Saxophonist Joe Lovano always seems to have a lot of projects going on. One of them, Us Five — comprised of Lovano, pianist James Weidman, bassist Esperanza Spalding, and drummers Otis Brown III and Francisco Mela — released their debut, Folk Art, in 2009. That album included all Lovano originals, but the group’s follow-up, Bird Songs, features inventive versions of Charlie Parker compositions, a cover of the standard “Lover Man,” and “Birdyard,” which draws on “Yardbird Suite.” Lovano’s arrangements sometimes use a bar or two of a Parker original and turn them into a riff; improvisation gets set against repetition and it’s a striking effect. (Check out “Passport” and “Moose the Mooche” to see how this strategy works.) The two-minute “Blues Collage” combines three Parker tunes: “Carving the Bird,” “Bird Feathers,” and “Bloomdido.” How? By having piano, sax, and bass each play a different song, creating a woozy sort of layering that intrigues. The best thing here might be “Ko Ko.” The two drummers swing fiercely as they create a whole lot of rhythm for Lovano to play off of. It’s a wonderful reading of bebop through a free-jazz lens.