While quotation or at least evocation of bird-song is a frequent occurrence in music, no composer's music has been as permeated with it than that of Olivier Messiaen. The apex of his musical setting of birds is the present Catalogue of the Birds, a work of 1956-1958, and its pendant, the 1970 composition "The Garden Warbler."
In these works the animals' sounds are not anything like the conventional notion of musical birdsong prettiness. While Messiaen has transcribed their calls faithfully, he has made allowances for the fact that rarely do the pitches of their songs fall evenly on the lines and spaces of our musical staff. So to be true to the actual relative distances between the pitches, he will expand the range of the song (from lowest note to top note) until the "off" notes land on a note that the piano can play. For example, if a bird produced an even series of seven rising tones that occupied the space from E flat to F sharp, followed by an upward leap to a quarter-tone below the next higher E flat, he might lower the whole thing an octave or so, and produce the eight-note sequence: C, C#, D, D#, E, F, F# (leap of nearly two octaves to) B. At the same time he might decorate these notes with a clashing harmony to depict a screechy or metallic timbre in the bird's voice. If that bird is apt to call this song out five or six times, Messiaen might repeat the same pattern as many times. The end result is distinctly unusual, yet masterful in its use of contrasts of touch and timbre, choice of chord-colors, and placement of silences and reverberations. Messiaen is very precise in his indications: There are places in the score where the pianist must play chords in which most of the notes have their own individually marked loudness level. In short, the pianist must constantly be a micro-manager while always integrating the performance into a dramatic structure that can convincingly hold together.
The initial work of this type, "Catalogue des oiseaux, " is justly regarded as one of the great large-scale keyboard suites. "The Garden Warbler" is a fitting addition to it. The idiom is unusual and advanced enough that it is likely to baffle listeners who lack sufficient experience of the music of the post-World War II era.