Sound recording of bird vocalisations in forests. II. Longitudinal profiles in vocal activity

As early morning bird vocalisation is a major feature of many bird communities, longitudinal profiles of vocal activity data, collected using sound recorders, were compared for a range of habitat types in the Tumut area of south-eastern Australia. There was a significant, and roughly linear, decline in vocal activity across the morning after an initial early peak of activity. Vocal activity persisted longer at sites located within large areas of continuous eucalypt forest than in the strip- and patch-shaped eucalypt remnants surrounded by extensive stands of radiata pine or at sites dominated by stands of radiata pine. There was evidence that the pattern of persistence of vocal activity differed among the different bird groups.