Ornithophony in the soundscape of Anaikatty Hills, Coimbatore, Tamil Nadu, India

An attempt has been made to understand the extent of ornithophony (vocalization of birds) in the soundscape of Anaikatty Hills.  The study was limited to 13 hours of daylight from dawn to dusk (06.00–19.00 h) between January 2015 and October 2016.  Six replicates of 5-minute bird call recordings were collected from each hour window in 24 recording spots of the study area.  Each 5-minute recording was divided into 150 ‘2-sec’ observation units for the detailed analysis of the soundscape. A total of 78 recordings amounting to 390 minutes of acoustic data allowed a preliminary analysis of the ornithophony of the area.  A total of 62 bird species were heard vocalizing during the study period and contributed 8,629 units.  A total of 73.75% acoustic space was occupied by birds, among which the eight dominant species alone contributed to 63.65% of ornithophony.  The remaining 26% of acoustic space was occupied by other biophonies (12.60%), geophony (5.57%), indistinct sounds (7.66%), and anthropogenic noise (0.41%).  Passerines dominated the vocalizations with 7,269 (84.24%) and non-passerines with 1,360 (15.76%) units.  Birds vocalized in all 13 observation windows, with a peak in the first three hours of the day (06.00–09.00 h).  Vocalizations of non-passerines were prominent in the dusk hours (18.00–19.00 h).