The common blackbird (Turdus merula) is one of the most frequently incorporated bird species in Messiaen's music. Messiaen regularly heard singing blackbirds he was walking through the streets and parks of Paris, but in case that he wanted to transcribe the birdsong, he went to small towns (Zürich, Switzerland) or his holiday home in the rural French district Dauphiné. There, he could listen more carefully without being disturbed by the noise of the city.25 The Quatuor pour la fin du temps (1940) is the first piece in which blackbird songs are incorporated, followed by Visions de l'amen (1943) and the Turangalîla-symphony (1946-48). Later, Messiaen would admit that the blackbirds of those particular works are not very accurately transcribed.26 In his words, thos transcriptions were 'very badly' and he was 'deeply mortified by [his] ignorance [of bird knowledge].'27 Because of his uncertainty, he wrote down in the score more general terms such as comme un oiseau or oiseaux.28 From the 1950's onwards, Messiaen became more convinced about his bird transcriptions, due to the help of professional ornithologists such as Jacques Delamain, Robert-Daniel Etchécopar and Jacques Penot. Looking back on his early bird trancriptions of the 1940s, he explained that oiseaux referred to blackbirds and nightingales.
When Messiaen composed the Messe de la Pentecôte around 1950, he seemed already more convinced about naming birds in his music, because he wrote the name of the blackbird in the score once. This happens in bar 20-27 of the Communion, where he titled the upper voice Chant de merle (Blackbird song; Picture 3). There are one other references to blackbirds in the Communion, but this one is not mentioned in the score. Within bar 14-20, there is dialogue between on the one hand, a blackbird that sings ornamented, joyful and quick whistles and, on the other hand, a cuckoo that calls from a distance. Within the score, those birds are marked as oiseaux (Picture 4). However, years after the release of the Messe de la Pentecôte, Messiaen explained during one of his organ masterclasses - attended by the American organist Jon Gillock - that this passage refers to a dialogue between a blackbird and a cuckoo.29 Notwithstanding the fact that he was not always certain about his 'musical' blackbirds, Messiaen was aware of some general characteristics of the real-life blackbird song that he took into account during the birdsong incorporation. Here, those blackbird characteristics are analyzed and compared to the music score.
Individual variations among blackbirds. A first characteristic is that each male blackbird - the female blackbirds never sing - develops a personal collections of song themes during its life.30 At the start of the spring, every blackbird starts with singing themes and motifs that he invented during previous spring times and tries to improve it through the addition of new song materials. Due to those large individual differences, Messiaen decided to make his 'musical' blackbirds individually different. In the Communion, the two blackbirds passages vary a lot in terms of speed, rhythms, musical sentences, development of motifs, ornamentions and moments of break. Moreover, the difference is indicated by the use of diverse stop prescriptions. The blackbird of bar 14-20 has to be played on a bourdon 8', while the chant de merle of bar 20-27 is represented by a flûte 4'.
Regular intervals. Despite the aforementioned individual differences, real-life blackbirds regularly sing a limited amount of intervals. According to Messiaen, their songs are 'based, if not on a hypermajor mode, at least on the use of the major third, perfect fourth, major sixth, and augmented fourth.'31 (Picture 5 en 6). For this reason, Messiaen incorporated those intervals in his music as well. Within the Chant de Merle of the Communion, three out of four aforementioned intervals appear (Picture 7). The major sixth interval can be found multiple times in the blackbird passages of bar 14-20 (Picture 8).
Song structure. Besides the consistent use of specific intervals, real-life blackbird songs often have a similar structure. For instance, blackbirds frequently make breaks in their songs. Within those fragmented passages, a similar structure can be recognized. This structure consists of a beginning at a relatively low frequency, followed by a sudden quick jump upwards that ends on an extremely high pitch (between 5000 and 8000 Hz) (Picture 9). Ornithologists call this a 'regular advertisement song'.32 It is unclear whether Messiaen was aware of this particular term, but he spoke in comparable terms about 'formulae always rising to a high pitch.'33 The blackbirds of the Communion also contain regular, short musical rests - particularly quavers and semiquavers - that fragment the song (Picture 7 and 8). However, a major difference with real-life blackbirds is that Messiaen's birds have lower frequencies. The highest note of Messiaen's blackbird is a D-natural''' in bar 21 with a frequency of 2349 Hz (Picture 10; top right). Comparably, real blackbirds can reach 5000 to 8000 Hz. Another structural characteristic that both Messiaen's birds and their real-life peers have in common, is the repetition of motifs during their songs. Within Messiaen's music, the repetition of motifs means that Messiaen used the exactly the same notes and rhythmical patterns. In other words, the pitch does not change. For instance, the blackbird of bar 14-20 of the Communion sings twice a rising hemidemisemiquaver motif, followed by a jump towards a B-natural''' (in bar 14 and 19; Picture 10; top left). Considering repeated motifs within the real-life blackbird songs, it can be concluded that the pitches are always different, even though a human ear cannot distinguish those different pitches. Moreover, real blackbirds never sing pitches of fixed musical tones like music instruments do. As can be seen in Picture 11, the pitches are always somewhat higher of lower than the fixed tones of the Western musical system (e.g. A-natural+; A-natural - ). Despite those differences, a human ear does hear the same 'tones' in this motif and consequently, a composer like Messiaen incorporated these motifs as similar forms in his music.
Emotional contrasts. A major characteristic of each blackbird song, according to Messiaen, is that is full of different emotional moods. On the one hand, the song can be both 'mocking, ironic and exuberantly joyful.'34 Within the Communion, this is reflected by fast rubato passages (Picture 7) that include fast, often staccato notes, polyrhythm - for instance 9 (pour 8) in bar 17, which means 'nine in the space of eight' - and a lot of 'before-the-beat' acciaccaturas. Comparable irregular rhythms and acciaccaturas can be found in real-life blackbird songs as well (Picture 12). A major difference is that those rhythms never stick to rhythms of human music. Apart from virtuoso elements, the blackbird can also sing in a 'calm, peaceful and solemn' way.35 Within the Communion, this is best represented by bar 15 and the second half of bar 17, in which the blackbird sings notes with a long duration with short breaks in between (Picture 13).
Conclusion. The blackbirds of the Communion have been composed with a lot of musical compromises. It was difficult for Messiaen to incorporated a unifying blackbird sound, because the blackbird repertoire is enormously varied and each blackbird song differs individually from the other. For this reason, Messiaen made each blackbird part in the Communion different from the other, both, structurally, harmonically and rhythmically. Despite the large individual differences, blackbird songs do have several standard characteristics that Messiaen recognized. Therefore, he focused on incorporating regular repetition of motifs, standard intervals and the change between calm and restless passages. Exact musical notes of real blackbird songs were impossible to hear due to the speed of singing. That is why he translated blackbird transcriptions to his own harmonic thinking. Thus, a complete accurate transcription of real blackbird songs is not possible, but Messiaen tried to be as accurate as possible.