Geographical variation in bird song at different scales and its potential utility in monitoring the effects of habitat fragmentation

Abstract

The cultural transmission of birdsongs has been proven to be of significant importance. Several studies have found male birds interacting with neighbouring birds in the adjacent territories for purposes such as territorial defense and mate attraction. During such interactions, they have been found to share songs with their neighbours, which may involve them singing song types that are similar to that of their neighbours. Several studies have found that song-sharing between neighbouring birds may help males maintain territory tenure and reproductive success. A number of studies have also found song sharing to correlate with the geographical distance between birds’ territories. Habitat fragmentation has been found to hamper this process of song-sharing between neighbouring birds. Thus we may use song sharing as an indicator of habitat fragmentation. I aimed at inquiring whether a correlation exists between song sharing and the geographical distances of the territories of the Ashy prinia (Prinia socialis) at IISER Pune, Maharashtra and that of the Pale-chinned flycatcher (Cyornis poliogenys) in Nongkhyllem Wildlife Sanctuary, Meghalaya, respectively. No significant correlation was found as a result of this study. Habitat fragmentation or barriers may also lead to geographical variations in birdsong. I aimed to study this as well in this thesis by examining geographical variations between the respective three Ashy prinia (Prinia socialis) subspecies and three Grey-breasted prinia (Prinia hodgsonii) subspecies that are both found extensively in India. Data was collected from online song databases which had the acoustic data of the various subspecies taken in accordance with their respective habitat distributions. Analysis revealed that there was no significant evidence of this in the Grey-breasted prinia (Prinia hodgsonii) subspecies but statistical analysis showed a significant result for the Ashy prinia (Prinia socialis) subspecies, although this is preliminary on account of the low sample size. Nevertheless, studying song sharing in birdsong can still serve as a useful tool for conservation purposes, pending further study.