Birds have no knowledge of humans' diatonic scale. They sing using every possible pitch of the octave. Microtonal guitarist Jon Catler found in bird songs a source of inspiration and with the help of soprano Meredith Borden put together this beautiful collection of art songs. His just intonation guitar gives him access to 49 notes per octave. Many pieces are limited to guitar and voice, but Brad Catler (percussion) and Andrew Bolotowsky (flute) join in at times. Birdhouse is very different than the 1996 Catler Bros. CD Crash Landing (which also featured brother Brad, but on bass). There remain traces of jazz in Birdhouse, especially in pieces like "Scrub Jay" and "Baltimore Blues." Otherwise the music here gets much closer to contemporary song than to the warped jazz-rock performed by the power trio. The thanks in the liner notes addressed to LaMonte Young, Ivor Darreg, Harry Partch, Olivier Messiaen, and Joe Maneri give a good idea of the woods these birds prefer. Borden doesn't mimic birdsongs, her operatic singing casts them into a different light. Catler's accompaniment is often delicate and reserved. "Bird of Pray," the longest track at eight and a half minutes, is a slow incantation, repetitive and climactic with a Native American flavor. The chorus, "Lay your weapon down/The war is over," gracefully reminds listeners of the symbolism attached to the dove, the antithesis of the bird of pray. Although highly uncharacteristic of the album, it nonetheless represents a highlight. The harder-edged "Hoboken Bird," "Wood Thrush," and "Silence of the Songbirds" are also worthy of any art-song-fan's attention, but those looking for Catler's chops should begin with Crash Landing. Recommended.