. It’s so rare that you get three women onstage, unfortunately. I’m psyched.”

Erin McKeown will play at the Grand Theatre in Ellsworth tonight. Opening for McKeown is songwriter Bitch, formerly of Bitch & Animal. Tickets are $15 at the Grand box office, and the show starts at 7:30 p.m. For information, visit www.erinmckeown.com. Emily Burnham can be reached at eburnham@bangordailynews.net.