Tolerance of Auditory Disturbance by an Avian Urban Adapter, the Noisy Miner

Authors


Hélène Lowry, School of Biological Sciences, Monash University, Clayton Campus, Victoria 3800, Australia.
E-mail: helene.lowry@monash.edu

Abstract

Urbanization creates challenges for wildlife, most notably through changes in resource availability and the frequent occurrence of sensory disturbance. Some native species, however, have been able to exploit and thrive in urban environments. Research, in this regard, has mostly focused on the ecological conditions that have allowed such species to prosper. In contrast, less attention has been devoted to evaluating how they cope with human proximity and disturbance. In a field experiment on a successful Australian ‘urban adapter’, the Noisy miner, Manorina melanocephala, we compared tolerance of a loud, startling sound stimulus by urban and rural individuals. We found group size differences between birds occupying urban and rural sites: more urban birds came into the testing area in response to the initial alarm-call playback compared with rural birds. Urban and rural birds also differed significantly in their behavioural response profile to the test sound stimulus. Nearly half (47.5%) of the rural, but only 22.5% of the urban birds took flight and of those that did, only 1 of 9 urban individuals retreated >5 m, compared with 13 of 19 rural birds. About one-third of urban, but only 5% of rural individuals responded to the sound stimulus with aggressive displays. The most frequent response to the stimulus, irrespective of habitat type, was to remain near the sound source and engage in visual surveillance. The high frequency of this response in both urban and rural individuals suggested that most noisy miners were quite ‘bold’, a temperament trait that is likely to be important in successful urban colonization by birds.

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