Hey mister Tambourine Dove, sing a song for me: simple but individually specific songs of Turtur tympanistria from Cameroon

摘要

Background: The broadcast song of the Tambourine Dove (Turtur tympanistria) is a repetitive coo series produced in a very stereotyped way. The song is similar to those of the other species within the Turtur genus and likely reflects the adaptation to long distance signalling in tropical habitats. There is no study assessing individual variation of the Tambourine Dove song or for the possibility of identity coding through song features. Methods: We obtained recordings of 578 songs from 41 males within a population inhabiting montane forest in Cameroon between 2008 and 2018. Additionally, we analysed also recordings from automatic recorders working for a longer time during the year. Songs were analysed to get basic information about within- and between-individual spectro-temporal variation. Potential of identity coding and discriminant analyses were used to investigate if and how these songs may convey information about male identity. Results: The song of the Tambourine Dove is a very simple series of short, unmodulated whistles with low frequency and a narrow bandwidth. Measurements of single song features indicated either none or a weak potential for identity coding. The overall variation in song frequency characteristics was very low. However, the number of notes forming a song (and consequently the duration) had a similar variability both within- and between individuals. When using multiple song measurements discrimination analysis revealed a high potential for identity coding although it seems that the temporal pattern of the beginning of a song carries the most information about sender identity. The production of initial notes within a song has very precise, individually specific timing allowing for up to 96.7% correct recognitions of songs. Comparison of recordings from the same points but separated in time by over a month indicates that song parameters are individually stable over longer period. Conclusions: Despite having highly stereotyped and simple songs, Tambourine Dove males produce individually specific signals which have a great potential for recognition by rivals or mates. All Turtur doves have similar yet unique songs that are different to the songs of other pigeon species. This genus seems to be a perfect model for studying the trade-off between coding for species identity and individual identity in a non-learning bird species. The described method of individual recognition allows for nonintrusive population monitoring.