Cryptic song? Taxonomy of the warbler Plain Prinia based on song analysis

Abstract: The warbler Prinia inornata (Plain Prinia) is a common songbird found across large parts of southern Asia, and it is currently divided into ten geographically distinct subspecies. It has been suggested by some ornithologists to possibly be a complex of cryptic species, i.e. several species so similar to each other that they have been taxonomically misclassified as being conspecific. This study used audio recordings to compare songs between individuals from different regions in order to see if there are distinct geographical differences, and if so, how these correspond to the current taxonomy. The comparison was made using two methods: A qualitative auditory analysis, and statistical models (NMDS and PCA) based on measurements from spectrograms.  The results show that two main types of song exist that are highly distinct from each other, each taking up roughly half of the geographical range. The two main types can be further divided into a few subtypes, potentially as many as seven in total. The geographical distribution of these subtypes matches that of some of the current subspecies, but the results do not support the current taxonomy as a whole. It is therefore likely that P. inornata comprises at least two species (corresponding to the two main types), possibly more.